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Leong SS, Korel F, King JH. Bacillus cereus: A review of "fried rice syndrome" causative agents. Microb Pathog 2023; 185:106418. [PMID: 37866551 DOI: 10.1016/j.micpath.2023.106418] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 10/19/2023] [Accepted: 10/19/2023] [Indexed: 10/24/2023]
Abstract
"Fried rice syndrome" originated from the first exposure to a fried rice dish contaminated with Bacillus cereus. This review compiles available data on the prevalence of B. cereus outbreak cases that occurred between 1984 and 2019. The outcome of B. cereus illness varies dramatically depending on the pathogenic strain encounter and the host's immune system. B. cereus causes a self-limiting, diarrheal illness caused by heat-resistant enterotoxin proteins, and an emetic illness caused by the deadly toxin named cereulide. The toxins together with their extrinsic factors are discussed. The possibility of more contamination of B. cereus in protein-rich food has also been shown. Therefore, the aim of this review is to summarize the available data, focusing mainly on B. cereus physiology as the causative agent for "fried rice syndrome." This review emphasizes the prevalence of B. cereus in starchy food contamination and outbreak cases reported, the virulence of both enterotoxins and emetic toxins produced, and the possibility of contaminated in protein-rich food. The impact of emetic or enterotoxin-producing B. cereus on public health cannot be neglected. Thus, it is essential to constantly monitor for B. cereus contamination during food handling and hygiene practices for food product preparation.
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Affiliation(s)
- Sui Sien Leong
- Department of Animal Sciences and Fishery, Faculty of Agricultural and Forestry Sciences, Universiti Putra Malaysia, Nyabau Road, Bintulu, 97008, Sarawak, Malaysia; Institute of Ecosystem Science Borneo, Universiti Putra Malaysia Bintulu Sarawak Campus, Nyabau Road, Bintulu, 97008, Sarawak, Malaysia.
| | - Figen Korel
- Food Engineering Department, Faculty of Engineering, Izmir Institute of Technology, Urla, 35430, İzmir, Turkey
| | - Jie Hung King
- Department of Crop Science, Faculty of Agricultural and Forestry Sciences, Universiti Putra Malaysia, Nyabau Road, Bintulu, 97008, Sarawak, Malaysia
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Yehuda A, Malach E, Vanunu Ofri S, Slamti L, Kuo SH, Lau JZ, Oh MW, Adeoye J, Shlezinger N, Lereclus D, Lau GW, Hayouka Z. The quorum-sensing peptidic inhibitor rescues host immune system eradication: A novel infectivity mechanism. Proc Natl Acad Sci U S A 2023; 120:e2301045120. [PMID: 37607229 PMCID: PMC10469338 DOI: 10.1073/pnas.2301045120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 06/23/2023] [Indexed: 08/24/2023] Open
Abstract
Subverting the host immune system is a major task for any given pathogen to assure its survival and proliferation. For the opportunistic human pathogen Bacillus cereus (Bc), immune evasion enables the establishment of potent infections. In various species of the Bc group, the pleiotropic regulator PlcR and its cognate cell-cell signaling peptide PapR7 regulate virulence gene expression in response to fluctuations in population density, i.e., a quorum-sensing (QS) system. However, how QS exerts its effects during infections and whether PlcR confers the immune evading ability remain unclear. Herein, we report how interception of the QS communication in Bc obliterates the ability to affect the host immune system. Here, we designed a peptide-based QS inhibitor that suppresses PlcR-dependent virulence factor expression and attenuates Bc infectivity in mouse models. We demonstrate that the QS peptidic inhibitor blocks host immune system-mediated eradication by reducing the expression of PlcR-regulated major toxins similarly to the profile that was observed for isogenic strains. Our findings provide evidence that Bc infectivity is regulated by QS circuit-mediated destruction of host immunity, thus reveal a interesting strategy to limit Bc virulence and enhance host defense. This peptidic quorum-quenching agent constitutes a readily accessible chemical tool for studying how other pathogen QS systems modulate host immunity and forms a basis for development of anti-infective therapeutics.
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Affiliation(s)
- Avishag Yehuda
- Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agricultural, Food & Environment, The Hebrew University of Jerusalem, Rehovot76100, Israel
| | - Einav Malach
- Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agricultural, Food & Environment, The Hebrew University of Jerusalem, Rehovot76100, Israel
| | - Shahar Vanunu Ofri
- Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agricultural, Food & Environment, The Hebrew University of Jerusalem, Rehovot76100, Israel
| | - Leyla Slamti
- Unité Micalis, Domaine de La Minière, Unité Mixte de Recherche 1319, Institut National de la Recherche Agronomique, 78280Guyancourt, France
| | - Shanny Hsuan Kuo
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL61802
| | - Jonathan Z. Lau
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL61802
| | - Myung Whan Oh
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL61802
| | - John Adeoye
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food & Environment, The Hebrew University of Jerusalem, Rehovot76100, Israel
| | - Neta Shlezinger
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agricultural, Food & Environment, The Hebrew University of Jerusalem, Rehovot76100, Israel
| | - Didier Lereclus
- Unité Micalis, Domaine de La Minière, Unité Mixte de Recherche 1319, Institut National de la Recherche Agronomique, 78280Guyancourt, France
| | - Gee W. Lau
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL61802
| | - Zvi Hayouka
- Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agricultural, Food & Environment, The Hebrew University of Jerusalem, Rehovot76100, Israel
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Sun S, Xu Z, Hu H, Zheng M, Zhang L, Xie W, Sun L, Liu P, Li T, Zhang L, Chen M, Zhu X, Liu M, Yang Y, Zhou J. The Bacillus cereus toxin alveolysin disrupts the intestinal epithelial barrier by inducing microtubule disorganization through CFAP100. Sci Signal 2023; 16:eade8111. [PMID: 37192300 DOI: 10.1126/scisignal.ade8111] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 04/18/2023] [Indexed: 05/18/2023]
Abstract
Bacillus cereus is a Gram-positive bacterium that mainly causes self-limiting emetic or diarrheal illness but can also cause skin infections and bacteremia. Symptoms of B. cereus ingestion depend on the production of various toxins that target the gastric and intestinal epithelia. From a screen of bacterial isolates from human stool samples that compromised intestinal barrier function in mice, we identified a strain of B. cereus that disrupted tight and adherens junctions in the intestinal epithelium. This activity was mediated by the pore-forming exotoxin alveolysin, which increased the production of the membrane-anchored protein CD59 and of cilia- and flagella-associated protein 100 (CFAP100) in intestinal epithelial cells. In vitro, CFAP100 interacted with microtubules and promoted microtubule polymerization. CFAP100 overexpression stabilized microtubules in intestinal epithelial cells, leading to disorganization of the microtubule network and perturbation of tight and adherens junctions. The disruption of cell junctions by alveolysin depended on the increase in CFAP100, which in turn depended on CD59 and the activation of PI3K-AKT signaling. These findings demonstrate that, in addition to forming membrane pores, B. cereus alveolysin can permeabilize the intestinal epithelium by disrupting epithelial cell junctions in a manner that is consistent with intestinal symptoms and may allow the bacteria to escape the intestine and cause systemic infections. Our results suggest the potential value of targeting alveolysin or CFAP100 to prevent B. cereus-associated intestinal diseases and systemic infections.
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Affiliation(s)
- Shuang Sun
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Zhaoyang Xu
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Haijie Hu
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Manxi Zheng
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Liang Zhang
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Wei Xie
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Lei Sun
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Peiwei Liu
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Tianliang Li
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Liangran Zhang
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Min Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Xueliang Zhu
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, China
| | - Min Liu
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Yunfan Yang
- Department of Cell Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Jun Zhou
- Center for Cell Structure and Function, Haihe Laboratory of Cell Ecosystem, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, Institute of Biomedical Sciences, College of Life Sciences, Shandong Normal University, Jinan 250014, China
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin 300071, China
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Yang S, Wang Y, Ren F, Li Z, Dong Q. Applying enzyme treatments in Bacillus cereus biofilm removal. Lebensm Wiss Technol 2023. [DOI: 10.1016/j.lwt.2023.114667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
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Grizanova EV, Krytsyna TI, Kalmykova GV, Sokolova E, Alikina T, Kabilov M, Coates CJ, Dubovskiy IM. Virulent and necrotrophic strategies of Bacillus thuringiensis in susceptible and resistant insects, Galleria mellonella. Microb Pathog 2023; 175:105958. [PMID: 36572197 DOI: 10.1016/j.micpath.2022.105958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 12/03/2022] [Accepted: 12/21/2022] [Indexed: 12/25/2022]
Abstract
Bacillus thuringiensis (Bt) is one of the most common entomopathogenic bacteria used as a biopesticide, and source of endotoxin genes for generating insect-resistant transgenic plants. The mechanisms underpinning an insect's susceptibility or resistance to B. thuringiensis are diverse. The bacterial lifecycle does not end with the death of a host, they continue to exploit the cadaver to reproduce and sporulate. Herein, we studied the progression of B. thuringiensis subsp. galleriae infection in two populations of wax moth larvae (Galleria mellonella) to gain further insight into the "arms race" between B. thuringiensis virulence and insect defences. Two doses of B. thuringiensis subsp. galleriae (spore and crystalline toxin mixtures) were administered orally to compare the responses of susceptible (S) and resistant (R) populations at ∼30% mortality each. To investigate B. thuringiensis-insect antibiosis, we used a combination of in vivo infection trials, bacterial microbiome analysis, and RNAi targeting the antibacterial peptide gloverin. Within 48 h post-inoculation, B. thuringiensis-resistant insects purged the midgut of bacteria, i.e., colony forming unit numbers fell below detectable levels. Second, B. thuringiensis rapidly modulated gene expression to initiate sporulation (linked to quorum sensing) when exposed to resistant insects in contrast to susceptible G. mellonella. We reinforce earlier findings that elevated levels of antimicrobial peptides, specifically gloverin, are found in the midgut of resistant insects, which is an evolutionary strategy to combat B. thuringiensis infection via its main portal of entry. A sub-population of highly virulent B. thuringiensis can survive the enhanced immune defences of resistant G. mellonella by disrupting the midgut microbiome and switching rapidly to a necrotrophic strategy, prior to sporulation in the cadaver.
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Affiliation(s)
- Ekaterina V Grizanova
- Department of Plant Protection, Novosibirsk State Agrarian University, 630039, Novosibirsk, Russia.
| | - Tatiana I Krytsyna
- Department of Plant Protection, Novosibirsk State Agrarian University, 630039, Novosibirsk, Russia.
| | - Galina V Kalmykova
- Faculty of Physical Engineering, Novosibirsk State Technical University, 630039, Novosibirsk, Russia.
| | - Elina Sokolova
- Department of Plant Protection, Novosibirsk State Agrarian University, 630039, Novosibirsk, Russia.
| | - Tatyana Alikina
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, 630039, Novosibirsk, Russia.
| | - Marsel Kabilov
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, 630039, Novosibirsk, Russia.
| | - Christopher J Coates
- Zoology, Ryan Institute, School of Natural Sciences, University of Galway, Galway, H91 TK33, Ireland; Department of Biosciences, Faculty of Science and Engineering, Swansea University, Swansea, SA2 8PP, Wales, UK.
| | - Ivan M Dubovskiy
- Department of Plant Protection, Novosibirsk State Agrarian University, 630039, Novosibirsk, Russia.
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Occurrence and characterization of toxigenic Bacillus cereus in dairy products with an inactivation trial using D-Tryptophan and ascorbic acid in the rice pudding. Lebensm Wiss Technol 2023. [DOI: 10.1016/j.lwt.2023.114485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Rajalingam N, Jung J, Seo SM, Jin HS, Kim BE, Jeong MI, Kim D, Ryu JG, Ryu KY, Oh KK. Prevalence, distribution, enterotoxin profiles, antimicrobial resistance, and genetic diversity of Bacillus cereus group isolates from lettuce farms in Korea. Front Microbiol 2022; 13:906040. [PMID: 36081801 PMCID: PMC9445581 DOI: 10.3389/fmicb.2022.906040] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 07/31/2022] [Indexed: 11/28/2022] Open
Abstract
Lettuce wraps are popular in Korean cuisine for their high nutritional value and versatility as healthy additions to multiple dishes. Microbial contamination of lettuce is a major concern, as lettuce is consumed fresh without cooking. Among foodborne pathogens, the spore-forming, facultative anaerobic bacterium, Bacillus cereus is one of the frequently detected pathogen in lettuce in Korea. In this study, we investigated the prevalence and distribution of Bacillus cereus strains in lettuce production farms and further evaluated the enterotoxin gene profiles, antibiotic susceptibility, multidrug resistance pattern, and genetic differences among the B. cereus group isolates. Of the 140 samples isolated from 10 lettuce production farms, 30 samples (21.42%) were positive for B. cereus in which 19 (31.6%) and 10 (23.25%) were from soil and lettuce, respectively. The enterotoxin patterns A (hblCDA, nheABC, entFM, and cytK genes) and B (hblCDA, nheABC, and entFM genes) accounted for 50% and 20% of all the isolates, whereas the emetic gene cesB was not detected in any of the B. cereus group isolates. Antibiotic susceptibility testing of the B. cereus group isolates revealed that all the strains were predominantly resistant to β-lactam antibiotics except imipenem and generally susceptible to most of the non β-lactam antibiotics, including gentamycin, streptomycin, chloramphenicol, and tetracycline. ERIC-PCR and MLST analysis revealed high genetic diversity among the 30 B. cereus group isolates, which belonged to 26 different sequence types (STs) and seven new STs. Moreover, isolates with identical STs exhibited similar patterns of antibiotic resistance and enterotoxin profiles. Results of this study indicate a high prevalence of B. cereus group isolates in lettuce production farms in the Republic of Korea.
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Affiliation(s)
- Nagendran Rajalingam
- Microbial Safety Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, South Korea
| | - Jieun Jung
- Functional Food and Nutrition Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, South Korea
| | - Seung-Mi Seo
- Microbial Safety Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, South Korea
| | - Hyun-Sook Jin
- Microbial Safety Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, South Korea
| | - Bo-Eun Kim
- Microbial Safety Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, South Korea
| | - Myeong-In Jeong
- Microbial Safety Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, South Korea
| | - Dawoon Kim
- Microbial Safety Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, South Korea
| | - Jae-Gee Ryu
- Planning and Coordination Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, South Korea
| | - Kyoung-Yul Ryu
- Microbial Safety Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, South Korea
| | - Kwang Kyo Oh
- Microbial Safety Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, South Korea
- *Correspondence: Kwang Kyo Oh,
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Chen J, Zhang J, Zhan L, Chen H, Zhang Z, Huang C, Yue M. Prevalence and antimicrobial-resistant characterization of Bacillus cereus isolated from ready-to-eat rice products in Eastern China. Front Microbiol 2022; 13:964823. [PMID: 35928146 PMCID: PMC9344136 DOI: 10.3389/fmicb.2022.964823] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 06/28/2022] [Indexed: 12/12/2022] Open
Abstract
Bacillus cereus is a major food-borne bacterial pathogen in the world, which can cause diarrhea and emetic syndrome. This study aimed to reveal the quantitative prevalence of B. cereus in ready-to-eat (RTE) rice products in Eastern China and to gain essential information on the characteristics of B. cereus isolates. A total of 91 out of the 1071 samples were positive for B. cereus. The contamination level of B. cereus in 0.5 % of RTE rice product samples outnumbered 103 CFU/g. The number of B. cereus attained 105−106 CFU/g in one sample. The distribution patterns of virulence genes in B. cereus isolates were identified. 84.6% of the B. cereus isolates had at least one enterotoxin or emetic toxin gene. The predominant pattern was XXV. 9.9% of isolates belonged to it and possessed one enterotoxin gene entFM. The occurrence rate of hblACD and nheABC was 36.3% and 47.3%, respectively. Antimicrobial susceptibility tests revealed a high resistance rate toward penicillin, and 23.1% of the isolates were multi-drug resistant. B. cereus isolates were genotyped by using ERIC-PCR. 89 genotypes were determined. The Hunter Gaston Discriminatory Index (HGDI) attained 0.9995. Relationships analysis revealed that Group A B. cereus isolates tended to carry hblA, hblC, hblD, nheA, nheB, and show resistance to penicillin/trimethoprim/sulfamethoxazole. This study was useful for updating the knowledge of the contamination status of B. cereus in RTE rice products in China.
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Affiliation(s)
- Jiancai Chen
- Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Junyan Zhang
- Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Li Zhan
- Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Honghu Chen
- Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Zhen Zhang
- Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Cheng Huang
- Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
- *Correspondence: Cheng Huang,
| | - Min Yue
- Hainan Institute, Zhejiang University, Hangzhou, China
- Institute of Preventive Veterinary Sciences and Department of Veterinary Medicine, Zhejiang University College of Animal Sciences, Hangzhou, China
- Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou, China
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, National Medical Center for Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
- Min Yue,
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Regulation of Enterotoxins Associated with Bacillus cereus Sensu Lato Toxicoinfection. Appl Environ Microbiol 2022; 88:e0040522. [PMID: 35730937 PMCID: PMC9275247 DOI: 10.1128/aem.00405-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Bacillus cereus sensu lato (s.l.) includes foodborne pathogens, as well as beneficial microorganisms, such as bioinsecticides. Some of the beneficial and commercially used B. cereus s.l. strains have been shown to carry enterotoxin genes, the products of which can cause toxicoinfection in humans. Furthermore, recent epidemiological reports indicated that some bioinsecticidal strains have been linked with foodborne illness outbreaks. This demonstrates the need for improved surveillance of B. cereus s.l., which includes characterization of isolates' virulence capacity. However, the prediction of virulence capacity of B. cereus s.l. strains is challenging. Genetic screening for enterotoxin gene presence has proven to be insufficient for accurate discrimination between virulent and avirulent strains, given that nearly all B. cereus s.l. strains carry at least one enterotoxin gene. Furthermore, complex regulatory networks governing the expression of enterotoxins, and potential synergistic interactions between enterotoxins and other virulence factors make the prediction of toxicoinfection based on isolates' genome sequences challenging. In this review, we summarize and synthesize the current understanding of the regulation of enterotoxins associated with the B. cereus s.l. toxicoinfection and identify gaps in the knowledge that need to be addressed to facilitate identification of genetic markers predictive of cytotoxicity and toxicoinfection.
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A Genomic Island of Vibrio cholerae Encodes a Three-Component Cytotoxin with Monomer and Protomer Forms Structurally Similar to Alpha-Pore-Forming Toxins. J Bacteriol 2022; 204:e0055521. [PMID: 35435721 DOI: 10.1128/jb.00555-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Alpha-pore-forming toxins (α-PFTs) are secreted by many species of bacteria, including Escherichia coli, Aeromonas hydrophila, and Bacillus thuringiensis, as part of their arsenal of virulence factors, and are often cytotoxic. In particular, for α-PFTs, the membrane-spanning channel they form is composed of hydrophobic α-helices. These toxins oligomerize at the surface of target cells and transition from a soluble to a protomer state in which they expose their hydrophobic regions and insert into the membrane to form a pore. The pores may be composed of homooligomers of one component or heterooligomers with two or three components, resulting in bi- or tripartite toxins. The multicomponent α-PFTs are often expressed from a single operon. Recently, motility-associated killing factor A (MakA), an α-PFT, was discovered in Vibrio cholerae. We report that makA is found on the V. cholerae GI-10 genomic island within an operon containing genes for two other potential α-PFTs, MakB and MakE. We determined the X-ray crystal structures for MakA, MakB, and MakE and demonstrated that all three are structurally related to the α-PFT family in the soluble state, and we modeled their protomer state based on the α-PFT AhlB from A. hydrophila. We found that MakA alone is cytotoxic at micromolar concentrations. However, combining MakA with MakB and MakE is cytotoxic at nanomolar concentrations, with specificity for J774 macrophage cells. Our data suggest that MakA, -B, and -E are α-PFTs that potentially act as a tripartite pore-forming toxin with specificity for phagocytic cells. IMPORTANCE The bacterium Vibrio cholerae causes gastrointestinal, wound, and skin infections. The motility-associated killing factor A (MakA) was recently shown to be cytotoxic against colon, prostate, and other cancer cells. However, at the outset of this study, the capacity of MakA to damage cells in combination with other Mak proteins encoded in the same operon had not been elucidated. We determined the structures of three Mak proteins and established that they are structurally related to the α-PFTs. Compared to MakA alone, the combination of all three toxins was more potent specifically in mouse macrophages. This study highlights the idea that the Mak toxins are selectively cytotoxic and thus may function as a tripartite toxin with cell type specificity.
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Seaweed-associated heterotrophic bacteria: are they future novel sources of antimicrobial agents against drug-resistant pathogens? Arch Microbiol 2022; 204:232. [PMID: 35355132 DOI: 10.1007/s00203-022-02835-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/06/2022] [Accepted: 03/09/2022] [Indexed: 11/02/2022]
Abstract
Emergence of multidrug-resistant microorganisms and requirements for novel antimicrobial compounds necessitate exploring newer habitats to develop potential bioactive leads. Culture-contingent analysis of heterotrophic bacterial flora from the seaweeds led to the isolation of bioactive strains possessing potential antibacterial properties against wide-ranging clinical pathogens viz., methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VREfs). Seven of the most active strains belonging to the phylum Firmicutes isolated from a brown seaweed (Phaeophyceae) Sargassum wightii exhibited spot-over-lawn assay guided inhibition zone of larger than 30 mm. Integrated phenotypic and genotypic studies have led to the characterization of the seaweed-associated bacteria particularly belonging to the phylum Firmicutes. The organic extracts of the studied bacteria exhibited promising antibacterial properties against MRSA and VREfs with minimum inhibitory concentration ranging between 6.25 and 12.50 μg/mL. Time-kill kinetic profiles of those bacteria displayed rapid bactericidal activity against both E. coli and MRSA, showing a ≥ 3log10 reduction in viable cell count than the initial. Among the studied bioactive Bacillus spp, B. tequilensis MTCC13043 and B. altiitudinis MTCC13046 were found to possess functional polyketide synthase (pks) gene (MW027664 and MW027660) that could be amplified. The outcome of amplified genes encrypting for polyketide synthase in conjunction with antibacterial activities unveiled the broad-spectrum antimicrobial activities of the marine heterotrophic Firmicutes, which could be further used against the emergent problem of antibiotic-resistant bacterial pathogens.
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12
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Jessberger N, Diedrich R, Janowski R, Niessing D, Märtlbauer E. Presence and function of Hbl B', the fourth protein component encoded by the hbl operon in Bacillus cereus. Virulence 2022; 13:483-501. [PMID: 35291913 PMCID: PMC8932913 DOI: 10.1080/21505594.2022.2046951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The genes hblC, hblD and hblA encode the components Hbl L2, L1 and B of the pore forming enterotoxin haemolysin BL of Bacillus cereus. Two variants of the operon existand the more common one additionally contains hblB downstream of hblCDA. Up to now, it was completely unclear whether the corresponding protein, Hbl B', is widely expressed among B. cereus strains and if it has a distinct function. In the present study, it was shown that the hblB gene is indeed expressed and the Hbl B' protein is secreted by nearly all analysed B. cereus strains. For the latter, a detection system was developed based on monoclonal antibody 11A5. Further, a distinct reduction of cytotoxic and haemolytic activity was observed when recombinant (r)Hbl B' was applied simultaneously with L2, L1 and B. This effect was due to direct interaction of rHbl B' with L1. D-6B. cereusAltogether, we present the first simple tool for the detection of Hbl B' in B. cereus culture supernatants. Moreover, an important regulatory function of Hbl B' in the mechanism of Hbl was determined, which is best described as an additional control of complex formation, balancing the amounts of Hbl B-L1 complexes and the corresponding free subunits.
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Affiliation(s)
- Nadja Jessberger
- Institute for Food Quality and Food Safety, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Richard Diedrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Oberschleißheim, Germany
| | - Robert Janowski
- Institute of Structural Biology, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany
| | - Dierk Niessing
- Institute of Structural Biology, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany.,Institute of Pharmaceutical Biotechnology, Ulm University, Ulm, Germany
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Oberschleißheim, Germany
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13
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Antibiotic-active heterotrophic Firmicutes sheltered in seaweeds: can they add new dimensions to future antimicrobial agents? Arch Microbiol 2022; 204:183. [PMID: 35179656 DOI: 10.1007/s00203-022-02784-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 01/22/2022] [Accepted: 01/28/2022] [Indexed: 11/02/2022]
Abstract
Appearance of drug-resistant microorganisms prompted researchers to unravel new environments for development of novel antimicrobial agents. Culture-supported analysis of heterotrophic bacteria associated with seaweeds yielded 152 strains, in that larger share of the isolates was embodied by Bacillus atrophaeus SHB2097 (54%), B. velezensis SHB2098 (24%), B. subtilis SHB2099 (12%), and B. amyloliquefaciens SHB20910 (10%). One of the most active strains characterized as B. atrophaeus SHB2097 (MW821482) with an inhibition zone more than 30 mm on spot-over-lawn experiment, was isolated from a seaweed Sargassum wightii, was selected for bioprospecting studies. Significant antibacterial potential was displayed by bacterial organic extract against vancomycin-resistant Enterococcus faecalis, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and Klebsiella pneumonia with minimum inhibitory concentration 6.25 µg/mL and comparable to the antibiotics ampicillin and chloramphenicol. The genes of type 1 pks (MZ222383, 700 bp) and hybrid nrps/pks (MZ222389, 1000-1400 bp) of B. atrophaeus MW821482 could be amplified. The bacterium displayed susceptibility to the commercially available antibiotic agents, and was negative for the pore-forming non-hemolytic hemolysin BL (hbl) and enterotoxin (nhe) genes, and therefore, was not pathogenic. The bacterium was found to possess genes (1000-1400 bp) involved in the biosynthesis of siderophore-class of compounds (MZ222387 and MZ222388) that showed 99% of similarity in BLAST search, and showed production of siderophore. Noteworthy antibacterial activities against clinically important pathogenic bacteria in conjunction with occurrence of genes coding for antimicrobial metabolites inferred that the marine heterotrophic bacterium B. atrophaeus SHB2097 could be used for the development of antibacterial agents against the emerging antibiotic resistance.
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14
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Nadeem A, Berg A, Pace H, Alam A, Toh E, Ådén J, Zlatkov N, Myint SL, Persson K, Gröbner G, Sjöstedt A, Bally M, Barandun J, Uhlin BE, Wai SN. Protein-lipid interaction at low pH induces oligomerization of the MakA cytotoxin from Vibrio cholerae. eLife 2022; 11:73439. [PMID: 35131030 PMCID: PMC8824476 DOI: 10.7554/elife.73439] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 01/19/2022] [Indexed: 12/29/2022] Open
Abstract
The α-pore-forming toxins (α-PFTs) from pathogenic bacteria damage host cell membranes by pore formation. We demonstrate a remarkable, hitherto unknown mechanism by an α-PFT protein from Vibrio cholerae. As part of the MakA/B/E tripartite toxin, MakA is involved in membrane pore formation similar to other α-PFTs. In contrast, MakA in isolation induces tube-like structures in acidic endosomal compartments of epithelial cells in vitro. The present study unravels the dynamics of tubular growth, which occurs in a pH-, lipid-, and concentration-dependent manner. Within acidified organelle lumens or when incubated with cells in acidic media, MakA forms oligomers and remodels membranes into high-curvature tubes leading to loss of membrane integrity. A 3.7 Å cryo-electron microscopy structure of MakA filaments reveals a unique protein-lipid superstructure. MakA forms a pinecone-like spiral with a central cavity and a thin annular lipid bilayer embedded between the MakA transmembrane helices in its active α-PFT conformation. Our study provides insights into a novel tubulation mechanism of an α-PFT protein and a new mode of action by a secreted bacterial toxin.
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Affiliation(s)
- Aftab Nadeem
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Alexandra Berg
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden.,Science for Life Laboratory (SciLifeLab), Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Hudson Pace
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden.,Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Athar Alam
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden
| | - Eric Toh
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Jörgen Ådén
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Chemistry, Umeå University, Umeå, Sweden
| | - Nikola Zlatkov
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Si Lhyam Myint
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Karina Persson
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Chemistry, Umeå University, Umeå, Sweden
| | - Gerhard Gröbner
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Chemistry, Umeå University, Umeå, Sweden
| | - Anders Sjöstedt
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden
| | - Marta Bally
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden.,Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Jonas Barandun
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Bernt Eric Uhlin
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Sun Nyunt Wai
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
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15
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Barale SS, Ghane SG, Sonawane KD. Purification and characterization of antibacterial surfactin isoforms produced by Bacillus velezensis SK. AMB Express 2022; 12:7. [PMID: 35084596 PMCID: PMC8795249 DOI: 10.1186/s13568-022-01348-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 01/16/2022] [Indexed: 11/10/2022] Open
Abstract
Bacillus velezensis SK having broad-spectrum antimicrobial activity has been isolated from soil. The efficient extraction of antimicrobial compounds produced in various mediums has been done using Diaion HP-20 resin. Further, characterization of an antimicrobial compound by TLC, FTIR, in-situ bioautography analysis revealed the presence of cyclic lipopeptides, which is then purified by the combination of silica gel, size exclusion, dual gradient, and RP-HPLC chromatography techniques. Growth kinetic studies showed that Bacillus velezensis SK produces a mixture of lipopeptides (1.33 gL-1). The lipopeptide exhibits good pH (2-10) and temperature stability up to 80 °C. LC-ESI-MS analysis of partially purified lipopeptide identified variant of surfactin, further analysis of purified chromatographic fractions revealed the occurrence of most abundant C15-surfactin homologues (m/z 1036.72 Da). The isolated surfactin exhibits good antimicrobial activity (1600 AU/ml) against drug-resistant food-born B. cereus and human pathogen Staphylococcus aureus. Hence, identified strain B. velezensis SK and its potent antibacterial surfactin lipopeptide could be used in various food and biomedical applications.
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16
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A tripartite cytolytic toxin formed by Vibrio cholerae proteins with flagellum-facilitated secretion. Proc Natl Acad Sci U S A 2021; 118:2111418118. [PMID: 34799450 PMCID: PMC8617504 DOI: 10.1073/pnas.2111418118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2021] [Indexed: 12/20/2022] Open
Abstract
Vibrio cholerae, responsible for outbreaks of cholera disease, is a highly motile organism by virtue of a single flagellum. We describe how the flagellum facilitates the secretion of three V. cholerae proteins encoded by a hitherto-unrecognized genomic island. The proteins MakA/B/E can form a tripartite toxin that lyses erythrocytes and is cytotoxic to cultured human cells. A structural basis for the cytolytic activity of the Mak proteins was obtained by X-ray crystallography. Flagellum-facilitated secretion ensuring spatially coordinated delivery of Mak proteins revealed a role for the V. cholerae flagellum considered of particular significance for the bacterial environmental persistence. Our findings will pave the way for the development of diagnostics and therapeutic strategies against pathogenic Vibrionaceae. The protein MakA was discovered as a motility-associated secreted toxin from Vibrio cholerae. Here, we show that MakA is part of a gene cluster encoding four additional proteins: MakB, MakC, MakD, and MakE. MakA, MakB, and MakE were readily detected in culture supernatants of wild-type V. cholerae, whereas secretion was very much reduced from a flagellum-deficient mutant. Crystal structures of MakA, MakB, and MakE revealed a structural relationship to a superfamily of bacterial pore-forming toxins. Expression of MakA/B/E in Escherichia coli resulted in toxicity toward Caenorhabditis elegans used as a predatory model organism. None of these Mak proteins alone or in pairwise combinations were cytolytic, but an equimolar mixture of MakA, MakB, and MakE acted as a tripartite cytolytic toxin in vitro, causing lysis of erythrocytes and cytotoxicity on cultured human colon carcinoma cells. Formation of oligomeric complexes on liposomes was observed by electron microscopy. Oligomer interaction with membranes was initiated by MakA membrane binding followed by MakB and MakE joining the assembly of a pore structure. A predicted membrane insertion domain of MakA was shown by site-directed mutagenesis to be essential for toxicity toward C. elegans. Bioinformatic analyses revealed that the makCDBAE gene cluster is present as a genomic island in the vast majority of sequenced genomes of V. cholerae and the fish pathogen Vibrio anguillarum. We suggest that the hitherto-unrecognized cytolytic MakA/B/E toxin can contribute to Vibrionaceae fitness and virulence potential in different host environments and organisms.
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17
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Categorizing sequences of concern by function to better assess mechanisms of microbial pathogenesis. Infect Immun 2021; 90:e0033421. [PMID: 34780277 PMCID: PMC9119117 DOI: 10.1128/iai.00334-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
To identify sequences with a role in microbial pathogenesis, we assessed the adequacy of their annotation by existing controlled vocabularies and sequence databases. Our goal was to regularize descriptions of microbial pathogenesis for improved integration with bioinformatic applications. Here, we review the challenges of annotating sequences for pathogenic activity. We relate the categorization of more than 2,750 sequences of pathogenic microbes through a controlled vocabulary called Functions of Sequences of Concern (FunSoCs). These allow for an ease of description by both humans and machines. We provide a subset of 220 fully annotated sequences in the supplemental material as examples. The use of this compact (∼30 terms), controlled vocabulary has potential benefits for research in microbial genomics, public health, biosecurity, biosurveillance, and the characterization of new and emerging pathogens.
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18
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Ramm F, Stech M, Zemella A, Frentzel H, Kubick S. The Pore-Forming Hemolysin BL Enterotoxin from Bacillus cereus: Subunit Interactions in Cell-Free Systems. Toxins (Basel) 2021; 13:toxins13110807. [PMID: 34822591 PMCID: PMC8623112 DOI: 10.3390/toxins13110807] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/05/2021] [Accepted: 11/12/2021] [Indexed: 11/16/2022] Open
Abstract
The tripartite enterotoxin Hemolysin BL (Hbl) has been widely characterized as a hemolytic and cytotoxic virulence factor involved in foodborne diarrheal illness caused by Bacillus cereus. Previous studies have described the formation of the Hbl complex and aimed to identify the toxin’s mode of action. In this study, we analyzed the assembly of Hbl out of its three individual subunits L1, L2 and B in a soluble as well as a putative membrane bound composition using a Chinese hamster ovary (CHO) cell-free system. Subunits were either coexpressed or synthesized individually in separate cell-free reactions and mixed together afterwards. Hemolytic activity of cell-free synthesized subunits was demonstrated on 5% sheep blood agar and identified both synthesis procedures, coexpression as well as individual synthesis of each subunit, as functional for the synthesis of an active Hbl complex. Hbl’s ability to perforate cell membranes was evaluated using a propidium iodide uptake assay. These data suggested that coexpressed Hbl subunits augmented cytotoxic activity with increasing concentrations. Further, a pre-pore-complex of L1-L2 showed cytotoxic effects suggesting the possibility of an interaction between the cell membrane and the pre-pore-complex. Overall, this study shows that cell-free protein synthesis is a fast and efficient way to study the assembly of multiple protein subunits in soluble as well as vesicular fractions.
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Affiliation(s)
- Franziska Ramm
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; (F.R.); (M.S.); (A.Z.)
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Marlitt Stech
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; (F.R.); (M.S.); (A.Z.)
| | - Anne Zemella
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; (F.R.); (M.S.); (A.Z.)
| | - Hendrik Frentzel
- Department of Biological Safety, German Federal Institute for Risk Assessment, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany;
| | - Stefan Kubick
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; (F.R.); (M.S.); (A.Z.)
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
- Faculty of Health Sciences, Joint Faculty of the Brandenburg University of Technology Cottbus–Senftenberg, Brandenburg Medical School Theodor Fontane and the University of Potsdam, 14476 Potsdam, Germany
- Correspondence: ; Tel.: +49-331-58-187-306; Fax: +49-331-58-187-199
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19
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Cheng LW, Rao S, Poudyal S, Wang PC, Chen SC. Genotype and virulence gene analyses of Bacillus cereus group clinical isolates from the Chinese softshell turtle (Pelodiscus sinensis) in Taiwan. JOURNAL OF FISH DISEASES 2021; 44:1515-1529. [PMID: 34125451 DOI: 10.1111/jfd.13473] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 06/12/2023]
Abstract
Chinese softshell turtles (Pelodiscus sinensis) (CST) are susceptible to infections by bacteria belonging to the Bacillus cereus group (Bcg). Bcg includes several closely related species, two of which, B. cereus and B. thuringiensis, are pathogens of aquatic animals or insects. In the present study, we collected 57 Bcg isolates obtained from diseased CST from 2016 to 2019 in Kaohsiung and Pingtung, the areas with the most CST farms in Taiwan. All isolates were divided into four genotypes with two restriction enzymes, SmaI and NotI, by pulsed-field gel electrophoresis and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR). Representative isolates from each genotype were subjected to phylogenetic tree analysis using 16S rDNA and pyruvate carboxylase genes as phylogenetic markers, and these CST isolates appeared in different clades. PCR was performed targeting six selected virulence genes, four of which were detected in CST isolates, including cytotoxin K (1/57), hblC of the haemolysin BL complex (46/57), nheA of the non-haemolytic enterotoxin complex (52/57) and enterotoxin FM (57/57), whereas cereulide synthetase and cereulide peptide synthase-like genes were not detected in any isolates.
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Affiliation(s)
- Li-Wu Cheng
- Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- College of Veterinary Medicine, Southern Taiwan Fish Diseases Research Centre, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Shreesha Rao
- Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Sayuj Poudyal
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Pei-Chi Wang
- Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- College of Veterinary Medicine, Southern Taiwan Fish Diseases Research Centre, National Pingtung University of Science and Technology, Pingtung, Taiwan
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Research Centre for Fish Vaccine and Diseases, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Shih-Chu Chen
- Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- College of Veterinary Medicine, Southern Taiwan Fish Diseases Research Centre, National Pingtung University of Science and Technology, Pingtung, Taiwan
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Research Centre for Fish Vaccine and Diseases, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Research Centre for Animal Biologics, National Pingtung University of Science and Technology, Pingtung, Taiwan
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20
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Hu H, Liu M, Sun S. Pore-Forming Toxins During Bacterial Infection: Molecular Mechanisms and Potential Therapeutic Targets. DRUG DESIGN DEVELOPMENT AND THERAPY 2021; 15:3773-3781. [PMID: 34522083 PMCID: PMC8434828 DOI: 10.2147/dddt.s322393] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 08/19/2021] [Indexed: 12/17/2022]
Abstract
Bacterial infections are predominantly treated with antibiotics, and resistance to antibiotics is becoming an increasing threat to our health. Pore-forming toxins (PFTs) are virulence factors secreted by many pathogenic bacterial strains, both in acute and chronic infections. They are special membrane-targeting proteins that exert toxic effects by forming pores in the cell membrane. Recent studies have elucidated the structure of PFTs and the detailed molecular mechanisms of their pathogenicity. Here, we discuss recent findings that highlight the regulatory mechanisms and important roles of two types of PFTs, α-PFTs and β-PFTs, in mediating the virulence of bacteria, and the therapeutic potential of targeting PFTs for antibacterial treatment. Therapeutic strategies based on PFTs are highly specific and may alleviate the issue of increasing resistance to antibiotics.
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Affiliation(s)
- Haijie Hu
- Institute of Biomedical Sciences, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, 250014, People's Republic of China
| | - Min Liu
- Institute of Biomedical Sciences, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, 250014, People's Republic of China
| | - Shuang Sun
- Institute of Biomedical Sciences, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, 250014, People's Republic of China
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21
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Carroll LM, Cheng RA, Wiedmann M, Kovac J. Keeping up with the Bacillus cereus group: taxonomy through the genomics era and beyond. Crit Rev Food Sci Nutr 2021; 62:7677-7702. [PMID: 33939559 DOI: 10.1080/10408398.2021.1916735] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The Bacillus cereus group, also known as B. cereus sensu lato (s.l.), is a species complex that contains numerous closely related lineages, which vary in their ability to cause illness in humans and animals. The classification of B. cereus s.l. isolates into species-level taxonomic units is thus essential for informing public health and food safety efforts. However, taxonomic classification of these organisms is challenging. Numerous-often conflicting-taxonomic changes to the group have been proposed over the past two decades, making it difficult to remain up to date. In this review, we discuss the major nomenclatural changes that have accumulated in the B. cereus s.l. taxonomic space prior to 2020, particularly in the genomic sequencing era, and outline the resulting problems. We discuss several contemporary taxonomic frameworks as applied to B. cereus s.l., including (i) phenotypic, (ii) genomic, and (iii) hybrid nomenclatural frameworks, and we discuss the advantages and disadvantages of each. We offer suggestions as to how readers can avoid B. cereus s.l. taxonomic ambiguities, regardless of the nomenclatural framework(s) they choose to employ. Finally, we discuss future directions and open problems in the B. cereus s.l. taxonomic realm, including those that cannot be solved by genomic approaches alone.
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Affiliation(s)
- Laura M Carroll
- Structural and Computational Biology Unit, EMBL, Heidelberg, Germany
| | - Rachel A Cheng
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Jasna Kovac
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, USA
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22
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Worthy HL, Williamson LJ, Auhim HS, Leppla SH, Sastalla I, Jones DD, Rizkallah PJ, Berry C. The Crystal Structure of Bacillus cereus HblL 1. Toxins (Basel) 2021; 13:253. [PMID: 33807365 PMCID: PMC8065917 DOI: 10.3390/toxins13040253] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/26/2021] [Accepted: 03/29/2021] [Indexed: 02/07/2023] Open
Abstract
The Hbl toxin is a three-component haemolytic complex produced by Bacillus cereus sensu lato strains and implicated as a cause of diarrhoea in B. cereus food poisoning. While the structure of the HblB component of this toxin is known, the structures of the other components are unresolved. Here, we describe the expression of the recombinant HblL1 component and the elucidation of its structure to 1.36 Å. Like HblB, it is a member of the alpha-helical pore-forming toxin family. In comparison to other members of this group, it has an extended hydrophobic beta tongue region that may be involved in pore formation. Molecular docking was used to predict possible interactions between HblL1 and HblB, and suggests a head to tail dimer might form, burying the HblL1 beta tongue region.
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Affiliation(s)
- Harley L. Worthy
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AX, UK; (H.L.W.); (L.J.W.); (H.S.A.); (D.D.J.)
- The Henry Wellcome Building for Biocatalysis, Exeter University, Stocker Road, Exeter EX4 4QD, UK
| | - Lainey J. Williamson
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AX, UK; (H.L.W.); (L.J.W.); (H.S.A.); (D.D.J.)
| | - Husam Sabah Auhim
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AX, UK; (H.L.W.); (L.J.W.); (H.S.A.); (D.D.J.)
- Department of Biology, College of Science, University of Baghdad, Baghdad, Iraq
| | - Stephen H. Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA; (S.H.L.); (I.S.)
| | - Inka Sastalla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA; (S.H.L.); (I.S.)
- Scientific Review Program, Division of Extramural Activities, NIAID, NIH, Rockville, MD 20892, USA
| | - D. Dafydd Jones
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AX, UK; (H.L.W.); (L.J.W.); (H.S.A.); (D.D.J.)
| | | | - Colin Berry
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AX, UK; (H.L.W.); (L.J.W.); (H.S.A.); (D.D.J.)
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23
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Banerji R, Karkee A, Kanojiya P, Saroj SD. Pore-forming toxins of foodborne pathogens. Compr Rev Food Sci Food Saf 2021; 20:2265-2285. [PMID: 33773026 DOI: 10.1111/1541-4337.12737] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 02/01/2021] [Accepted: 02/08/2021] [Indexed: 01/04/2023]
Abstract
Pore-forming toxins (PFTs) are water-soluble molecules that have been identified as the most crucial virulence factors during bacterial pathogenesis. PFTs disrupt the host cell membrane to internalize or to deliver other bacterial or virulence factors for establishing infections. Disruption of the host cell membrane by PFTs can lead to uncontrollable exchanges between the extracellular and the intracellular matrix, thereby disturbing the cellular homeostasis. Recent studies have provided insights into the molecular mechanism of PFTs during pathogenesis. Evidence also suggests the activation of several signal transduction pathways in the host cell on recognition of PFTs. Additionally, numerous distinctive host defense mechanisms as well as membrane repair mechanisms have been reported; however, studies reveal that PFTs aid in host immune evasion of the bacteria through numerous pathways. PFTs have been primarily associated with foodborne pathogens. Infection and death from diseases by consuming contaminated food are a constant threat to public health worldwide, affecting socioeconomic development. Moreover, the emergence of new foodborne pathogens has led to the rise of bacterial antimicrobial resistance affecting the population. Hence, this review focuses on the role of PFTs secreted by foodborne pathogens. The review highlights the molecular mechanism of foodborne bacterial PFTs, assisting bacterial survival from the host immune responses and understanding the downstream mechanism in the activation of various signaling pathways in the host upon PFT recognition. PFT research is a remarkable and an important field for exploring novel and broad applications of antimicrobial compounds as therapeutics.
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Affiliation(s)
- Rajashri Banerji
- Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Pune, India
| | - Astha Karkee
- Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Pune, India
| | - Poonam Kanojiya
- Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Pune, India
| | - Sunil D Saroj
- Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Pune, India
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24
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Churchill-Angus AM, Schofield THB, Marlow TR, Sedelnikova SE, Wilson JS, Rafferty JB, Baker PJ. Characterisation of a tripartite α-pore forming toxin from Serratia marcescens. Sci Rep 2021; 11:6447. [PMID: 33742033 PMCID: PMC7979752 DOI: 10.1038/s41598-021-85726-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 03/03/2021] [Indexed: 01/31/2023] Open
Abstract
Tripartite members of the ClyA family of α-PFTs have recently been identified in a number of pathogenic Gram-negative bacteria, including the human pathogen Serratia marcescens. Structures of a Gram-negative A component and a tripartite α-PFT complete pore are unknown and a mechanism for pore formation is still uncertain. Here we characterise the tripartite SmhABC toxin from S. marcescens and propose a mechanism of pore assembly. We present the structure of soluble SmhA, as well as the soluble and pore forms of SmhB. We show that the β-tongue soluble structure is well conserved in the family and propose two conserved latches between the head and tail domains that are broken on the soluble to pore conformational change. Using the structures of individual components, sequence analysis and docking predictions we illustrate how the A, B and C protomers would assemble on the membrane to produce a complete tripartite α-PFT pore.
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Affiliation(s)
- Alicia M Churchill-Angus
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, South Yorkshire, UK
| | - Thomas H B Schofield
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, South Yorkshire, UK
- Current address: Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Thomas R Marlow
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, South Yorkshire, UK
| | - Svetlana E Sedelnikova
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, South Yorkshire, UK
| | - Jason S Wilson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, South Yorkshire, UK
| | - John B Rafferty
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, South Yorkshire, UK
| | - Patrick J Baker
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, South Yorkshire, UK.
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25
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Luo JC, Long H, Zhang J, Zhao Y, Sun L. Characterization of a Deep Sea Bacillus toyonensis Isolate: Genomic and Pathogenic Features. Front Cell Infect Microbiol 2021; 11:629116. [PMID: 33777842 PMCID: PMC7988205 DOI: 10.3389/fcimb.2021.629116] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 02/01/2021] [Indexed: 01/09/2023] Open
Abstract
Bacillus toyonensis is a group of Gram-positive bacteria belonging to the Bacillus cereus group and used in some cases as probiotics or biocontrol agents. To our knowledge, B. toyonensis from the deep sea (depth >1,000 m) has not been documented. Here, we report the isolation and characterization of a B. toyonensis strain, P18, from a deep sea hydrothermal field. P18 is aerobic, motile, and able to grow at low temperatures (4°C) and high concentrations of NaCl (8%). P18 possesses a circular chromosome of 5,250,895 bp and a plasmid of 536,892 bp, which encode 5,380 and 523 genes, respectively. Of these genes, 2,229 encode hypothetical proteins that could not be annotated based on the COG database. Comparative genomic analysis showed that P18 is most closely related to the type strain of B. toyonensis, BCT-7112T. Compared to BCT-7112T, P18 contains 1,401 unique genes, 441 of which were classified into 20 COG functional categories, and the remaining 960 genes could not be annotated. A total of 319 putative virulence genes were identified in P18, including toxin-related genes, and 24 of these genes are absent in BCT-7112T. P18 exerted strong cytopathic effects on fish and mammalian cells that led to rapid cell death. When inoculated via injection into fish and mice, P18 rapidly disseminated in host tissues and induced acute infection and mortality. Histopathology revealed varying degrees of tissue lesions in the infected animals. Furthermore, P18 could survive in fish and mouse sera and possessed hemolytic activity. Taken together, these results provide the first evidence that virulent B. toyonensis exists in deep sea environments.
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Affiliation(s)
- Jing-Chang Luo
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China.,College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Hao Long
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, China
| | - Jian Zhang
- School of Ocean, Yan Tai University, Yantai, China
| | - Yan Zhao
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Li Sun
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China.,College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
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26
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Asadpoor M, Ithakisiou GN, Henricks PAJ, Pieters R, Folkerts G, Braber S. Non-Digestible Oligosaccharides and Short Chain Fatty Acids as Therapeutic Targets against Enterotoxin-Producing Bacteria and Their Toxins. Toxins (Basel) 2021; 13:175. [PMID: 33668708 PMCID: PMC7996226 DOI: 10.3390/toxins13030175] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/08/2021] [Accepted: 02/17/2021] [Indexed: 02/07/2023] Open
Abstract
Enterotoxin-producing bacteria (EPB) have developed multiple mechanisms to disrupt gut homeostasis, and provoke various pathologies. A major part of bacterial cytotoxicity is attributed to the secretion of virulence factors, including enterotoxins. Depending on their structure and mode of action, enterotoxins intrude the intestinal epithelium causing long-term consequences such as hemorrhagic colitis. Multiple non-digestible oligosaccharides (NDOs), and short chain fatty acids (SCFA), as their metabolites produced by the gut microbiota, interact with enteropathogens and their toxins, which may result in the inhibition of the bacterial pathogenicity. NDOs characterized by diverse structural characteristics, block the pathogenicity of EPB either directly, by inhibiting bacterial adherence and growth, or biofilm formation or indirectly, by promoting gut microbiota. Apart from these abilities, NDOs and SCFA can interact with enterotoxins and reduce their cytotoxicity. These anti-virulent effects mostly rely on their ability to mimic the structure of toxin receptors and thus inhibiting toxin adherence to host cells. This review focuses on the strategies of EPB and related enterotoxins to impair host cell immunity, discusses the anti-pathogenic properties of NDOs and SCFA on EPB functions and provides insight into the potential use of NDOs and SCFA as effective agents to fight against enterotoxins.
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Affiliation(s)
- Mostafa Asadpoor
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands; (M.A.); (G.-N.I.); (P.A.J.H.); (G.F.)
| | - Georgia-Nefeli Ithakisiou
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands; (M.A.); (G.-N.I.); (P.A.J.H.); (G.F.)
| | - Paul A. J. Henricks
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands; (M.A.); (G.-N.I.); (P.A.J.H.); (G.F.)
| | - Roland Pieters
- Division of Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands;
| | - Gert Folkerts
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands; (M.A.); (G.-N.I.); (P.A.J.H.); (G.F.)
| | - Saskia Braber
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands; (M.A.); (G.-N.I.); (P.A.J.H.); (G.F.)
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27
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The Food Poisoning Toxins of Bacillus cereus. Toxins (Basel) 2021; 13:toxins13020098. [PMID: 33525722 PMCID: PMC7911051 DOI: 10.3390/toxins13020098] [Citation(s) in RCA: 99] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/14/2021] [Accepted: 01/25/2021] [Indexed: 12/13/2022] Open
Abstract
Bacillus cereus is a ubiquitous soil bacterium responsible for two types of food-associated gastrointestinal diseases. While the emetic type, a food intoxication, manifests in nausea and vomiting, food infections with enteropathogenic strains cause diarrhea and abdominal pain. Causative toxins are the cyclic dodecadepsipeptide cereulide, and the proteinaceous enterotoxins hemolysin BL (Hbl), nonhemolytic enterotoxin (Nhe) and cytotoxin K (CytK), respectively. This review covers the current knowledge on distribution and genetic organization of the toxin genes, as well as mechanisms of enterotoxin gene regulation and toxin secretion. In this context, the exceptionally high variability of toxin production between single strains is highlighted. In addition, the mode of action of the pore-forming enterotoxins and their effect on target cells is described in detail. The main focus of this review are the two tripartite enterotoxin complexes Hbl and Nhe, but the latest findings on cereulide and CytK are also presented, as well as methods for toxin detection, and the contribution of further putative virulence factors to the diarrheal disease.
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28
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Churchill-Angus AM, Sedelnikova SE, Schofield THB, Baker PJ. The A component (SmhA) of a tripartite pore-forming toxin from Serratia marcescens: expression, purification and crystallographic analysis. Acta Crystallogr F Struct Biol Commun 2020; 76:577-582. [PMID: 33263568 PMCID: PMC7716259 DOI: 10.1107/s2053230x20013862] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/17/2020] [Indexed: 01/17/2023] Open
Abstract
Tripartite α-pore-forming toxins are constructed of three proteins (A, B and C) and are found in many bacterial pathogens. While structures of the B and C components from Gram-negative bacteria have been described, the structure of the A component of a Gram-negative α-pore-forming toxin has so far proved elusive. SmhA, the A component from the opportunistic human pathogen Serratia marcescens, has been cloned, overexpressed and purified. Crystals were grown of selenomethionine-derivatized protein and anomalous data were collected. Phases were calculated and an initial electron-density map was produced.
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Affiliation(s)
- Alicia M. Churchill-Angus
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom
| | - Svetlana E. Sedelnikova
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom
| | - Thomas H. B. Schofield
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Patrick J. Baker
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom
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29
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Jessberger N, Dietrich R, Granum PE, Märtlbauer E. The Bacillus cereus Food Infection as Multifactorial Process. Toxins (Basel) 2020; 12:E701. [PMID: 33167492 PMCID: PMC7694497 DOI: 10.3390/toxins12110701] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 02/06/2023] Open
Abstract
The ubiquitous soil bacterium Bacillus cereus presents major challenges to food safety. It is responsible for two types of food poisoning, the emetic form due to food intoxication and the diarrheal form emerging from food infections with enteropathogenic strains, also known as toxico-infections, which are the subject of this review. The diarrheal type of food poisoning emerges after production of enterotoxins by viable bacteria in the human intestine. Basically, the manifestation of the disease is, however, the result of a multifactorial process, including B. cereus prevalence and survival in different foods, survival of the stomach passage, spore germination, motility, adhesion, and finally enterotoxin production in the intestine. Moreover, all of these processes are influenced by the consumed foodstuffs as well as the intestinal microbiota which have, therefore, to be considered for a reliable prediction of the hazardous potential of contaminated foods. Current knowledge regarding these single aspects is summarized in this review aiming for risk-oriented diagnostics for enteropathogenic B. cereus.
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Affiliation(s)
- Nadja Jessberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (R.D.); (E.M.)
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (R.D.); (E.M.)
| | - Per Einar Granum
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, P.O. Box 5003 NMBU, 1432 Ås, Norway;
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (R.D.); (E.M.)
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30
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Characteristics of the Protein Complexes and Pores Formed by Bacillus cereus Hemolysin BL. Toxins (Basel) 2020; 12:toxins12110672. [PMID: 33114414 PMCID: PMC7694065 DOI: 10.3390/toxins12110672] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/13/2020] [Accepted: 10/21/2020] [Indexed: 11/25/2022] Open
Abstract
Bacillus cereus Hemolysin BL is a tripartite toxin responsible for a diarrheal type of food poisoning. Open questions remain regarding its mode of action, including the extent to which complex formation prior to cell binding contributes to pore-forming activity, how these complexes are composed, and the properties of the pores formed in the target cell membrane. Distinct complexes of up to 600 kDa were found on native gels, whose structure and size were primarily defined by Hbl B. Hbl L1 and L2 were also identified in these complexes using Western blotting and an LC-MS approach. LC-MS also revealed that many other proteins secreted by B. cereus exist in complexes. Further, a decrease of toxic activity at temperatures ≥60 °C was shown, which was unexpectedly restored at higher temperatures. This could be attributed to a release of Hbl B monomers from tight complexation, resulting in enhanced cell binding. In contrast, Hbl L1 was rather susceptible to heat, while heat treatment of Hbl L2 seemed not to be crucial. Furthermore, Hbl-induced pores had a rather small single-channel conductance of around 200 pS and a probable channel diameter of at least 1 nm on planar lipid bilayers. These were highly instable and had a limited lifetime, and were also slightly cation-selective. Altogether, this study provides astonishing new insights into the complex mechanism of Hbl pore formation, as well as the properties of the pores.
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31
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Bacillus cereus: Epidemiology, Virulence Factors, and Host-Pathogen Interactions. Trends Microbiol 2020; 29:458-471. [PMID: 33004259 DOI: 10.1016/j.tim.2020.09.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 09/03/2020] [Accepted: 09/04/2020] [Indexed: 12/30/2022]
Abstract
The toxin-producing bacterium Bacillus cereus is an important and neglected human pathogen and a common cause of food poisoning. Several toxins have been implicated in disease, including the pore-forming toxins hemolysin BL (HBL) and nonhemolytic enterotoxin (NHE). Recent work revealed that HBL binds to the mammalian surface receptors LITAF and CDIP1 and that both HBL and NHE induce potassium efflux and activate the NLRP3 inflammasome, leading to pyroptosis. These mammalian receptors, in part, contribute to inflammation and pathology. Other putative virulence factors of B. cereus include cytotoxin K, cereulide, metalloproteases, sphingomyelinase, and phospholipases. In this review, we highlight the latest progress in our understanding of B. cereus biology, epidemiology, and pathogenesis, and discuss potential new directions for research in this field.
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32
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Unique inducible filamentous motility identified in pathogenic Bacillus cereus group species. ISME JOURNAL 2020; 14:2997-3010. [PMID: 32770116 PMCID: PMC7784679 DOI: 10.1038/s41396-020-0728-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 07/11/2020] [Accepted: 07/23/2020] [Indexed: 01/03/2023]
Abstract
Active migration across semi-solid surfaces is important for bacterial success by facilitating colonization of unoccupied niches and is often associated with altered virulence and antibiotic resistance profiles. We isolated an atmospheric contaminant, subsequently identified as a new strain of Bacillus mobilis, which showed a unique, robust, rapid, and inducible filamentous surface motility. This flagella-independent migration was characterized by formation of elongated cells at the expanding edge and was induced when cells were inoculated onto lawns of metabolically inactive Campylobacter jejuni cells, autoclaved bacterial biomass, adsorbed milk, and adsorbed blood atop hard agar plates. Phosphatidylcholine (PC), bacterial membrane components, and sterile human fecal extracts were also sufficient to induce filamentous expansion. Screening of eight other Bacillus spp. showed that filamentous motility was conserved amongst B. cereus group species to varying degrees. RNA-Seq of elongated expanding cells collected from adsorbed milk and PC lawns versus control rod-shaped cells revealed dysregulation of genes involved in metabolism and membrane transport, sporulation, quorum sensing, antibiotic synthesis, and virulence (e.g., hblA/B/C/D and plcR). These findings characterize the robustness and ecological significance of filamentous surface motility in B. cereus group species and lay the foundation for understanding the biological role it may play during environment and host colonization.
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33
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Elworth RAL, Diaz C, Yang J, de Figueiredo P, Ternus K, Treangen T. Synthetic DNA and biosecurity: Nuances of predicting pathogenicity and the impetus for novel computational approaches for screening oligonucleotides. PLoS Pathog 2020; 16:e1008649. [PMID: 32760120 PMCID: PMC7410204 DOI: 10.1371/journal.ppat.1008649] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- R. A. Leo Elworth
- Department of Computer Science, Rice University, Houston, Texas, United States of America
| | - Christian Diaz
- Department of Computer Science, Rice University, Houston, Texas, United States of America
| | - Jing Yang
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
| | - Paul de Figueiredo
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
- Norman Borlaug Center, Texas A&M University, College Station, Texas, United States of America
| | - Krista Ternus
- Signature Science, LLC, Austin, Texas, United States of America
| | - Todd Treangen
- Department of Computer Science, Rice University, Houston, Texas, United States of America
- * E-mail:
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34
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Osama R, Ahmed M, Abdulmawjood A, Al-Ashmawy M. Prevalence and Antimicrobial Resistance of Bacillus cereus in Milk and Dairy Products. ACTA ACUST UNITED AC 2020. [DOI: 10.35943/mvmj.2020.2.202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Objective: To investigate the prevalence of Bacillus cereus in milk and dairy products along with detection of its antibiotic sensitivity.
Design: Descriptive study.
Samples: One hundred and fifty samples of market milk, ultra high temperature milk packs (UHT), condensed milk, Milk powder, Damietta cheese, Kariesh cheese and Ras cheese.
Procedures: Samples were examined for isolation and identification of Bacillus spp. via direct and indirect isolation, molecular examination and antimicrobial resistance. Further molecular examination was carried out in 46 isolates to detect hblA, hblC, hblD, nheA, nheB and nheC genes
Results: The prevalence of B. cereus by direct isolation was 52%, 13.3 %, 10%, 8%,44%, 0 % and 16% in market milk, ultra high temperature milk packs (UHT) , condensed milk , Milk powder, Damietta cheese, Kariesh cheese and Ras cheese, respectively, whereas its prevalence by indirect isolation was 64%, 20%, 20%, 48%, 52%, 40% and 36% in market milk, ultra high temperature milk packs (UHT) , condensed milk , Milk powder, Damietta cheese, Kariesh cheese and Ras cheese, respectively. B. cereus isolates were 100% resistant to colistin (CT), ampicillin (AM) and amoxicillin (AML). However, 83.01% were resistant to ampicillin-sulbactum (SAM), 67.9% resistant to streptomycin (S), 45.2% resistant to spiramycin (SP), 35.8% resistant to lincomysin (MY), 22.6% resistant to tetracyclin (TE), and 5.6% resistant to erythromycin (E). A prevalence of 58.6% for hblA, hblC and hblD was recorded, while a prevalence of 86.9%, 93.4% and 89.1% for nheA, nheB and nheC was recorded.
Conclusion and clinical relevance: This study provides data on prevalence, contamination level and antibiotic sensitivity of B. cereus in milk and its products, suggesting a potential risk to health and the dairy industry.
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Affiliation(s)
- Rowayda Osama
- Department of Food Hygiene and Control, Faculty of Veterinary Medicine, Mansoura University, Mansoura 35516, Egypt
| | - Marwa Ahmed
- Department of Hygiene and Zoonoses, Faculty of Veterinary Medicine, Mansoura University
| | - Amir Abdulmawjood
- Institute of Food Quality and Food Safety, Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, D-30559 Hannover, Germany
| | - Maha Al-Ashmawy
- Department of Food Hygiene and Control, Faculty of Veterinary Medicine, Mansoura University, Mansoura 35516, Egypt
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35
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Liu J, Zuo Z, Sastalla I, Liu C, Jang JY, Sekine Y, Li Y, Pirooznia M, Leppla SH, Finkel T, Liu S. Sequential CRISPR-Based Screens Identify LITAF and CDIP1 as the Bacillus cereus Hemolysin BL Toxin Host Receptors. Cell Host Microbe 2020; 28:402-410.e5. [PMID: 32544461 DOI: 10.1016/j.chom.2020.05.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/16/2020] [Accepted: 05/15/2020] [Indexed: 12/18/2022]
Abstract
Bacteria and their toxins are associated with significant human morbidity and mortality. While a few bacterial toxins are well characterized, the mechanism of action for most toxins has not been elucidated, thereby limiting therapeutic advances. One such example is the highly potent pore-forming toxin, hemolysin BL (HBL), produced by the gram-positive pathogen Bacillus cereus. However, how HBL exerts its effects and whether it requires any host factors is unknown. Here, we describe an unbiased genome-wide CRISPR-Cas9 knockout screen that identified LPS-induced TNF-α factor (LITAF) as the HBL receptor. Using LITAF-deficient cells, a second, subsequent whole-genome CRISPR-Cas9 screen identified the LITAF-like protein CDIP1 as a second, alternative receptor. We generated LITAF-deficient mice, which exhibit marked resistance to lethal HBL challenges. This work outlines and validates an approach to use iterative genome-wide CRISPR-Cas9 screens to identify the complement of host factors exploited by bacterial toxins to exert their myriad biological effects.
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Affiliation(s)
- Jie Liu
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA; Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Zehua Zuo
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA
| | - Inka Sastalla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chengyu Liu
- Transgenic Core Facility, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ji Yong Jang
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA
| | - Yusuke Sekine
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA
| | - Yuesheng Li
- DNA Sequencing and Genomics Core Facility, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mehdi Pirooznia
- Bioinformatics and Computational Biology Core Facility, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Toren Finkel
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA; Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Shihui Liu
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA; Division of Infectious Diseases, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA.
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36
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Fox D, Mathur A, Xue Y, Liu Y, Tan WH, Feng S, Pandey A, Ngo C, Hayward JA, Atmosukarto II, Price JD, Johnson MD, Jessberger N, Robertson AAB, Burgio G, Tscharke DC, Fox EM, Leyton DL, Kaakoush NO, Märtlbauer E, Leppla SH, Man SM. Bacillus cereus non-haemolytic enterotoxin activates the NLRP3 inflammasome. Nat Commun 2020; 11:760. [PMID: 32029733 PMCID: PMC7005308 DOI: 10.1038/s41467-020-14534-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 01/14/2020] [Indexed: 02/07/2023] Open
Abstract
Inflammasomes are important for host defence against pathogens and homeostasis with commensal microbes. Here, we show non-haemolytic enterotoxin (NHE) from the neglected human foodborne pathogen Bacillus cereus is an activator of the NLRP3 inflammasome and pyroptosis. NHE is a non-redundant toxin to haemolysin BL (HBL) despite having a similar mechanism of action. Via a putative transmembrane region, subunit C of NHE initiates binding to the plasma membrane, leading to the recruitment of subunit B and subunit A, thus forming a tripartite lytic pore that is permissive to efflux of potassium. NHE mediates killing of cells from multiple lineages and hosts, highlighting a versatile functional repertoire in different host species. These data indicate that NHE and HBL operate synergistically to induce inflammation and show that multiple virulence factors from the same pathogen with conserved function and mechanism of action can be exploited for sensing by a single inflammasome.
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Affiliation(s)
- Daniel Fox
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Anukriti Mathur
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Yansong Xue
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Yunqi Liu
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Wei Hong Tan
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Shouya Feng
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Abhimanu Pandey
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Chinh Ngo
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Jenni A Hayward
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Ines I Atmosukarto
- Lipotek Pty Ltd. The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Jason D Price
- Lipotek Pty Ltd. The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Matthew D Johnson
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Nadja Jessberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Oberschleißheim, Germany
| | - Avril A B Robertson
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Gaetan Burgio
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - David C Tscharke
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Edward M Fox
- Department of Applied Sciences, Northumbria University, Newcastle Upon Tyne, UK
| | - Denisse L Leyton
- Research School of Biology, The Australian National University, Canberra, Australia.,Medical School, The Australian National University, Canberra, Australia
| | - Nadeem O Kaakoush
- School of Medical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Oberschleißheim, Germany
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Si Ming Man
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia.
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37
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Zeighami H, Nejad-Dost G, Parsadanians A, Daneshamouz S, Haghi F. Frequency of hemolysin BL and non-hemolytic enterotoxin complex genes of Bacillus cereus in raw and cooked meat samples in Zanjan, Iran. Toxicol Rep 2019; 7:89-92. [PMID: 31908970 PMCID: PMC6938900 DOI: 10.1016/j.toxrep.2019.12.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/18/2019] [Accepted: 12/22/2019] [Indexed: 12/14/2022] Open
Abstract
Food safety has emerged as an important global issue with international trade and public health implications. Bacillus cereus is an important cause of food poisoning worldwide. A total of 200 individual meat samples were collected from meat retail outlets and restaurants and investigated the frequency of B. cereus and hemolysin BL (Hbl), non-hemolytic enterotoxin (Nhe) complex genes. The meat samples were immediately homogenized and cultured on Bacillus cereus selective agar and subjected for confirmatory biochemical tests and molecular detection of gyrB, hblA, hblC, hblD, nheA, nheB and nheC genes. A total of 29 (14.5 %) meat samples were positive for the presence of B. cereus. The frequency of B. cereus in raw meat (14.1 %) was similar to cooked beef samples (15 %) (P > 0.05). Twenty six (89.6 %) isolates carried at least one or more enterotoxin genes. We found nheA (58.6 %) and hblD (51.7 %) genes with higher frequency than others. Hemolysin BL complex genes were found in lower frequency than Nhe complex (P > 0.05). Detection of enterotoxigenic B. cereus in meat samples shows a probable risk for public health. Therefore, the reliable molecular methods for monitoring of potentially pathogenic B. cereus are strongly recommended for the routine food examination.
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Affiliation(s)
- Habib Zeighami
- Department of Microbiology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Gholamreza Nejad-Dost
- Department of Microbiology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Angineh Parsadanians
- Department of Microbiology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Shahrzad Daneshamouz
- Department of Microbiology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Fakhri Haghi
- Department of Microbiology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
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38
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Sun Y, Zhang G, Hou X, Xiao S, Yang X, Xie Y, Huang X, Wang F, Mo X, Ding X, Xia L, Hu S. SrfABC Toxin from Xenorhabdus stockiae Induces Cytotoxicity and Apoptosis in HeLa Cells. Toxins (Basel) 2019; 11:toxins11120685. [PMID: 31766712 PMCID: PMC6950479 DOI: 10.3390/toxins11120685] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/11/2019] [Accepted: 11/14/2019] [Indexed: 11/16/2022] Open
Abstract
Our previous study showed that the srfABC operon, which was originally identified in Salmonella enterica as an SsrB-regulated operon clustered with the flagellar class 2 operon, exhibited significant cytotoxicity against insect midgut CF-203 cells and injectable insecticidal activity against Helicoverpa armigera larvae. The srfABC operon was widely distributed among bacteria, which raises the question of their biological roles in different species. In this study, we investigated the cytotoxic effect of SrfABC toxin on mammalian cell lines. When simultaneously expressed in the Escherichia coli cytoplasm, SrfABC exhibited cytotoxicity against all tested mammalian cancer cell lines (B16, 4T-1, Hep-3B, and HeLa) in a dose-dependent manner. Intracellular expression of SrfA-FLAG, SrfB-FLAG, or SrfC-FLAG also resulted in inhibition of proliferation and apoptosis on HeLa cells. When incubated with HeLa cells separately, SrfA, SrfB, and SrfC proteins alone could enter HeLa cells, then induce apoptosis and cytotoxicity. SrfC protein shifts its localization from cytoplasm to nucleus with the aid of SrfA and/or SrfB protein. Although SrfA, SrfB, and SrfC proteins alone exhibited a cytotoxic effect against HeLa cells, all three components were essential for the full cytotoxicity. Native PAGE and co-immunoprecipitation assay demonstrated that SrfA, SrfB, and SrfC proteins could interact with each other and form a heteromeric complex.
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39
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Borba VSD, Paiva Rodrigues MH, Badiale-Furlong E. Impact of Biological Contamination of Rice on Food Safety. FOOD REVIEWS INTERNATIONAL 2019. [DOI: 10.1080/87559129.2019.1683745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Verônica Simões De Borba
- Laboratório de Micotoxinas e Ciência de Alimentos, Escola de Química e Alimentos, Universidade Federal do Rio Grande – FURG, Rio Grande, Brazil
| | - Marcy Heli Paiva Rodrigues
- Laboratório de Micotoxinas e Ciência de Alimentos, Escola de Química e Alimentos, Universidade Federal do Rio Grande – FURG, Rio Grande, Brazil
| | - Eliana Badiale-Furlong
- Laboratório de Micotoxinas e Ciência de Alimentos, Escola de Química e Alimentos, Universidade Federal do Rio Grande – FURG, Rio Grande, Brazil
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40
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Duport C, Alpha-Bazin B, Armengaud J. Advanced Proteomics as a Powerful Tool for Studying Toxins of Human Bacterial Pathogens. Toxins (Basel) 2019; 11:toxins11100576. [PMID: 31590258 PMCID: PMC6832400 DOI: 10.3390/toxins11100576] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 09/27/2019] [Accepted: 09/30/2019] [Indexed: 12/15/2022] Open
Abstract
Exotoxins contribute to the infectious processes of many bacterial pathogens, mainly by causing host tissue damages. The production of exotoxins varies according to the bacterial species. Recent advances in proteomics revealed that pathogenic bacteria are capable of simultaneously producing more than a dozen exotoxins. Interestingly, these toxins may be subject to post-transcriptional modifications in response to environmental conditions. In this review, we give an outline of different bacterial exotoxins and their mechanism of action. We also report how proteomics contributed to immense progress in the study of toxinogenic potential of pathogenic bacteria over the last two decades.
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Affiliation(s)
- Catherine Duport
- SQPOV, UMR0408, Avignon Université, INRA, F-84914 Avignon, France
- Correspondence:
| | - Béatrice Alpha-Bazin
- Laboratoire Innovations technologiques pour la Détection et le Diagnostic (Li2D), Service de Pharmacologie et Immunoanalyse (SPI), CEA, INRA, F-30207 Bagnols sur Cèze, France; (B.A.-B.); (J.A.)
| | - Jean Armengaud
- Laboratoire Innovations technologiques pour la Détection et le Diagnostic (Li2D), Service de Pharmacologie et Immunoanalyse (SPI), CEA, INRA, F-30207 Bagnols sur Cèze, France; (B.A.-B.); (J.A.)
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41
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Berthold-Pluta A, Pluta A, Garbowska M, Stefańska I. Prevalence and toxicity characterization of Bacillus cereus in food products from Poland. Foods 2019; 8:E269. [PMID: 31331094 PMCID: PMC6678163 DOI: 10.3390/foods8070269] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/10/2019] [Accepted: 07/18/2019] [Indexed: 12/14/2022] Open
Abstract
The prevalence of Bacillus cereus in a total of 585 samples of food products (herbs and spices, breakfast cereals, pasta, rice, infant formulas, pasteurized milk, fresh acid and acid/rennet cheeses, mold cheeses and ripening rennet cheeses) marketed in Poland was investigated. The potential of 1022 selected isolates of B. cereus to hydrolyze casein, starch and tributyrin, to ferment lactose, to grow at 7 C/10 days, to produce Nhe and Hbl toxin and to possess the ces gene was verified. B. cereus was found in 38.8% of the analyzed samples, reaching levels from 0.3 to 3.8 log CFU g-1 or mL-1. From the 1022 isolates, 48.8%, 36.0%, 98.9%, 80.0% and 25.0% were capable of fermenting lactose, producing amylase, protease, lipase and growing at 7 C/10 days, respectively, indicating spoilage potentiality. The occurrence of toxigenic B. cereus strains in all tested market products, both of plant (55.8% Hbl(+), 70.7% Nhe(+) and 1.7% ces(+) isolates) and animal origin (84.9% Hbl(+), 82.7% Nhe(+) and 0.9% ces(+) isolates) indicates the possible risk of foodborne infections/intoxications that occur as a result of the possibility of the development of B. cereus in favorable conditions and consumption of these products.
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Affiliation(s)
- Anna Berthold-Pluta
- Division of Milk Biotechnology, Department of Biotechnology, Microbiology and Food Evaluation, Faculty of Food Sciences, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159C St, 02-787 Warsaw, Poland.
| | - Antoni Pluta
- Division of Milk Biotechnology, Department of Biotechnology, Microbiology and Food Evaluation, Faculty of Food Sciences, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159C St, 02-787 Warsaw, Poland
| | - Monika Garbowska
- Division of Milk Biotechnology, Department of Biotechnology, Microbiology and Food Evaluation, Faculty of Food Sciences, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159C St, 02-787 Warsaw, Poland
| | - Ilona Stefańska
- Department of Preclinical Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Ciszewskiego 8 St, 02-787 Warsaw, Poland
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42
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Wilson JS, Churchill-Angus AM, Davies SP, Sedelnikova SE, Tzokov SB, Rafferty JB, Bullough PA, Bisson C, Baker PJ. Identification and structural analysis of the tripartite α-pore forming toxin of Aeromonas hydrophila. Nat Commun 2019; 10:2900. [PMID: 31263098 PMCID: PMC6602965 DOI: 10.1038/s41467-019-10777-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 05/29/2019] [Indexed: 02/07/2023] Open
Abstract
The alpha helical CytolysinA family of pore forming toxins (α-PFT) contains single, two, and three component members. Structures of the single component Eschericia coli ClyA and the two component Yersinia enterolytica YaxAB show both undergo conformational changes from soluble to pore forms, and oligomerization to produce the active pore. Here we identify tripartite α-PFTs in pathogenic Gram negative bacteria, including Aeromonas hydrophila (AhlABC). We show that the AhlABC toxin requires all three components for maximal cell lysis. We present structures of pore components which describe a bi-fold hinge mechanism for soluble to pore transition in AhlB and a contrasting tetrameric assembly employed by soluble AhlC to hide their hydrophobic membrane associated residues. We propose a model of pore assembly where the AhlC tetramer dissociates, binds a single membrane leaflet, recruits AhlB promoting soluble to pore transition, prior to AhlA binding to form the active hydrophilic lined pore. Pore forming toxins (PFTs) form the major group of virulence factors in many pathogenic bacteria. Here the authors identify tripartite α-helical PFTs in pathogenic Gram negative bacteria and structurally characterize AhlABC from Aeromonas hydrophila and propose a model for its pore assembly.
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Affiliation(s)
- Jason S Wilson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK
| | - Alicia M Churchill-Angus
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK
| | - Simon P Davies
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK.,School of Biomedical Sciences, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Svetlana E Sedelnikova
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK
| | - Svetomir B Tzokov
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK
| | - John B Rafferty
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK
| | - Per A Bullough
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK
| | - Claudine Bisson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK.,ISMB, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK
| | - Patrick J Baker
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK.
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44
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Cui Y, Märtlbauer E, Dietrich R, Luo H, Ding S, Zhu K. Multifaceted toxin profile, an approach toward a better understanding of probiotic Bacillus cereus. Crit Rev Toxicol 2019; 49:342-356. [PMID: 31116061 DOI: 10.1080/10408444.2019.1609410] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Strains of the Bacillus cereus group have been widely used as probiotics for human beings, food animals, plants, and environmental remediation. Paradoxically, B. cereus is responsible for both gastrointestinal and nongastrointestinal syndromes and represents an important opportunistic food-borne pathogen. Toxicity assessment is a fundamental issue to evaluate safety of probiotics. Here, we summarize the state of our current knowledge about the toxins of B. cereus sensu lato to be considered for safety assessment of probiotic candidates. Surfactin-like emetic toxin (cereulide) and various enterotoxins including nonhemolytic enterotoxin, hemolysin BL, and cytotoxin K are responsible for food poisoning outbreaks characterized by emesis and diarrhea. In addition, other factors, such as hemolysin II, Certhrax, immune inhibitor A1, and sphingomyelinase, contribute to toxicity and overall virulence of B. cereus.
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Affiliation(s)
- Yifang Cui
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University , Beijing , China.,State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University , Beijing , China
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Ludwig-Maximilians-University Munich , Oberschleißheim , Germany
| | - Richard Dietrich
- Department of Veterinary Sciences, Ludwig-Maximilians-University Munich , Oberschleißheim , Germany
| | - Hailing Luo
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University , Beijing , China
| | - Shuangyang Ding
- National Center for Veterinary Drug Safety Evaluation, College of Veterinary Medicine, China Agricultural University , Beijing , China
| | - Kui Zhu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University , Beijing , China.,National Center for Veterinary Drug Safety Evaluation, College of Veterinary Medicine, China Agricultural University , Beijing , China
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45
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Binding to The Target Cell Surface Is The Crucial Step in Pore Formation of Hemolysin BL from Bacillus cereus. Toxins (Basel) 2019; 11:toxins11050281. [PMID: 31137585 PMCID: PMC6563250 DOI: 10.3390/toxins11050281] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 05/13/2019] [Accepted: 05/16/2019] [Indexed: 12/19/2022] Open
Abstract
A major virulence factor involved in Bacillus cereus food poisoning is the three-component enterotoxin hemolysin BL. It consists of the binding component B and the two lytic components L1 and L2. Studying its mode of action has been challenging, as natural culture supernatants additionally contain Nhe, the second three-component enterotoxin, and purification of recombinant (r) Hbl components has been difficult. In this study, we report on pore-forming, cytotoxic, cell binding and hemolytic activity of recently generated rHbl components expressed in E. coli. It is known that all three Hbl components are necessary for cytotoxicity and pore formation. Here we show that an excess of rHbl B enhances, while an excess of rHbl L1 hinders, the velocity of pore formation. Most rapid pore formation was observed with ratios L2:L1:B = 1:1:10 and 10:1:10. It was further verified that Hbl activity is due to sequential binding of the components B - L1 - L2. Accordingly, all bioassays proved that binding of Hbl B to the cell surface is the crucial step for pore formation and cytotoxic activity. Binding of Hbl B took place within minutes, while apposition of the following L1 and L2 occurred immediately. Further on, applying toxin components simultaneously, it seemed that Hbl L1 enhanced binding of B to the target cell surface. Overall, these data contribute significantly to the elucidation of the mode of action of Hbl, and suggest that its mechanism of pore formation differs substantially from that of Nhe, although both enterotoxin complexes are sequentially highly related.
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46
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Porcine Gastric Mucin Triggers Toxin Production of Enteropathogenic Bacillus cereus. Infect Immun 2019; 87:IAI.00765-18. [PMID: 30745328 DOI: 10.1128/iai.00765-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 01/21/2019] [Indexed: 02/01/2023] Open
Abstract
Enteropathogenic Bacillus cereus causes foodborne infections due to the production of pore-forming enterotoxins in the intestine. Before that, spores have to be ingested, survive the stomach passage, and germinate. Thus, before reaching epithelial cells, B. cereus comes in contact with the intestinal mucus layer. In the present study, different aspects of this interaction were analyzed. Total RNA sequencing revealed major transcriptional changes of B. cereus strain F837/76 upon incubation with porcine gastric mucin (PGM), comprising genes encoding enterotoxins and further putative virulence factors, as well as proteins involved in adhesion to and degradation of mucin. Indeed, PGM was partially degraded by B. cereus via secreted, EDTA-sensitive proteases. The amount of enterotoxins detectable in culture media supplemented with PGM was also clearly increased. Tests of further strains revealed that enhancement of enterotoxin production upon contact with PGM is broadly distributed among B. cereus strains. Interestingly, evidence was found that PGM can also strain-specifically trigger germination of B. cereus spores and that vegetative cells actively move toward mucin. Overall, our data suggest that B. cereus is well adapted to the host environment due to massive transcriptome changes upon contact with PGM, attributing mucin an important and, thus far, neglected role in pathogenesis.
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47
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A multicomponent toxin from Bacillus cereus incites inflammation and shapes host outcome via the NLRP3 inflammasome. Nat Microbiol 2018; 4:362-374. [PMID: 30531979 DOI: 10.1038/s41564-018-0318-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 11/07/2018] [Indexed: 12/25/2022]
Abstract
Host recognition of microbial components is essential in mediating an effective immune response. Cytosolic bacteria must secure entry into the host cytoplasm to facilitate replication and, in doing so, liberate microbial ligands that activate cytosolic innate immune sensors and the inflammasome. Here, we identified a multicomponent enterotoxin, haemolysin BL (HBL), that engages activation of the inflammasome. This toxin is highly conserved among the human pathogen Bacillus cereus. The three subunits of HBL bind to the cell membrane in a linear order, forming a lytic pore and inducing activation of the NLRP3 inflammasome, secretion of interleukin-1β and interleukin-18, and pyroptosis. Mechanistically, the HBL-induced pore results in the efflux of potassium and triggers the activation of the NLRP3 inflammasome. Furthermore, HBL-producing B. cereus induces rapid inflammasome-mediated mortality. Pharmacological inhibition of the NLRP3 inflammasome using MCC950 prevents B. cereus-induced lethality. Overall, our results reveal that cytosolic sensing of a toxin is central to the innate immune recognition of infection. Therapeutic modulation of this pathway enhances host protection against deadly bacterial infections.
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48
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Haddad N, Johnson N, Kathariou S, Métris A, Phister T, Pielaat A, Tassou C, Wells-Bennik MH, Zwietering MH. Next generation microbiological risk assessment—Potential of omics data for hazard characterisation. Int J Food Microbiol 2018; 287:28-39. [DOI: 10.1016/j.ijfoodmicro.2018.04.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 03/31/2018] [Accepted: 04/10/2018] [Indexed: 12/18/2022]
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49
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Bräuning B, Groll M. Structural and Mechanistic Features of ClyA-Like α-Pore-Forming Toxins. Toxins (Basel) 2018; 10:toxins10090343. [PMID: 30142951 PMCID: PMC6162564 DOI: 10.3390/toxins10090343] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 08/16/2018] [Accepted: 08/22/2018] [Indexed: 11/24/2022] Open
Abstract
Recent technological advances have seen increasing numbers of complex structures from diverse pore-forming toxins (PFT). The ClyA family of α-PFTs comprises a broad variety of assemblies including single-, two- and three-component toxin systems. With crystal structures available for soluble subunits of all major groups in this extended protein family, efforts now focus on obtaining molecular insights into physiological pore formation. This review provides an up-to-date discussion on common and divergent structural and functional traits that distinguish the various ClyA family PFTs. Open questions of this research topic are outlined and discussed.
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Affiliation(s)
- Bastian Bräuning
- Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
| | - Michael Groll
- Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
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Riol CD, Dietrich R, Märtlbauer E, Jessberger N. Consumed Foodstuffs Have a Crucial Impact on the Toxic Activity of Enteropathogenic Bacillus cereus. Front Microbiol 2018; 9:1946. [PMID: 30174669 PMCID: PMC6107707 DOI: 10.3389/fmicb.2018.01946] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/31/2018] [Indexed: 11/13/2022] Open
Abstract
Enteropathogenic Bacillus cereus cause diarrhea due to the production of enterotoxins in the intestine. To start this process, spores have to be ingested together with contaminated food and survive the stomach passage. In this study, the influence of consumed foodstuffs on spore survival as well as on cytotoxicity toward colon epithelial cells was investigated. Spore survival of 20 enteropathogenic and apathogenic B. cereus strains during simulated stomach passage was highly strain-specific and did not correlate with the toxic potential. Survival of three tested strains was strain-specifically altered by milk products. Whereas milk, a follow-on formula and rice pudding had only little influence, spores seemed to be protected by milk products with high fat content such as whipped cream and mascarpone. Furthermore, tested milk products decreased the toxic activity of three B. cereus strains toward CaCo-2 cells. Investigating the individual components, lactoferrin, a skim milk powder and vitamins C, B5 and A showed the most inhibiting effects. On the other hand, biotin, vitamin B3 and another skim milk powder even enhanced cytotoxicity. Further studies suggested that these inhibiting effects result only partially from inhibiting cell binding, but rather from blocking the interaction between the single enterotoxin components.
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Affiliation(s)
- Claudia Da Riol
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Nadja Jessberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
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