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Fichant A, Lanceleur R, Hachfi S, Brun-Barale A, Blier AL, Firmesse O, Gallet A, Fessard V, Bonis M. New Approach Methods to Assess the Enteropathogenic Potential of Strains of the Bacillus cereus Group, including Bacillus thuringiensis. Foods 2024; 13:1140. [PMID: 38672813 PMCID: PMC11048917 DOI: 10.3390/foods13081140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/28/2024] Open
Abstract
Bacillus cereus (Bc) is a wide group of Gram-positive and spore-forming bacteria, known to be the etiological agents of various human infections, primarily food poisoning. The Bc group includes enteropathogenic strains able to germinate in the digestive tract and to produce enterotoxins such as Nhe, Hbl, and CytK. One species of the group, Bacillus thuringiensis (Bt), has the unique feature of producing insecticidal crystals during sporulation, making it an important alternative to chemical pesticides to protect crops from insect pest larvae. Nevertheless, several studies have suggested a link between the ingestion of pesticide strains and human cases of food poisoning, calling their safety into question. Consequently, reliable tools for virulence assessment are worth developing to aid decision making in pesticide regulation. Here, we propose complementary approaches based on two biological models, the human intestinal Caco-2 cell line and the insect Drosophila melanogaster, to assess and rank the enteric virulence potency of Bt strains in comparison with other Bc group members. Using a dataset of 48 Bacillus spp. strains, we showed that some Bc group strains, including Bt, were able to induce cytotoxicity in Caco-2 cells with concomitant release of IL-8 cytokine, a landmark of pro-inflammatory response. In the D. melanogaster model, we were able to sort a panel of 39 strains into four different classes of virulence, ranging from no virulence to strong virulence. Importantly, for the most virulent strains, mortality was associated with a loss of intestinal barrier integrity. Interestingly, although strains can share a common toxinotype, they display different degrees of virulence, suggesting the existence of specific mechanisms of virulence expression in vivo in the intestine.
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Affiliation(s)
- Arnaud Fichant
- Laboratory for Food Safety, University Paris-Est, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 94700 Maisons-Alfort, France; (A.F.); (O.F.)
- Université Côte d’Azur, CNRS, INRAE, ISA, 06903 Sophia-Antipolis, France; (S.H.); (A.B.-B.); (A.G.)
| | - Rachelle Lanceleur
- Fougères Laboratory, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 35306 Fougères, France; (R.L.); (A.-L.B.); (V.F.)
| | - Salma Hachfi
- Université Côte d’Azur, CNRS, INRAE, ISA, 06903 Sophia-Antipolis, France; (S.H.); (A.B.-B.); (A.G.)
| | - Alexandra Brun-Barale
- Université Côte d’Azur, CNRS, INRAE, ISA, 06903 Sophia-Antipolis, France; (S.H.); (A.B.-B.); (A.G.)
| | - Anne-Louise Blier
- Fougères Laboratory, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 35306 Fougères, France; (R.L.); (A.-L.B.); (V.F.)
| | - Olivier Firmesse
- Laboratory for Food Safety, University Paris-Est, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 94700 Maisons-Alfort, France; (A.F.); (O.F.)
| | - Armel Gallet
- Université Côte d’Azur, CNRS, INRAE, ISA, 06903 Sophia-Antipolis, France; (S.H.); (A.B.-B.); (A.G.)
| | - Valérie Fessard
- Fougères Laboratory, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 35306 Fougères, France; (R.L.); (A.-L.B.); (V.F.)
| | - Mathilde Bonis
- Laboratory for Food Safety, University Paris-Est, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 94700 Maisons-Alfort, France; (A.F.); (O.F.)
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Calvigioni M, Panattoni A, Biagini F, Donati L, Mazzantini D, Massimino M, Daddi C, Celandroni F, Vozzi G, Ghelardi E. Impact of Bacillus cereus on the Human Gut Microbiota in a 3D In Vitro Model. Microorganisms 2023; 11:1826. [PMID: 37512998 PMCID: PMC10385275 DOI: 10.3390/microorganisms11071826] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/14/2023] [Accepted: 07/16/2023] [Indexed: 07/30/2023] Open
Abstract
In vitro models for culturing complex microbial communities are progressively being used to study the effects of different factors on the modeling of in vitro-cultured microorganisms. In previous work, we validated a 3D in vitro model of the human gut microbiota based on electrospun gelatin scaffolds covered with mucins. The aim of this study was to evaluate the effect of Bacillus cereus, a pathogen responsible for food poisoning diseases in humans, on the gut microbiota grown in the model. Real-time quantitative PCR and 16S ribosomal RNA-gene sequencing were performed to obtain information on microbiota composition after introducing B. cereus ATCC 14579 vegetative cells or culture supernatants. The adhesion of B. cereus to intestinal mucins was also tested. The presence of B. cereus induced important modifications in the intestinal communities. Notably, levels of Proteobacteria (particularly Escherichia coli), Lactobacillus, and Akkermansia were reduced, while abundances of Bifidobacterium and Mitsuokella increased. In addition, B. cereus was able to adhere to mucins. The results obtained from our in vitro model stress the hypothesis that B. cereus is able to colonize the intestinal mucosa by stably adhering to mucins and impacting intestinal microbial communities as an additional pathogenetic mechanism during gastrointestinal infection.
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Affiliation(s)
- Marco Calvigioni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56127 Pisa, Italy
| | - Adelaide Panattoni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56127 Pisa, Italy
| | - Francesco Biagini
- Department of Information Bioengineering, University of Pisa, 56126 Pisa, Italy
- Research Centre "Enrico Piaggio", University of Pisa, 56126 Pisa, Italy
| | - Leonardo Donati
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56127 Pisa, Italy
| | - Diletta Mazzantini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56127 Pisa, Italy
| | - Mariacristina Massimino
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56127 Pisa, Italy
| | - Costanza Daddi
- Department of Information Bioengineering, University of Pisa, 56126 Pisa, Italy
- Research Centre "Enrico Piaggio", University of Pisa, 56126 Pisa, Italy
| | - Francesco Celandroni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56127 Pisa, Italy
| | - Giovanni Vozzi
- Department of Information Bioengineering, University of Pisa, 56126 Pisa, Italy
- Research Centre "Enrico Piaggio", University of Pisa, 56126 Pisa, Italy
| | - Emilia Ghelardi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56127 Pisa, Italy
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Dong Y, Liu J, Nie M, Zhao D, Huang H, Geng J, Wan X, Lu C, Liu Y. Comparative transcriptome combined with morphophysiological analyses revealed the molecular mechanism underlying Tetrahymena thermophila predation-induced antiphage defense in Aeromonas hydrophila. Virulence 2022; 13:1650-1665. [PMID: 36152028 PMCID: PMC9518995 DOI: 10.1080/21505594.2022.2127186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Protozoan predation has been demonstrated to be a strong driving force for bacterial defence strategies in the environment. Our previous study demonstrated that Aeromonas hydrophila NJ-35, which evolved small-colony variants (SCVs), displayed various adaptive traits in response to Tetrahymena thermophila predation, such as enhanced phage resistance. However, the evolutionary mechanisms are largely unknown. In this study, we performed a genome- and transcriptome-wide analysis of the SCV1, representing one strain of the SCVs, for identification of the genes of mutation and altered expression underlying this phage resistance phenotype. Our study demonstrated that phage resistance caused by T. thermophila predation was due to the downregulation of a flagellar biosynthesis regulator, flhF, in SCV1. Interestingly, we confirmed that phage resistance in SCV1 was not straightforwardly attributable to the absence of flagella but to FlhF-mediated secretion of extracellular protein that hinders phage adsorption. This finding improves our understanding of the mechanisms by which A. hydrophila lowers the susceptibility to phage infection under predation pressure, and highlights an important contribution of bacterium–protozoan interactions in driving the adaptive evolution of pathogens in complex environments.
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Affiliation(s)
- Yuhao Dong
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Jin Liu
- Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University, Wuhan, China
| | - Meng Nie
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Dan Zhao
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Hao Huang
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Jinzhu Geng
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Xihe Wan
- Institute of Oceanology and Marine Fisheries, Nantong, China
| | - Chengping Lu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yongjie Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
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Li Y, Chen N, Wu Q, Liang X, Yuan X, Zhu Z, Zheng Y, Yu S, Chen M, Zhang J, Wang J, Ding Y. A Flagella Hook Coding Gene flgE Positively Affects Biofilm Formation and Cereulide Production in Emetic Bacillus cereus. Front Microbiol 2022; 13:897836. [PMID: 35756067 PMCID: PMC9226606 DOI: 10.3389/fmicb.2022.897836] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 05/10/2022] [Indexed: 12/22/2022] Open
Abstract
Bacillus cereus, an important foodborne pathogen, poses a risk to food safety and quality. Robust biofilm formation ability is one of the key properties that is responsible for the food contamination and food poisoning caused by B. cereus, especially the emetic strains. To investigate the mechanism of biofilm formation in emetic B. cereus strains, we screened for the mutants that fail to form biofilms by using random mutagenesis toward B. cereus 892-1, an emetic strain with strong biofilm formation ability. When knocking out flgE, a flagellar hook encoding gene, the mutant showed disappearance of flagellar structure and swimming ability. Further analysis revealed that both pellicle and ring presented defects in the null mutant compared with the wild-type and complementary strains. Compared with the flagellar paralytic strains ΔmotA and ΔmotB, the inhibition of biofilm formation by ΔflgE is not only caused by the inhibition of motility. Interestingly, ΔflgE also decreased the synthesis of cereulide. To our knowledge, this is the first report showing that a flagellar component can both affect the biofilm formation and cereulide production in emetic B. cereus, which can be used as the target to control the biohazard of emetic B. cereus.
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Affiliation(s)
- Yangfu Li
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Nuo Chen
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Qingping Wu
- State Key Laboratory of Applied Microbiology Southern China, Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Xinmin Liang
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Xiaoming Yuan
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Zhenjun Zhu
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China
| | - Yin Zheng
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China
| | - Shubo Yu
- State Key Laboratory of Applied Microbiology Southern China, Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Moutong Chen
- State Key Laboratory of Applied Microbiology Southern China, Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Jumei Zhang
- State Key Laboratory of Applied Microbiology Southern China, Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Juan Wang
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Yu Ding
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
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5
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Calvigioni M, Cara A, Celandroni F, Mazzantini D, Panattoni A, Tirloni E, Bernardi C, Pinotti L, Stella S, Ghelardi E. Characterization of a Bacillus cereus strain associated with a large feed-related outbreak of severe infection in pigs. J Appl Microbiol 2022; 133:1078-1088. [PMID: 35611609 PMCID: PMC9543730 DOI: 10.1111/jam.15636] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 05/12/2022] [Accepted: 05/19/2022] [Indexed: 12/03/2022]
Abstract
Aims Bacillus cereus is often responsible for foodborne diseases and both local and systemic infections in humans. Cases of infection in other mammals are rather rare. In this study, we report a B. cereus feed‐related outbreak that caused the death of 6234 pigs in Italy. Methods and Results Massive doses of a Gram‐positive, spore‐forming bacterium were recovered from the animal feed, faeces of survived pigs and intestinal content of dead ones. The B. cereus MM1 strain was identified by MALDI‐TOF MS and typified by RAPD‐PCR. The isolate was tested for the production of PC‐PLC, proteases, hemolysins and biofilm, for motility, as well as for the presence of genes encoding tissue‐degrading enzymes and toxins. Antimicrobial resistance and pathogenicity in Galleria mellonella larvae were also investigated. Our results show that the isolated B. cereus strain is swimming‐proficient, produces PC‐PLC, proteases, hemolysins, biofilm and carries many virulence genes. The strain shows high pathogenicity in G. mellonella larvae. Conclusions The isolated B. cereus strain demonstrates an aggressive profile of pathogenicity and virulence, being able to produce a wide range of determinants potentially hazardous to pigs' health. Significance and Impact of Study This study highlights the proficiency of B. cereus to behave as a devastating pathogen in swine if ingested at high doses and underlines that more stringent quality controls are needed for livestock feeds and supplements.
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Affiliation(s)
- Marco Calvigioni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Alice Cara
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Francesco Celandroni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Diletta Mazzantini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Adelaide Panattoni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Erica Tirloni
- Department of Health, Animal Science and Food Safety, University of Milan, Italy
| | - Cristian Bernardi
- Department of Health, Animal Science and Food Safety, University of Milan, Italy
| | - Luciano Pinotti
- Department of Health, Animal Science and Food Safety, University of Milan, Italy
| | - Simone Stella
- Department of Health, Animal Science and Food Safety, University of Milan, Italy
| | - Emilia Ghelardi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy.,Research Center Nutraceuticals and Food for Health-Nutrafood, University of Pisa, Italy
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6
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White H, Vos M, Sheppard SK, Pascoe B, Raymond B. Signatures of selection in core and accessory genomes indicate different ecological drivers of diversification among Bacillus cereus clades. Mol Ecol 2022; 31:3584-3597. [PMID: 35510788 PMCID: PMC9324797 DOI: 10.1111/mec.16490] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 03/31/2022] [Accepted: 04/12/2022] [Indexed: 11/30/2022]
Abstract
Bacterial clades are often ecologically distinct, despite extensive horizontal gene transfer (HGT). How selection works on different parts of bacterial pan‐genomes to drive and maintain the emergence of clades is unclear. Focusing on the three largest clades in the diverse and well‐studied Bacillus cereus sensu lato group, we identified clade‐specific core genes (present in all clade members) and then used clade‐specific allelic diversity to identify genes under purifying and diversifying selection. Clade‐specific accessory genes (present in a subset of strains within a clade) were characterized as being under selection using presence/absence in specific clades. Gene ontology analyses of genes under selection revealed that different gene functions were enriched in different clades. Furthermore, some gene functions were enriched only amongst clade‐specific core or accessory genomes. Genes under purifying selection were often clade‐specific, while genes under diversifying selection showed signs of frequent HGT. These patterns are consistent with different selection pressures acting on both the core and the accessory genomes of different clades and can lead to ecological divergence in both cases. Examining variation in allelic diversity allows us to uncover genes under clade‐specific selection, allowing ready identification of strains and their ecological niche.
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Affiliation(s)
- Hugh White
- Centre for Ecology and Conservation, University of Exeter, Penryn campus, Penryn, TR10 9FE, UK
| | - Michiel Vos
- European Centre for Environment and Human Health, University of Exeter Medical School, Environment and Sustainability Institute, Penryn Campus, TR10 9FE, United Kingdom
| | - Samuel K Sheppard
- Milner Centre for Evolution, Department of Biology & Biotechnology, University of Bath, Claverton Down, Bath, UK
| | - Ben Pascoe
- Milner Centre for Evolution, Department of Biology & Biotechnology, University of Bath, Claverton Down, Bath, UK
| | - Ben Raymond
- Centre for Ecology and Conservation, University of Exeter, Penryn campus, Penryn, TR10 9FE, UK
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7
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Schwenk V, Dietrich R, Klingl A, Märtlbauer E, Jessberger N. Characterization of strain-specific Bacillus cereus swimming motility and flagella by means of specific antibodies. PLoS One 2022; 17:e0265425. [PMID: 35298545 PMCID: PMC8929632 DOI: 10.1371/journal.pone.0265425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 03/01/2022] [Indexed: 11/18/2022] Open
Abstract
One of the multiple factors determining the onset of the diarrhoeal disease caused by enteropathogenic Bacillus cereus is the ability of the bacteria to actively move towards the site of infection. This ability depends on flagella, but it also varies widely between different strains. To gain more insights into these strain-specific variations, polyclonal rabbit antisera as well as monoclonal antibodies (mAbs) were generated in this study, which detected recombinant and natural B. cereus flagellin proteins in Western blots as well as in enzyme immunoassays (EIAs). Based on mAb 1A11 and HRP-labelled rabbit serum, a highly specific sandwich EIA was developed. Overall, it could be shown that strain-specific swimming motility correlates with the presence of flagella/flagellin titres obtained in EIAs. Interestingly, mAb 1A11, recognizing an epitope in the N-terminal region of the flagellin protein, proved to inhibit bacterial swimming motility, while the rabbit serum rather decreased growth of selected B. cereus strains. Altogether, powerful tools enabling the in-depth characterization of the strain-specific variations in B. cereus swimming motility were developed.
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Affiliation(s)
- Valerie Schwenk
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Oberschleißheim, Germany
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Oberschleißheim, Germany
| | - Andreas Klingl
- Department of Biology I, Plant Development and Electron Microscopy, Biocenter Ludwig-Maximilians Universität München, Planegg-Martinsried, München, Germany
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Oberschleißheim, Germany
| | - Nadja Jessberger
- Institute for Food Quality and Food Safety, University of Veterinary Medicine Hannover, Hannover, Germany
- * E-mail:
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8
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Bulgari D, Filisetti S, Montagna M, Gobbi E, Faoro F. Pathogenic potential of bacteria isolated from commercial biostimulants. Arch Microbiol 2022; 204:162. [PMID: 35119529 DOI: 10.1007/s00203-022-02769-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 11/08/2022]
Abstract
Microbial-based products are a promising alternative to agrochemicals in sustainable agriculture. However, little is known about their impact on human health even if some of them, i.e., Bacillus and Paenibacillus species, have been increasingly implicated in different human diseases. In this study, 18 bacteria were isolated from 2 commercial biostimulants, and they were genotypically and phenotypically characterized to highlight specific virulence properties. Some isolated bacteria were identified as belonging to the genus Bacillus by BLAST and RDP analyses, a genus in-depth studied for plant growth-promoting ability. Moreover, 16S rRNA phylogenetic analysis showed that seven isolates grouped with Bacillus species while two and four clustered, respectively, with Neobacillus and Peribacillus. Unusually, bacterial strains belonging to Franconibacter and Stenotrophomonas were isolated from biostimulants. Although Bacillus species are generally considered nonpathogenic, most of the species have shown to swim, swarm, and produced biofilms, that can be related to bacterial virulence. The evaluation of toxins encoding genes revealed that five isolates had the potential ability to produce the enterotoxin T. In conclusion, the pathogenic potential of microorganisms included in commercial products should be deeply verified, in our opinion. The approach proposed in this study could help in this crucial step.
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9
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Partridge JD. Surveying a Swarm: Experimental Techniques to Establish and Examine Bacterial Collective Motion. Appl Environ Microbiol 2021;:AEM0185321. [PMID: 34878816 DOI: 10.1128/AEM.01853-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The survival and successful spread of many bacterial species hinges on their mode of motility. One of the most distinct of these is swarming, a collective form of motility where a dense consortium of bacteria employ flagella to propel themselves across a solid surface. Surface environments pose unique challenges, derived from higher surface friction/tension and insufficient hydration. Bacteria have adapted by deploying an array of mechanisms to overcome these challenges. Beyond allowing bacteria to colonize new terrain in the absence of bulk liquid, swarming also bestows faster speeds and enhanced antibiotic resistance to the collective. These crucial attributes contribute to the dissemination, and in some cases pathogenicity, of an array of bacteria. This mini-review highlights; 1) aspects of swarming motility that differentiates it from other methods of bacterial locomotion. 2) Facilitatory mechanisms deployed by diverse bacteria to overcome different surface challenges. 3) The (often difficult) approaches required to cultivate genuine swarmers. 4) The methods available to observe and assess the various facets of this collective motion, as well as the features exhibited by the population as a whole.
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10
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Dietrich R, Jessberger N, Ehling-Schulz M, Märtlbauer E, Granum PE. The Food Poisoning Toxins of Bacillus cereus. Toxins (Basel) 2021; 13:98. [PMID: 33525722 DOI: 10.3390/toxins13020098] [Citation(s) in RCA: 87] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [What about the content of this article? (0)] [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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11
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Smith V, Josefsen M, Lindbäck T, Hegna IK, Finke S, Tourasse NJ, Nielsen-LeRoux C, Økstad OA, Fagerlund A. MogR Is a Ubiquitous Transcriptional Repressor Affecting Motility, Biofilm Formation and Virulence in Bacillus thuringiensis. Front Microbiol 2020; 11:610650. [PMID: 33424814 PMCID: PMC7793685 DOI: 10.3389/fmicb.2020.610650] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 12/01/2020] [Indexed: 12/16/2022] Open
Abstract
Flagellar motility is considered an important virulence factor in different pathogenic bacteria. In Listeria monocytogenes the transcriptional repressor MogR regulates motility in a temperature-dependent manner, directly repressing flagellar- and chemotaxis genes. The only other bacteria known to carry a mogR homolog are members of the Bacillus cereus group, which includes motile species such as B. cereus and Bacillus thuringiensis as well as the non-motile species Bacillus anthracis, Bacillus mycoides and Bacillus pseudomycoides. Furthermore, the main motility locus in B. cereus group bacteria, carrying the genes for flagellar synthesis, appears to be more closely related to L. monocytogenes than to Bacillus subtilis, which belongs to a separate phylogenetic group of Bacilli and does not carry a mogR ortholog. Here, we show that in B. thuringiensis, MogR overexpression results in non-motile cells devoid of flagella. Global gene expression profiling showed that 110 genes were differentially regulated by MogR overexpression, including flagellar motility genes, but also genes associated with virulence, stress response and biofilm lifestyle. Accordingly, phenotypic assays showed that MogR also affects cytotoxicity and biofilm formation in B. thuringiensis. Overexpression of a MogR variant mutated in two amino acids within the putative DNA binding domain restored phenotypes to those of an empty vector control. In accordance, introduction of these mutations resulted in complete loss in MogR binding to its candidate flagellar locus target site in vitro. In contrast to L. monocytogenes, MogR appears to be regulated in a growth-phase dependent and temperature-independent manner in B. thuringiensis 407. Interestingly, mogR was found to be conserved also in non-motile B. cereus group species such as B. mycoides and B. pseudomycoides, which both carry major gene deletions in the flagellar motility locus and where in B. pseudomycoides mogR is the only gene retained. Furthermore, mogR is expressed in non-motile B. anthracis. Altogether this provides indications of an expanded set of functions for MogR in B. cereus group species, beyond motility regulation. In conclusion, MogR constitutes a novel B. thuringiensis pleiotropic transcriptional regulator, acting as a repressor of motility genes, and affecting the expression of a variety of additional genes involved in biofilm formation and virulence.
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Affiliation(s)
- Veronika Smith
- Laboratory for Microbial Dynamics (LaMDa), Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
- Centre for Integrative Microbial Evolution (CIME), Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
| | - Malin Josefsen
- Laboratory for Microbial Dynamics (LaMDa), Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Toril Lindbäck
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Ida K Hegna
- Laboratory for Microbial Dynamics (LaMDa), Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Sarah Finke
- Laboratory for Microbial Dynamics (LaMDa), Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
- Centre for Integrative Microbial Evolution (CIME), Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
| | - Nicolas J Tourasse
- CNRS, INSERM, ARNA, UMR 5320, U1212, University of Bordeaux, Bordeaux, France
| | | | - Ole Andreas Økstad
- Laboratory for Microbial Dynamics (LaMDa), Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
- Centre for Integrative Microbial Evolution (CIME), Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
| | - Annette Fagerlund
- Laboratory for Microbial Dynamics (LaMDa), Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
- Nofima, Norwegian Institute of Food, Fisheries and Aquaculture Research, Ås, Norway
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12
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Coleman SR, Pletzer D, Hancock REW. Contribution of Swarming Motility to Dissemination in a Pseudomonas aeruginosa Murine Skin Abscess Infection Model. J Infect Dis 2020; 224:726-733. [PMID: 33349847 DOI: 10.1093/infdis/jiaa778] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 12/16/2020] [Indexed: 01/21/2023] Open
Abstract
Swarming motility in Pseudomonas aeruginosa is a multicellular adaptation induced by semisolid medium with amino acids as a nitrogen source. By phenotypic screening, we differentiated swarming from other complex adaptive phenotypes, such as biofilm formation, swimming and twitching, by identifying a swarming-specific mutant in ptsP, a metabolic regulator. This swarming-deficient mutant was tested in an acute murine skin abscess infection model. Bacteria were recovered at significantly lower numbers from organs of mice infected with the ∆ptsP mutant. We also tested the synthetic peptide 1018 for activity against different motilities and efficacy in vivo. Treatment with peptide 1018 mimicked the phenotype of the ∆ptsP mutant in vitro, as swarming was inhibited at low concentrations (<2 μg/mL) but not swimming or twitching, and in vivo, as mice had a reduced bacterial load recovered from organs. Therefore, PtsP functions as a regulator of swarming, which in turn contributes to dissemination and colonization in vivo.
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Affiliation(s)
- Shannon R Coleman
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
| | - Daniel Pletzer
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada.,Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Robert E W Hancock
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
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13
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Torres Manno MA, Repizo GD, Magni C, Dunlap CA, Espariz M. The assessment of leading traits in the taxonomy of the Bacillus cereus group. Antonie Van Leeuwenhoek 2020; 113:2223-2242. [PMID: 33179199 DOI: 10.1007/s10482-020-01494-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 10/23/2020] [Indexed: 12/18/2022]
Abstract
Bacillus cereus sensu lato strains (B. cereus group) are widely distributed in nature and have received interest for decades due to their importance in insect pest management, food production and their positive and negative repercussions in human health. Consideration of practical uses such as virulence, physiology, morphology, or ill-defined features have been applied to describe and classify species of the group. However, current comparative studies have exposed inconsistencies between evolutionary relatedness and biological significance among genomospecies of the B. cereus group. Here, the combined analyses of core-based phylogeny and all versus all Average Nucleotide Identity values based on 2116 strains were conducted to update the genomospecies circumscriptions within B. cereus group. These analyses suggested the existence of 57 genomospecies, 37 of which are novel, thus indicating that the taxonomic identities of more than 39% of the analyzed strains should be revised or updated. In addition, we found that whole-genome in silico analyses were suitable to differentiate genomospecies such as B. anthracis, B. cereus and B. thuringiensis. The prevalence of toxin and virulence factors coding genes in each of the genomospecies of the B. cereus group was also examined, using phylogeny-aware methods at wide-genome scale. Remarkably, Cry and emetic toxins, commonly assumed to be associated with B. thuringiensis and emetic B. paranthracis, respectively, did not show a positive correlation with those genomospecies. On the other hand, anthrax-like toxin and capsule-biosynthesis coding genes were positively correlated with B. anthracis genomospecies, despite not being present in all strains, and with presumably non-pathogenic genomospecies. Hence, despite these features have been so far considered relevant for industrial or medical classification of related species of the B. cereus group, they were inappropriate for their circumscription. In this study, genomospecies of the group were accurately affiliated and representative strains defined, generating a rational framework that will allow comparative analysis in epidemiological or ecological studies. Based on this classification the role of specific markers such as Type VII secretion system, cytolysin, bacillolysin, and siderophores such as petrobactin were pointed out for further analysis.
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Affiliation(s)
- Mariano A Torres Manno
- Laboratorio de Biotecnología e Inocuidad de los Alimentos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Municipalidad de Granadero Baigorria, Sede Suipacha 590, Rosario, Santa Fe, Argentina
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR - CONICET), sede FCByF - UNR, Rosario, Santa Fe, Argentina
- Área Estadística y Procesamiento de Datos, Departamento de Matemática y Estadística, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Guillermo D Repizo
- Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Rosario, Argentina
- Laboratorio de Resistencia bacteriana a antimicrobianos, Instituto de Biología Molecular y Celular de Rosario (IBR), sede FCByF - UNR, Rosario, Santa Fe, Argentina
| | - Christian Magni
- Laboratorio de Biotecnología e Inocuidad de los Alimentos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Municipalidad de Granadero Baigorria, Sede Suipacha 590, Rosario, Santa Fe, Argentina
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR - CONICET), sede FCByF - UNR, Rosario, Santa Fe, Argentina
| | - Christopher A Dunlap
- United States Department of Agriculture, Crop Bioprotection Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, 1815 North University Street, Peoria, IL, 61604, USA
| | - Martín Espariz
- Laboratorio de Biotecnología e Inocuidad de los Alimentos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Municipalidad de Granadero Baigorria, Sede Suipacha 590, Rosario, Santa Fe, Argentina.
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR - CONICET), sede FCByF - UNR, Rosario, Santa Fe, Argentina.
- Área Estadística y Procesamiento de Datos, Departamento de Matemática y Estadística, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina.
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14
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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15
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Schwenk V, Riegg J, Lacroix M, Märtlbauer E, Jessberger N. Enteropathogenic Potential of Bacillus thuringiensis Isolates from Soil, Animals, Food and Biopesticides. Foods 2020; 9:foods9101484. [PMID: 33080854 PMCID: PMC7603059 DOI: 10.3390/foods9101484] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/14/2022] Open
Abstract
Despite its benefits as biological insecticide, Bacillus thuringiensis bears enterotoxins, which can be responsible for a diarrhoeal type of food poisoning. Thus, all 24 isolates from foodstuffs, animals, soil and commercially used biopesticides tested in this study showed the genetic prerequisites necessary to provoke the disease. Moreover, though highly strain-specific, various isolates were able to germinate and also to actively move, which are further requirements for the onset of the disease. Most importantly, all isolates could grow under simulated intestinal conditions and produce significant amounts of enterotoxins. Cytotoxicity assays classified 14 isolates as highly, eight as medium and only two as low toxic. Additionally, growth inhibition by essential oils (EOs) was investigated as preventive measure against putatively enteropathogenic B. thuringiensis. Cinnamon Chinese cassia showed the highest antimicrobial activity, followed by citral, oregano and winter savory. In all tests, high strain-specific variations appeared and must be taken into account when evaluating the hazardous potential of B. thuringiensis and using EOs as antimicrobials. Altogether, the present study shows a non-negligible pathogenic potential of B. thuringiensis, independently from the origin of isolation. Generally, biopesticide strains were indistinguishable from other isolates. Thus, the use of these pesticides might indeed increase the risk for consumers’ health. Until complete information about the safety of the applied strains and formulations is available, consumers or manufacturers might benefit from the antimicrobial activity of EOs to reduce the level of contamination.
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Affiliation(s)
- Valerie Schwenk
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (V.S.); (J.R.); (E.M.)
| | - Janina Riegg
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (V.S.); (J.R.); (E.M.)
| | - Monique Lacroix
- Centre Armand-Frappier Santé Biotechnologie, 531, boul. des Prairies, Laval, QC H7V 1B7, Canada;
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (V.S.); (J.R.); (E.M.)
| | - Nadja Jessberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (V.S.); (J.R.); (E.M.)
- Correspondence:
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16
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Bhattacharyya S, Walker DM, Harshey RM. Dead cells release a 'necrosignal' that activates antibiotic survival pathways in bacterial swarms. Nat Commun 2020; 11:4157. [PMID: 32814767 PMCID: PMC7438516 DOI: 10.1038/s41467-020-17709-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 07/14/2020] [Indexed: 01/06/2023] Open
Abstract
Swarming is a form of collective bacterial motion enabled by flagella on the surface of semi-solid media. Swarming populations exhibit non-genetic or adaptive resistance to antibiotics, despite sustaining considerable cell death. Here, we show that antibiotic-induced death of a sub-population benefits the swarm by enhancing adaptive resistance in the surviving cells. Killed cells release a resistance-enhancing factor that we identify as AcrA, a periplasmic component of RND efflux pumps. The released AcrA interacts on the surface of live cells with an outer membrane component of the efflux pump, TolC, stimulating drug efflux and inducing expression of other efflux pumps. This phenomenon, which we call 'necrosignaling', exists in other Gram-negative and Gram-positive bacteria and displays species-specificity. Given that adaptive resistance is a known incubator for evolving genetic resistance, our findings might be clinically relevant to the rise of multidrug resistance.
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Affiliation(s)
- Souvik Bhattacharyya
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - David M Walker
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - Rasika M Harshey
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA.
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17
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Yu XQ, Yan X, Zhang MY, Zhang LQ, He YX. Flavonoids repress the production of antifungal 2,4-DAPG but potentially facilitate root colonization of the rhizobacterium Pseudomonas fluorescens. Environ Microbiol 2020; 22:5073-5089. [PMID: 32363709 DOI: 10.1111/1462-2920.15052] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 04/28/2020] [Indexed: 11/25/2022]
Abstract
In the well-known legume-rhizobia symbiosis, flavonoids released by legume roots induce expression of the Nod factors and trigger early plant responses involved in root nodulation. However, it remains largely unknown how the plant-derived flavonoids influence the physiology of non-symbiotic beneficial rhizobacteria. In this work, we demonstrated that the flavonoids apigenin and/or phloretin enhanced the swarming motility and production of cellulose and curli in Pseudomonas fluorescens 2P24, both traits of which are essential for root colonization. Using a label-free quantitative proteomics approach, we showed that apigenin and phloretin significantly reduced the biosynthesis of the antifungal metabolite 2,4-DAPG and further identified a novel flavonoid-sensing TetR regulator PhlH, which was shown to modulate 2,4-DAPG production by regulating the expression of 2,4-DAPG hydrolase PhlG. Although having similar structures, apigenin and phloretin could also influence different physiological characteristics of P. fluorescens 2P24, with apigenin decreasing the biofilm formation and phloretin inducing expression of proteins involved in the denitrification and arginine fermentation processes. Taken together, our results suggest that plant-derived flavonoids could be sensed by the TetR regulator PhlH in P. fluorescens 2P24 and acts as important signalling molecules that strengthen mutually beneficial interactions between plants and non-symbiotic beneficial rhizobacteria.
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Affiliation(s)
- Xiao-Quan Yu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Xu Yan
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Meng-Yuan Zhang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Li-Qun Zhang
- Department of Plant Pathology, China Agricultural University, Beijing, China
| | - Yong-Xing He
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
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18
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Partridge JD, Harshey RM. Investigating Flagella-Driven Motility in Escherichia coli by Applying Three Established Techniques in a Series. J Vis Exp 2020. [PMID: 32449734 DOI: 10.3791/61364] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Motility is crucial to the survival and success of many bacterial species. Many methodologies exist to exploit motility to understand signaling pathways, to elucidate the function and assembly of flagellar parts, and to examine and understand patterns of movement. Here we demonstrate a combination of three of these methodologies. Motility in soft agar is the oldest, offering a strong selection for isolating gain-of-function suppressor mutations in motility-impaired strains, where motility is restored through a second mutation. The cell-tethering technique, first employed to demonstrate the rotary nature of the flagellar motor, can be used to assess the impact of signaling effectors on the motor speed and its ability to switch rotational direction. The "border-crossing" assay is more recent, where swimming bacteria can be primed to transition into moving collectively as a swarm. In combination, these protocols represent a systematic and powerful approach to identifying components of the motility machinery, and to characterizing their role in different facets of swimming and swarming. They can be easily adapted to study motility in other bacterial species.
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Affiliation(s)
| | - Rasika M Harshey
- Department of Molecular Biosciences, The University of Texas at Austin;
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19
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Mazzantini D, Fonnesu R, Celandroni F, Calvigioni M, Vecchione A, Mrusek D, Bange G, Ghelardi E. GTP-Dependent FlhF Homodimer Supports Secretion of a Hemolysin in Bacillus cereus. Front Microbiol 2020; 11:879. [PMID: 32435240 PMCID: PMC7218170 DOI: 10.3389/fmicb.2020.00879] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/15/2020] [Indexed: 01/09/2023] Open
Abstract
The multidomain (B-NG) protein FlhF, a flagellar biogenesis regulator in several bacteria, is the third paralog of the signal recognition particle (SRP)-GTPases Ffh and FtsY, which are known to drive protein-delivery to the plasma membrane. Previously, we showed that FlhF is required for Bacillus cereus pathogenicity in an insect model of infection, being essential for physiological peritrichous flagellation, for motility, and for the secretion of virulence proteins. Among these proteins, we found that the L2 component of hemolysin BL, one of the most powerful toxins B. cereus produces, was drastically reduced by the FlhF depletion. Herein, we demonstrate that B. cereus FlhF forms GTP-dependent homodimers in vivo since the replacement of residues critical for their GTP-dependent homodimerization alters this ability. The protein directly or indirectly controls flagellation by affecting flagellin-gene transcription and its overproduction leads to a hyperflagellated phenotype. On the other hand, FlhF does not affect the expression of the L2-encoding gene (hblC), but physically binds L2 when in its homodimeric form, recruiting the protein to the plasma membrane for secretion. We additionally show that FlhF overproduction increases L2 secretion and that the FlhF/L2 interaction requires the NG domain of FlhF. Our findings demonstrate the peculiar behavior of B. cereus FlhF, which is required for the correct flagellar pattern and acts as SRP-GTPase in the secretion of a bacterial toxin subunit.
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Affiliation(s)
- Diletta Mazzantini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Rossella Fonnesu
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Francesco Celandroni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Marco Calvigioni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Alessandra Vecchione
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Devid Mrusek
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps University, Marburg, Germany
| | - Gert Bange
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps University, Marburg, Germany
| | - Emilia Ghelardi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
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20
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Abstract
The Bacillus cereus group includes several Bacillus species with closely related phylogeny. The most well-studied members of the group, B. anthracis, B. cereus, and B. thuringiensis, are known for their pathogenic potential. Here, we present the historical rationale for speciation and discuss shared and unique features of these bacteria. Aspects of cell morphology and physiology, and genome sequence similarity and gene synteny support close evolutionary relationships for these three species. For many strains, distinct differences in virulence factor synthesis provide facile means for species assignment. B. anthracis is the causative agent of anthrax. Some B. cereus strains are commonly recognized as food poisoning agents, but strains can also cause localized wound and eye infections as well as systemic disease. Certain B. thuringiensis strains are entomopathogens and have been commercialized for use as biopesticides, while some strains have been reported to cause infection in immunocompromised individuals. In this article we compare and contrast B. anthracis, B. cereus, and B. thuringiensis, including ecology, cell structure and development, virulence attributes, gene regulation and genetic exchange systems, and experimental models of disease.
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21
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Jessberger N, Kranzler M, Da Riol C, Schwenk V, Buchacher T, Dietrich R, Ehling-Schulz M, Märtlbauer E. Assessing the toxic potential of enteropathogenic Bacillus cereus. Food Microbiol 2019; 84:103276. [PMID: 31421762 DOI: 10.1016/j.fm.2019.103276] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/18/2019] [Accepted: 07/20/2019] [Indexed: 12/17/2022]
Abstract
The diarrheal type of food poisoning caused by enteropathogenic Bacillus cereus has been linked to various exotoxins. Best described are the non-hemolytic enterotoxin (Nhe), hemolysin BL (Hbl), and cytotoxin K (CytK). Due to the ubiquitous prevalence of B. cereus in soil and crops and its ability to form highly resistant endospores, contaminations during food production and processing cannot be completely avoided. Although phylogenetically closely related, enteropathogenic B. cereus strains show a high versatility of their toxic potential. Thus, functional tools for evaluating the pathogenic potential are urgently needed in order to predict hazardous food contaminations. As the diarrheal syndrome is the result of a toxico-infection with enterotoxin production in the intestine, the entire passage of the bacteria within the host, from spore survival in the stomach, spore germination, host cell adherence, and motility, to enterotoxin production under simulated intestinal conditions was compared in a panel of 20 strains, including high pathogenic as well as apathogenic ones. This approach resulted in an overarching virulence analysis scheme. In parallel, we searched for potential toxico-specific secreted markers to discriminate low and high pathogenic strains. To this end, we targeted known exotoxins using an easy to implement immunoblotting approach as well as a caseinolytic exoprotease activity assay. Overall, Nhe component B, sphingomyelinase, and exoproteases showed good correlation with the complex virulence analysis scheme and can serve as a template for future fast and easy risk assessment tools to be implemented in routine diagnostic procedures and HACCP studies.
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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.
| | - Markus Kranzler
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210, Vienna, Austria
| | - Claudia Da Riol
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764, Oberschleißheim, Germany
| | - Valerie Schwenk
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764, Oberschleißheim, Germany
| | - Tanja Buchacher
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210, Vienna, Austria
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764, Oberschleißheim, Germany
| | - Monika Ehling-Schulz
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210, Vienna, Austria
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764, Oberschleißheim, Germany
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22
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Abstract
ABSTRACT: Bacillus cereus group includes not pathogenic and high pathogenic species. They are considered as a risk to public health due to foodborne diseases and as an important cause of economic losses to industries due to production of spoilage enzymes. Some researches have been performed in order to assess the possible factors that contribute to put public health into risk because of consumption of food contaminated with viable cells or toxins which have complex mechanisms of production. The control of these bacteria in food is difficult because they are resistant to several processes used in industries. Thus, in this way, this review focused on highlighting the risk due to toxins production by bacteria from B. cereus group in food and the consequences for food safety and dairy industries.
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23
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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24
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Jeßberger N, Rademacher C, Krey VM, Dietrich R, Mohr AK, Böhm ME, Scherer S, Ehling-Schulz M, Märtlbauer E. Simulating Intestinal Growth Conditions Enhances Toxin Production of Enteropathogenic Bacillus cereus. Front Microbiol 2017; 8:627. [PMID: 28446903 PMCID: PMC5388749 DOI: 10.3389/fmicb.2017.00627] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 03/28/2017] [Indexed: 01/17/2023] Open
Abstract
Bacillus cereus is a ubiquitous bacterial pathogen increasingly reported to be the causative agent of foodborne infections and intoxications. Since the enterotoxins linked to the diarrheal form of food poising are foremost produced in the human intestine, the toxic potential of enteropathogenic B. cereus strains is difficult to predict from studies carried out under routine cultivation procedures. In this study, toxigenic properties of a panel of strains (n = 19) of diverse origin were compared using cell culture medium pre-incubated with CaCo-2 cells to mimic intestinal growth conditions. Shortly after contact of the bacteria with the simulated host environment, enterotoxin gene expression was activated and total protein secretion of all strains was accelerated. Although the signal stimulating enterotoxin production still needs to be elucidated, it could be shown that it originated from the CaCo-2 cells. Overall, our study demonstrates that the currently used methods in B. cereus diagnostics, based on standard culture medium, are not allowing a conclusive prediction of the potential health risk related to a certain strain. Thus, these methods should be complemented by cultivation procedures that are simulating intestinal host conditions.
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Affiliation(s)
- Nadja Jeßberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität MünchenOberschleißheim, Germany
| | - Corinna Rademacher
- Functional Microbiology, Department of Pathobiology, Institute of Microbiology, University of Veterinary Medicine ViennaVienna, Austria
| | - Viktoria M Krey
- Lehrstuhl für Mikrobielle Ökologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung, Wissenschaftszentrum Weihenstephan, Technische Universität MünchenFreising, Germany
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität MünchenOberschleißheim, Germany
| | - Ann-Katrin Mohr
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität MünchenOberschleißheim, Germany
| | - Maria-Elisabeth Böhm
- Lehrstuhl für Mikrobielle Ökologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung, Wissenschaftszentrum Weihenstephan, Technische Universität MünchenFreising, Germany
| | - Siegfried Scherer
- Lehrstuhl für Mikrobielle Ökologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung, Wissenschaftszentrum Weihenstephan, Technische Universität MünchenFreising, Germany
| | - Monika Ehling-Schulz
- Functional Microbiology, Department of Pathobiology, Institute of Microbiology, University of Veterinary Medicine ViennaVienna, Austria
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität MünchenOberschleißheim, Germany
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