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Zhang Y, Li H, Wang F, Liu C, Reddy GVP, Li H, Li Z, Sun Y, Zhao Z. Discovery of a new highly pathogenic toxin involved in insect sepsis. Microbiol Spectr 2023; 11:e0142223. [PMID: 37787562 PMCID: PMC10715044 DOI: 10.1128/spectrum.01422-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 08/07/2023] [Indexed: 10/04/2023] Open
Abstract
IMPORTANCE As a current biocontrol resource, entomopathogenic nematodes and their symbiotic bacterium can produce many toxin factors to trigger insect sepsis, having the potential to promote sustainable pest management. In this study, we found Steinernema feltiae and Xenorhabdus bovienii were highly virulent against the insects. After infective juvenile injection, Galleria mellonella quickly turned black and softened with increasing esterase activity. Simultaneously, X. bovienii attacked hemocytes and released toxic components, resulting in extensive hemolysis and sepsis. Then, we applied high-resolution mass spectrometry-based metabolomics and found multiple substances were upregulated in the host hemolymph. We found extremely hazardous actinomycin D produced via 3-hydroxyanthranilic acid metabolites. Moreover, a combined transcriptomic analysis revealed that gene expression of proteins associated with actinomycin D was upregulated. Our research revealed actinomycin D might be responsible for the infestation activity of X. bovienii, indicating a new direction for exploring the sepsis mechanism and developing novel biotic pesticides.
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Affiliation(s)
- Yuan Zhang
- MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, China
| | - Hao Li
- MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, China
| | - Fang Wang
- Institute of Plant Protection, Ningxia Academy of Agricultural and Forestry Sciences, Yinchuan, China
| | - Chang Liu
- Institute of Plant Protection, Ningxia Academy of Agricultural and Forestry Sciences, Yinchuan, China
| | - Gadi V. P. Reddy
- Department of Entomology, Lousiana State University, Baton Rouge, Los Angeles, USA
| | - Hu Li
- MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, China
- Sanya Institute of China Agricultural University, China Agricultural University, Sanya, China
| | - Zhihong Li
- MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, China
- Sanya Institute of China Agricultural University, China Agricultural University, Sanya, China
| | - Yucheng Sun
- Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Zihua Zhao
- MARA Key Laboratory of Surveillance and Management for Plant Quarantine Pests, College of Plant Protection, China Agricultural University, Beijing, China
- Sanya Institute of China Agricultural University, China Agricultural University, Sanya, China
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Pothula R, Lee MW, Patricia Stock S. Type 6 Secretion System components hcp and vgrG support mutualistic partnership between Xenorhabdus bovienii symbiont and Steinernema jollieti host. J Invertebr Pathol 2023; 198:107925. [PMID: 37087093 DOI: 10.1016/j.jip.2023.107925] [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: 10/17/2022] [Revised: 04/11/2023] [Accepted: 04/16/2023] [Indexed: 04/24/2023]
Abstract
Xenorhabdus, like other Gram-negative bacteria, possesses a Type 6 Secretion System (T6SS) which acts as a contact-dependent molecular syringe, delivering diverse proteins (effectors) directly into other cells. The number of T6SS loci encoded in Xenorhabdus genomes are variable both at the inter and intraspecific level. Some environmental isolates of Xenorhabdus bovienii, encode at least one T6SS locus while others possess two loci. Previous work conducted by our team demonstrated that X. bovienii [Jollieti strain SS-2004], which has two T6SSs (T6SS-1 and T6SS-2), hcp genes are required for biofilm formation. Additionally, while T6SS-1 hcp gene plays a role in the antibacterial competition, T6SS-2 hcp does not. In this study, we tested the hypothesis that vgrG genes are also involved in mutualistic and pathogenic interactions. For this purpose, targeted mutagenesis together with wet lab experiments including colonization, competition, biofilm, and virulence experiments, were carried out to assess the role of vgrG in the mutualistic and antagonistic interactions in the life cycle of XBJ. Our results revealed that vgrG genes are not required for biofilm formation but play a role in outcompeting other Xenorhabdus bacteria. Additionally, both vgrG and hcp genes are required to fully colonize the nematode host. We also demonstrated that hcp and vgrG genes in both T6SS clusters are needed to support the reproductive fitness of the nematodes. Overall, results from this study revealed that in X. bovieni jollieti strain, the twoT6SS clusters play an important role in the fitness of the nematodes in relation to colonization and reproduction. These results lay a foundation for further investigations on the functional significance of T6SSs in the mutualistic and pathogenic lifecycle of Xenorhabdus spp.
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Affiliation(s)
- Ratnasri Pothula
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, United States
| | - Min-Woo Lee
- Corn, Soybean, and Wheat Quality Research Lab, USDA-ARS Wooster, OH, United States
| | - S Patricia Stock
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, United States; College of Agriculture, California State University, Chico, CA, United States.
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Baazeem A, Alotaibi SS, Khalaf LK, Kumar U, Zaynab M, Alharthi S, Darwish H, Alghamdi A, Jat SK, Al-Barty A, Albogami B, Noureldeen A, Ravindran B. Identification and environment-friendly biocontrol potential of five different bacteria against Aphis punicae and Aphis illinoisensis (Hemiptera: Aphididae). Front Microbiol 2022; 13:961349. [PMID: 36386662 PMCID: PMC9640465 DOI: 10.3389/fmicb.2022.961349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Accepted: 09/26/2022] [Indexed: 11/25/2022] Open
Abstract
The current work is aimed at isolating and identifying new Entomopathogenic bacterium (EPB) strains associated with Steinernema feltiae and assessing the EPB’s biocontrol potential on Aphis punicae and Aphis illinoisensis adults in the laboratory. From S. feltiae, five bacterial isolates were isolated and molecularly characterized. Lysinibacillus xylanilyticus strain TU-2, Lysinibacillus xylanilyticus strain BN-13, Serratia liquefaciens strain TU-6, Stenotrophomonas tumulicola strain T5916-2-1b, and Pseudochrobactrum saccharolyticum strain CCUG are the strains. Pathogenicity tests demonstrated that bacterial cells were more toxic against the two aphid species than bacterial cell-free supernatants. S. tumulicola strain T5916-2-1b cells and filtrate were reported to have the strongest potential to kill A. punicae and A. illinoisensis individuals within 6 h after treatment, with 100% mortality of both insects 24 and 48 h after treatment. Based on the results of the study, it looked like endogenous Steinernema-associated EPB could be used directly as a biocontrol agent for A. punicae and A. illinoisensis.
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Affiliation(s)
- Alaa Baazeem
- Department of Biology, College of Science, Taif University, Taif, Saudi Arabia
| | - Saqer S. Alotaibi
- Department of Biotechnology, College of Science, Taif University, Taif, Saudi Arabia
| | - Luaay Kahtan Khalaf
- Department of Plant Protection, College of Agricultural Engineering Science, University of Baghdad, Baghdad, Iraq
| | - Uttam Kumar
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Madiha Zaynab
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Sciences, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong, China
| | - Sarah Alharthi
- Department of Chemistry, College of Science, Taif University, Taif, Saudi Arabia
| | - Hadeer Darwish
- Department of Biotechnology, College of Science, Taif University, Taif, Saudi Arabia
| | - Akram Alghamdi
- Department of Biology, College of Science, Taif University, Taif, Saudi Arabia
| | - Suresh Kumar Jat
- Department of Plant Protection, College of Horticulture and Forestry, Agriculture University, Kota, India
| | - Amal Al-Barty
- Department of Biology, College of Science, Taif University, Taif, Saudi Arabia
| | - Bander Albogami
- Department of Biology, College of Science, Taif University, Taif, Saudi Arabia
| | - Ahmed Noureldeen
- Department of Biology, College of Science, Taif University, Taif, Saudi Arabia
- *Correspondence: Ahmed Noureldeen,
| | - Balasubramani Ravindran
- Department of Environmental Energy and Engineering, Kyonggi University, Suwon, South Korea
- Department of Medical Biotechnology and Integrative Physiology, Institute of Biotechnology, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Thandalam, Chennai, Tamil Nadu, India
- Balasubramani Ravindran,
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Alotaibi SS, Darwish H, Zaynab M, Alharthi S, Alghamdi A, Al-Barty A, Asif M, Wahdan RH, Baazeem A, Noureldeen A. Isolation, Identification, and Biocontrol Potential of Entomopathogenic Nematodes and Associated Bacteria against Virachola livia (Lepidoptera: Lycaenidae) and Ectomyelois ceratoniae (Lepidoptera: Pyralidae). BIOLOGY 2022; 11:295. [PMID: 35205161 PMCID: PMC8869210 DOI: 10.3390/biology11020295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 02/09/2022] [Accepted: 02/10/2022] [Indexed: 11/17/2022]
Abstract
Virachola livia (Lepidoptera: Lycaenidae) and Ectomyelois ceratoniae (Lepidoptera: Pyralidae) are the key pests of pomegranates in Saudi Arabia that are managed mainly using broad-spectrum pesticides. Interactions between the entomopathogenic nematodes (EPNs) Steinernematids, and Heterorhabditids, and their entomopathogenic bacterial symbionts (EPBs) have long been considered monoxenic 2-partner associations responsible for killing insects and, therefore, are widely used in insect pest biocontrol. However, there are limited reports identifying such organisms in Taif, Saudi Arabia. The current study aimed to identify the EPNs and their associated bacteria isolated from Taif, Saudi Arabia, and evaluate their biocontrol potential on third instar larvae of V. livia and E. ceratoniae under laboratory conditions. A total of 35 EPN isolates belonging to Steinernema (20) and Heterorhabditis (15) were recovered from 320 soil samples. Twenty-six isolates of symbiotic or associated bacteria were isolated from EPNs and molecularly identified as Xenorhabdus (6 isolates), Photorhabdus (4 isolates), Pseudomonas (7), or Stenotrophomonas (9). A pathogenicity assay revealed that Steinernema spp. were more virulent than Heterorhabditis spp. against the two pomegranate insects, with LC50 values of 18.5 and 13.6 infective juveniles (IJs)/larva of V. livia for Steinernema spp. and 52 and 32.4 IJs/larva of V. livia for Heterorhabditis spp. at 48 and 72 h post-treatment, respectively. Moreover, LC50 values of 9 and 6.6 IJs/larva (Steinernema spp.) and 34.4 and 26.6 IJs/larva (Heterorhabditis spp.) were recorded for E. ceratoniae larvae at 48 and 72 h post-treatment. In addition, the EPB Stenotrophomonas maltophilia CQ1, isolated from Steinernema spp., surpassed Pseudomonas mosselii SJ10, associated with Heterorhabditis spp., in their ability to kill V. livia or E. ceratoniae larvae within 6 h post-application, resulting in 100% mortality in both insects after 24 and 48 h of exposure. We conclude that either application of EPNs' IJs or their associated EPBs could serve as potential biocontrol agents for V. livia and E. ceratoniae.
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Affiliation(s)
- Saqer S. Alotaibi
- Department of Biotechnology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia;
| | - Hadeer Darwish
- Department of Biotechnology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia;
| | - Madiha Zaynab
- Shenzhen Key Laboratory of Marine Bioresource & Eco-Environmental Sciences, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518107, China;
| | - Sarah Alharthi
- Department of Chemistry, College of Science, Taif University, P.O. BOX 11099, Taif 21944, Saudi Arabia;
| | - Akram Alghamdi
- Department of Biology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia; (A.A.); (A.A.-B.); (A.B.); (A.N.)
| | - Amal Al-Barty
- Department of Biology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia; (A.A.); (A.A.-B.); (A.B.); (A.N.)
| | - Mohd Asif
- Regional Ayurveda Research Institute (CCRAS), Ranikhet 263645, Uttarakhand, India;
| | - Rania H. Wahdan
- Agricultural Research Center, Department of Nematode Diseases Research, Plant Pathology Research Institute, Giza 12619, Egypt;
| | - Alaa Baazeem
- Department of Biology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia; (A.A.); (A.A.-B.); (A.B.); (A.N.)
| | - Ahmed Noureldeen
- Department of Biology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia; (A.A.); (A.A.-B.); (A.B.); (A.N.)
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Maher AMD, Asaiyah M, Quinn S, Burke R, Wolff H, Bode HB, Griffin CT. Competition and Co-existence of Two Photorhabdus Symbionts with a Nematode Host. MICROBIAL ECOLOGY 2021; 81:223-239. [PMID: 32827089 DOI: 10.1007/s00248-020-01573-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 08/05/2020] [Indexed: 06/11/2023]
Abstract
Photorhabdus spp. (Enterobacteriales: Morganellaceae) occur exclusively as symbionts of Heterorhabditis nematodes for which they provide numerous services, including killing insects and providing nutrition and defence within the cadavers. Unusually, two species (Photorhabdus cinerea and Photorhabdus temperata) associate with a single population of Heterorhabditis downesi at a dune grassland site. Building on previous work, we investigated competition between these two Photorhabdus species both at the regional (between insects) and local (within insect) level by trait comparison and co-culture experiments. There was no difference between the species with respect to supporting nematode reproduction and protection of cadavers against invertebrate scavengers, but P. cinerea was superior to P. temperata in several traits: faster growth rate, greater antibacterial and antifungal activity and colonisation of a higher proportion of nematodes in co-culture. Moreover, where both bacterial symbionts colonised single nematode infective juveniles, P. cinerea tended to dominate in numbers. Differences between Photorhabdus species were detected in the suite of secondary metabolites produced: P. temperata produced several compounds not produced by P. cinerea including anthraquinone pigments. Bioluminescence emitted by P. temperata also tended to be brighter than that from P. cinerea. Bioluminescence and pigmentation may protect cadavers against scavengers that rely on sight. We conclude that while P. cinerea may show greater local level (within-cadaver) competitive success, co-existence of the two Photorhabdus species in the spatially heterogeneous environment of the dunes is favoured by differing specialisations in defence of the cadaver against differing locally important threats.
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Affiliation(s)
- Abigail M D Maher
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland
| | - Mohamed Asaiyah
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland
| | - Sarajane Quinn
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland
| | - Riona Burke
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland
| | - Hendrik Wolff
- Molecular Biotechnology, Department of Biosciences, Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University Frankfurt, and Senckenberg Gesellschaft für Naturforschung, Frankfurt, Germany
| | - Helge B Bode
- Molecular Biotechnology, Department of Biosciences, Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University Frankfurt, and Senckenberg Gesellschaft für Naturforschung, Frankfurt, Germany
| | - Christine T Griffin
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland.
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Yu B, Wang Z, Liu S, Liu X, Gou R. The data dimensionality reduction and bad data detection in the process of smart grid reconstruction through machine learning. PLoS One 2020; 15:e0237994. [PMID: 33027298 PMCID: PMC7540890 DOI: 10.1371/journal.pone.0237994] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/07/2020] [Indexed: 11/24/2022] Open
Abstract
To detect false data injection attacks (FDIAs) in power grid reconstruction and solve the problem of high data dimension and bad abnormal data processing in the power system, thereby achieving safe and stable operation of the power grid system, this study introduces machine learning methods to explore the detection of FDIAs. First, through the utilization of the standard IEEE node system and the simulation of FDIAs under the condition of non-complete topology information, the construction of the attack data set is completed, and the MatPower tool is applied to simulate and analyze the data set. Second, based on the isolated Forest (iForest) abnormal score data processing algorithm combined with the Local Linear Embedding (LLE) data dimensionality reduction method, an algorithm for data feature extraction is constructed. Finally, based on the combination of the Convolutional Neural Network (CNN) and the Gated Recurrent Unit (GRU) network, an algorithm model for FDIAs detection is constructed. The results show that in the IEEE14-bus node and IEEE118-bus node systems, the overall distribution of the state estimated before and after the attack vector injection is consistent with the initial value. In the iFores algorithm, the number of iTree and the number of samples affect the extraction of abnormal score data. When the number of iTree n is determined to be 100, and the corresponding number of samples w is determined to be 10, the algorithm has the best detection effect. The FDIAs detection algorithm model based on CNN-GRU shows good detection effects under high attack intensity, with an accuracy rate of more than 95%, and its performance is better than other traditional detection algorithms. In this study, the bad data detection model based on deep learning has an active role in the realization of the safe and stable operation of the smart grid.
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Affiliation(s)
- Bo Yu
- State Grid Ningxia Electric Power, Eco-Tech Research Institute, Yinchuan, China
| | - Zheng Wang
- State Grid Ningxia Electric Power, Eco-Tech Research Institute, Yinchuan, China
| | - Shangke Liu
- State Grid Ningxia Electric Power, Eco-Tech Research Institute, Yinchuan, China
| | - Xiaomin Liu
- State Grid Ningxia Electric Power, Eco-Tech Research Institute, Yinchuan, China
| | - Ruixin Gou
- State Grid Ningxia Electric Power, Eco-Tech Research Institute, Yinchuan, China
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Kochanowsky RM, Bradshaw C, Forlastro I, Stock SP. Xenorhabdus bovienii strain jolietti uses a type 6 secretion system to kill closely related Xenorhabdus strains. FEMS Microbiol Ecol 2020; 96:fiaa073. [PMID: 32558899 PMCID: PMC7353953 DOI: 10.1093/femsec/fiaa073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 04/21/2020] [Indexed: 01/25/2023] Open
Abstract
Xenorhabdus bovienii strain jolietti (XBJ) is a Gram-negative bacterium that interacts with several organisms as a part of its life cycle. It is a beneficial symbiont of nematodes, a potent pathogen of a wide range of soil-dwelling insects and also has the ability to kill soil- and insect-associated microbes. Entomopathogenic Steinernema nematodes vector XBJ into insects, releasing the bacteria into the insect body cavity. There, XBJ produce a variety of insecticidal toxins and antimicrobials. XBJ's genome also encodes two separate Type Six Secretion Systems (T6SSs), structures that allow bacteria to inject specific proteins directly into other cells, but their roles in the XBJ life cycle are mostly unknown. To probe the function of these T6SSs, we generated mutant strains lacking the key structural protein Hcp from each T6SS and assessed phenotypes related to different parts of XBJ's life cycle. Here we demonstrate that one of the T6SSs is more highly expressed in in vitro growth conditions and has antibacterial activity against other Xenorhabdus strains, and that the two T6SSs have a redundant role in biofilm formation.
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Affiliation(s)
- Rebecca M Kochanowsky
- School of Animal and Comparative Biomedical Sciences, University of Arizona, 1117 E. Lowell St., Tucson, AZ 85721, USA
- Center for Insect Science, University of Arizona, 1007 E. Lowell St., Tucson, AZ 85721, USA
| | - Christine Bradshaw
- School of Animal and Comparative Biomedical Sciences, University of Arizona, 1117 E. Lowell St., Tucson, AZ 85721, USA
| | - Isabel Forlastro
- School of Animal and Comparative Biomedical Sciences, University of Arizona, 1117 E. Lowell St., Tucson, AZ 85721, USA
| | - S Patricia Stock
- School of Animal and Comparative Biomedical Sciences, University of Arizona, 1117 E. Lowell St., Tucson, AZ 85721, USA
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Ogier JC, Pagès S, Frayssinet M, Gaudriault S. Entomopathogenic nematode-associated microbiota: from monoxenic paradigm to pathobiome. MICROBIOME 2020; 8:25. [PMID: 32093774 PMCID: PMC7041241 DOI: 10.1186/s40168-020-00800-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 02/05/2020] [Indexed: 06/10/2023]
Abstract
BACKGROUND The holistic view of bacterial symbiosis, incorporating both host and microbial environment, constitutes a major conceptual shift in studies deciphering host-microbe interactions. Interactions between Steinernema entomopathogenic nematodes and their bacterial symbionts, Xenorhabdus, have long been considered monoxenic two partner associations responsible for the killing of the insects and therefore widely used in insect pest biocontrol. We investigated this "monoxenic paradigm" by profiling the microbiota of infective juveniles (IJs), the soil-dwelling form responsible for transmitting Steinernema-Xenorhabdus between insect hosts in the parasitic lifecycle. RESULTS Multigenic metabarcoding (16S and rpoB markers) showed that the bacterial community associated with laboratory-reared IJs from Steinernema carpocapsae, S. feltiae, S. glaseri and S. weiseri species consisted of several Proteobacteria. The association with Xenorhabdus was never monoxenic. We showed that the laboratory-reared IJs of S. carpocapsae bore a bacterial community composed of the core symbiont (Xenorhabdus nematophila) together with a frequently associated microbiota (FAM) consisting of about a dozen of Proteobacteria (Pseudomonas, Stenotrophomonas, Alcaligenes, Achromobacter, Pseudochrobactrum, Ochrobactrum, Brevundimonas, Deftia, etc.). We validated this set of bacteria by metabarcoding analysis on freshly sampled IJs from natural conditions. We isolated diverse bacterial taxa, validating the profile of the Steinernema FAM. We explored the functions of the FAM members potentially involved in the parasitic lifecycle of Steinernema. Two species, Pseudomonas protegens and P. chlororaphis, displayed entomopathogenic properties suggestive of a role in Steinernema virulence and membership of the Steinernema pathobiome. CONCLUSIONS Our study validates a shift from monoxenic paradigm to pathobiome view in the case of the Steinernema ecology. The microbial communities of low complexity associated with EPNs will permit future microbiota manipulation experiments to decipher overall microbiota functioning in the infectious process triggered by EPN in insects and, more generally, in EPN ecology.
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Affiliation(s)
| | - Sylvie Pagès
- DGIMI, INRAe-Université de Montpellier, 34095, Montpellier, France
| | - Marie Frayssinet
- DGIMI, INRAe-Université de Montpellier, 34095, Montpellier, France
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Sajnaga E, Kazimierczak W. Evolution and taxonomy of nematode-associated entomopathogenic bacteria of the genera Xenorhabdus and Photorhabdus: an overview. Symbiosis 2020. [DOI: 10.1007/s13199-019-00660-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
AbstractEntomopathogenic bacteria from the genera Photorhabdus and Xenorhabdus are closely related Gram-negative bacilli from the family Enterobacteriaceae (γ-Proteobacteria). They establish obligate mutualistic associations with soil nematodes from the genera Steinernema and Heterorhabditis to facilitate insect pathogenesis. The research of these two bacterial genera is focused mainly on their unique interactions with two different animal hosts, i.e. nematodes and insects. So far, studies of the mutualistic bacteria of nematodes collected from around the world have contributed to an increase in the number of the described Xenorhabdus and Photorhabdus species. Recently, the classification system of entomopatogenic nematode microsymbionts has undergone profound revision and now 26 species of the genus Xenorhabdus and 19 species of the genus Photorhabdus have been identified. Despite their similar life style and close phylogenetic origin, Photorhabdus and Xenorhabdus bacterial species differ significantly in e.g. the nematode host range, symbiotic strategies for parasite success, and arrays of released antibiotics and insecticidal toxins. As the knowledge of the diversity of entomopathogenic nematode microsymbionts helps to enable the use thereof, assessment of the phylogenetic relationships of these astounding bacterial genera is now a major challenge for researchers. The present article summarizes the main information on the taxonomy and evolutionary history of Xenorhabdus and Photorhabdus, entomopathogenic nematode symbionts.
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Ciezki K, Wesener S, Jaber D, Mirza S, Forst S. ngrA-dependent natural products are required for interspecies competition and virulence in the insect pathogenic bacterium Xenorhabdus szentirmaii. MICROBIOLOGY-SGM 2019; 165:538-553. [PMID: 30938671 DOI: 10.1099/mic.0.000793] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Xenorhabdus species are symbionts of entomopathogenic nematodes and pathogens of susceptible insects. Nematodes enter insect hosts and perforate the midgut to invade the haemocoel where Xenorhabdus bacteria are released transitioning to their pathogenic stage. During nematode invasion microbes from the insect gut translocate into the haemocoel. Different species of nematodes carrying specific strains of Xenorhabdus can also invade the same insect. Xenorhabdus species thereby compete for nutrients and space with both related strains and non-related gut microbes. While Xenorhabdus species produce diverse antimicrobial compounds in complex media, their functions in insect hosts are not well understood. We show that Xenorhabdus szentirmaii produced ngrA-dependent antibiotics that were active against both gut-derived microbes and Xenorhabdus nematophila whereas antibiotics of X. nematophila were not active against X. szentirmaii. X. nematophila growth was inhibited in co-cultures with wild-type X. szentirmaii in medium that mimics insect haemolymph. An antibiotic-deficient strain of X. szentirmaii was created by inactivating the ngrA gene that encodes the enzyme that attaches the 4' phosphopantetheinyl moiety to non-ribosomal peptide synthetases involved in antibiotic biosynthesis. X. nematophila growth was not inhibited in co-cultures with the ngrA strain. The growth of X. nematophila was suppressed in Manduca sexta co-injected with wild-type X. szentirmaii and X. nematophila. In contrast, growth of X. nematophila was not suppressed in M. sexta co-injected with the ngrA strain. Two unique compounds were detected by MALDI-TOF MS analysis in haemolymph infected with the wild-type but not with the ngrA strain. Finally, killing of M. sexta was delayed in insects infected with the ngrA strain. These findings indicate that in the insect host X. szentirmaii produces ngrA-dependent products involved in both interspecies competition and virulence.
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Affiliation(s)
- Kristin Ciezki
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, USA
| | - Shane Wesener
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, USA
| | - Danny Jaber
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, USA
| | - Shama Mirza
- Shimadzu Laboratory for Advanced and Applied Analytical Chemistry, University of Wisconsin, Milwaukee, WI, USA
| | - Steven Forst
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, USA
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Stock SP. Partners in crime: symbiont-assisted resource acquisition in Steinernema entomopathogenic nematodes. CURRENT OPINION IN INSECT SCIENCE 2019; 32:22-27. [PMID: 31113627 DOI: 10.1016/j.cois.2018.10.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Revised: 10/15/2018] [Accepted: 10/17/2018] [Indexed: 06/09/2023]
Abstract
Entomopathogenic nematodes in the genus Steinernema (Nematoda: Steinernematidae) have a mutualistic relationship with Xenorhabdus bacteria (Gram-negative Enterobacteriaceae). This partnership however, is pathogenic to a wide range of insect species. Because of their potent insecticidal ability, they have successfully been implemented in biological control and integrated pest management programs worldwide. Steinernema-Xenorhabdus-insect partnerships are extremely diverse and represent a model system in ecology and evolution to investigate symbioses between invertebrates and microbes. The reproductive fitness of the nematode-bacterium partnership is tightly associated, and maintenance of their virulence is critical to the conversion of the insect host as a suitable environment where this partnership can be perpetuated.
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12
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Eugenia Nuñez-Valdez M, Lanois A, Pagès S, Duvic B, Gaudriault S. Inhibition of Spodoptera frugiperda phenoloxidase activity by the products of the Xenorhabdus rhabduscin gene cluster. PLoS One 2019; 14:e0212809. [PMID: 30794697 PMCID: PMC6386379 DOI: 10.1371/journal.pone.0212809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 02/08/2019] [Indexed: 12/15/2022] Open
Abstract
We evaluated the impact of bacterial rhabduscin synthesis on bacterial virulence and phenoloxidase inhibition in a Spodoptera model. We first showed that the rhabduscin cluster of the entomopathogenic bacterium Xenorhabdus nematophila was not necessary for virulence in the larvae of Spodoptera littoralis and Spodoptera frugiperda. Bacteria with mutations affecting the rhabduscin synthesis cluster (ΔisnAB and ΔGT mutants) were as virulent as the wild-type strain. We then developed an assay for measuring phenoloxidase activity in S. frugiperda and assessed the ability of bacterial culture supernatants to inhibit the insect phenoloxidase. Our findings confirm that the X. nematophila rhabduscin cluster is required for the inhibition of S. frugiperda phenoloxidase activity. The X. nematophila ΔisnAB mutant was unable to inhibit phenoloxidase, whereas ΔGT mutants displayed intermediate levels of phenoloxidase inhibition relative to the wild-type strain. The culture supernatants of Escherichia coli and of two entomopathogenic bacteria, Serratia entomophila and Xenorhabdus poinarii, were unable to inhibit S. frugiperda phenoloxidase activity. Heterologous expression of the X. nematophila rhabduscin cluster in these three strains was sufficient to restore inhibition. Interestingly, we observed pseudogenization of the X. poinarii rhabduscin gene cluster via the insertion of a 120 bp element into the isnA promoter. The inhibition of phenoloxidase activity by X. poinarii culture supernatants was restored by expression of the X. poinarii rhabduscin cluster under the control of an inducible Ptet promoter, consistent with recent pseudogenization. This study paves the way for advances in our understanding of the virulence of several entomopathogenic bacteria in non-model insects, such as the new invasive S. frugiperda species in Africa.
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Affiliation(s)
| | - Anne Lanois
- DGIMI, INRA, Université de Montpellier, Montpellier, France
| | - Sylvie Pagès
- DGIMI, INRA, Université de Montpellier, Montpellier, France
| | - Bernard Duvic
- DGIMI, INRA, Université de Montpellier, Montpellier, France
| | - Sophie Gaudriault
- DGIMI, INRA, Université de Montpellier, Montpellier, France
- * E-mail: (MENV); (SG)
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13
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Nematobacterial Complexes and Insect Hosts: Different Weapons for the Same War. INSECTS 2018; 9:insects9030117. [PMID: 30208626 PMCID: PMC6164499 DOI: 10.3390/insects9030117] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 08/22/2018] [Accepted: 09/06/2018] [Indexed: 12/12/2022]
Abstract
Entomopathogenic nematodes (EPNs) are widely used as biological control agents against insect pests, the efficacy of these organisms strongly depends on the balance between the parasitic strategies and the immune response of the host. This review summarizes roles and relationships between insect hosts and two well-known EPN species, Steinernema feltiae and Steinernema carpocapsae and outlines the main mechanisms of immune recognition and defense of insects. Analyzing information and findings about these EPNs, it is clear that these two species use shared immunosuppression strategies, mainly mediated by their symbiotic bacteria, but there are differences in both the mechanism of evasion and interference of the two nematodes with the insect host immune pathways. Based on published data, S. feltiae takes advantage of the cross reaction between its body surface and some host functional proteins, to inhibit defensive processes; otherwise, secretion/excretion products from S. carpocapsae seem to be the main nematode components responsible for the host immunosuppression.
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14
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Sajnaga E, Kazimierczak W, Skowronek M, Lis M, Skrzypek T, Waśko A. Steinernema poinari (Nematoda: Steinernematidae): a new symbiotic host of entomopathogenic bacteria Xenorhabdus bovienii. Arch Microbiol 2018; 200:1307-1316. [PMID: 29946739 PMCID: PMC6182613 DOI: 10.1007/s00203-018-1544-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 06/08/2018] [Accepted: 06/19/2018] [Indexed: 12/20/2022]
Abstract
Three strains of symbiotic bacteria were isolated from an entomopathogenic nematode Steinernema poinari retrieved from soil in eastern Poland. Using 16S rDNA, recA, gltX, gyrB, and dnaN gene sequences for phylogenetic analysis, these strains were shown to belong to the species Xenorhabdus bovienii. The nucleotide identity between the studied S. poinari microsymbionts and other X. bovienii strains calculated for 16S rDNA and concatenated sequences of four protein-coding genes was 98.7-100% and 97.9-99.5%, respectively. The phenotypic properties of the isolates also supported their close phylogenetic relationship with X. bovienii. All three tested X. bovienii strains of different Steinernema clade origin supported the recovery of infective juveniles and subsequent development of the nematode population. However, the colonization degree of new infective juvenile generations was significantly affected by the bacterial host donor/recipient. The colonization degree of infective juveniles reared on bacterial symbionts deriving from a non-cognate clade of nematodes was extremely low, but proved the possible host-switching between non-related Steinernema species.
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Affiliation(s)
- Ewa Sajnaga
- Laboratory of Biocontrol, Application and Production of EPN, Faculty of Biotechnology and Environmental Sciences, Centre for Interdisciplinary Research, John Paul II Catholic University of Lublin, Konstantynów 1J, 20-708, Lublin, Poland.
| | - Waldemar Kazimierczak
- Laboratory of Biocontrol, Application and Production of EPN, Faculty of Biotechnology and Environmental Sciences, Centre for Interdisciplinary Research, John Paul II Catholic University of Lublin, Konstantynów 1J, 20-708, Lublin, Poland
| | - Marcin Skowronek
- Laboratory of Biocontrol, Application and Production of EPN, Faculty of Biotechnology and Environmental Sciences, Centre for Interdisciplinary Research, John Paul II Catholic University of Lublin, Konstantynów 1J, 20-708, Lublin, Poland
| | - Magdalena Lis
- Laboratory of Biocontrol, Application and Production of EPN, Faculty of Biotechnology and Environmental Sciences, Centre for Interdisciplinary Research, John Paul II Catholic University of Lublin, Konstantynów 1J, 20-708, Lublin, Poland
| | - Tomasz Skrzypek
- Laboratory of Confocal and Electron Microscopy, Faculty of Biotechnology and Environmental Sciences, Centre for Interdisciplinary Research, John Paul II Catholic University of Lublin, Konstantynów 1J, 20-708, Lublin, Poland
| | - Adam Waśko
- Department of Biotechnology, Microbiology and Human Nutrition, University of Life Sciences in Lublin, Skromna 8, 20-704, Lublin, Poland
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15
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McQuade R, Stock SP. Secretion Systems and Secreted Proteins in Gram-Negative Entomopathogenic Bacteria: Their Roles in Insect Virulence and Beyond. INSECTS 2018; 9:insects9020068. [PMID: 29921761 PMCID: PMC6023292 DOI: 10.3390/insects9020068] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 06/11/2018] [Accepted: 06/13/2018] [Indexed: 12/12/2022]
Abstract
Many Gram-negative bacteria have evolved insect pathogenic lifestyles. In all cases, the ability to cause disease in insects involves specific bacterial proteins exported either to the surface, the extracellular environment, or the cytoplasm of the host cell. They also have several distinct mechanisms for secreting such proteins. In this review, we summarize the major protein secretion systems and discuss examples of secreted proteins that contribute to the virulence of a variety of Gram-negative entomopathogenic bacteria, including Photorhabdus, Xenorhabdus, Serratia, Yersinia, and Pseudomonas species. We also briefly summarize two classes of exported protein complexes, the PVC-like elements, and the Tc toxin complexes that were first described in entomopathogenic bacteria.
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Affiliation(s)
- Rebecca McQuade
- Center for Insect Science, University of Arizona, 1007 E. Lowell Street, Tucson, AZ 85721, USA.
| | - S Patricia Stock
- Department of Entomology and School of Animal and Comparative Biomedical Sciences, University of Arizona, 1140 E. South Campus Dr., Tucson, AZ 85721, USA.
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16
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Lucas J, Goetsch M, Fischer M, Forst S. Characterization of the pixB gene in Xenorhabdus nematophila and discovery of a new gene family. MICROBIOLOGY-SGM 2018; 164:495-508. [PMID: 29498622 DOI: 10.1099/mic.0.000626] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Xenorhabdus nematophila are Gram-negative bacteria that engage in mutualistic associations with entomopathogenic nematodes. To reproduce, the nematodes invade insects and release X. nematophila into the haemolymph where it functions as an insect pathogen. In complex medium, X. nematophila cells produce two distinct types of intracellular crystalline inclusions, one composed of the methionine-rich PixA protein and the other composed of the PixB protein. Here we show that PixB crystalline inclusions were neither apparent in X. nematophila cells grown in medium that mimics insect haemolymph (Grace's medium) nor in cells grown directly in the insect haemocoel. The identified pixB gene was regulated by a conserved σ70 promoter while the pixA promoter was less well conserved. Expression of pixA and pixB under biological conditions was analysed using GFP promoter reporters. Microplate fluorescence detection and flow cytometry analyses revealed that pixB was expressed at high levels in Grace's medium and in insect haemolymph and at lower levels in complex medium, while pixA was expressed at lower levels under all conditions. Although pixB was highly expressed in Grace's medium, PixB crystalline inclusions were not present, suggesting that under biological conditions PixB production may be controlled post-transcriptionally. Although a pixB-minus strain was constructed, the function of PixB remains unresolved. The pixB gene was present in few Xenorhabdus species and pixB-type genes were identified in some Proteobacteria and Gram-positive species, while pixA was only present in Xenorhabdus species. Two conserved sequences were identified in PixB-type proteins that characterize this previously unrecognized gene family.
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Affiliation(s)
- John Lucas
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, USA
| | - Mary Goetsch
- Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Matt Fischer
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Steven Forst
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, USA
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