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Kgosiemang JL, Ramakuwela T, Figlan S, Cochrane N. Antifungal Effect of Metabolites from Bacterial Symbionts of Entomopathogenic Nematodes on Fusarium Head Blight of Wheat. J Fungi (Basel) 2024; 10:148. [PMID: 38392820 PMCID: PMC10890388 DOI: 10.3390/jof10020148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/05/2024] [Accepted: 02/07/2024] [Indexed: 02/24/2024] Open
Abstract
Fungal diseases such as Fusarium head blight (FHB) are significant biotic stressors, negatively affecting wheat production and quality. This study explored the antifungal activity of the metabolites produced by the bacterial symbionts of entomopathogenic nematodes (EPNs) against FHB-causing Fusarium sp. Fusarium graminearum. To achieve this, the symbiotic bacteria of nine EPN isolates from the EPN collection at the Agricultural Research Council-Small Grains (ARC-SG) were isolated from the cadavers of Galleria mellonella (Lepidoptera: Pyralidae) larvae after infection with EPNs. Broth cultures (crude) and their supernatants (filtered and autoclaved) of each bacterial isolate were used as bacterial metabolite treatments to test their inhibitory effect on the mycelial growth and spore germination of F. graminearum. Mycelial growth inhibition rates varied among both bacterial isolates and treatments. Crude metabolite treatments proved to be more effective than filtered and autoclaved metabolite treatments, with an overall inhibition rate of 75.25% compared to 23.93% and 13.32%, respectively. From the crude metabolite treatments, the Xenorhabdus khoisanae SGI 197 bacterial isolate from Steinernema beitlechemi SGI 197 had the highest mean inhibition rate of 96.25%, followed by Photorhabdus luminescens SGI 170 bacteria isolated from Heterorhabditis bacteriophora SGI 170 with a 95.79% mean inhibition rate. The filtered metabolite treatments of all bacterial isolates were tested for their inhibitory activity against Fusarium graminearum spore germination. Mean spore germination inhibition rates from Xenorhabdus spp. bacterial isolates were higher (83.91 to 96.29%) than those from Photorhabdus spp. (6.05 to 14.74%). The results obtained from this study suggest that EPN symbiotic bacterial metabolites have potential use as biological control agents of FHB. Although field efficacy against FHB was not studied, the significant inhibition of mycelial growth and spore germination suggest that the application of these metabolites at the flowering stage may provide protection to plants against infection with or spread of F. graminearum. These metabolites have the potential to be employed as part of integrated pest management (IPM) to inhibit/delay conidia germination until the anthesis (flowering stage) of wheat seedlings has passed.
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Affiliation(s)
- Julius Leumo Kgosiemang
- Agricultural Research Council-Small Grains, Bethlehem 9701, South Africa
- Department of Agriculture and Animal Health, University of South Africa, Florida 1710, South Africa
| | - Tshimangadzo Ramakuwela
- Agricultural Research Council-Small Grains, Bethlehem 9701, South Africa
- Department of Plant and Soil Sciences, University of Pretoria, Hatfield 0028, South Africa
| | - Sandiswa Figlan
- Department of Agriculture and Animal Health, University of South Africa, Florida 1710, South Africa
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Jin G, Kim IH, Kim Y. The Lrp transcriptional factor of an entomopathogenic bacterium, Xenorhabdus hominickii, activates non-ribosomal peptide synthetases to suppress insect immunity. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2024; 151:105101. [PMID: 38000489 DOI: 10.1016/j.dci.2023.105101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 11/11/2023] [Accepted: 11/17/2023] [Indexed: 11/26/2023]
Abstract
Two bacterial genera, Xenorhabdus and Photorhabdus, are mutually symbiotic to the entomopathogenic nematodes, Steinernema and Heterorhabditis, respectively. The infective juveniles deliver the symbiotic bacteria to the hemocoel of target insects, in which the bacteria proliferate and help the development of the host nematode. The successful parasitism of the nematode-bacterial complex depends on host immunosuppression by the bacteria via their secondary metabolites. Leucine-responsive regulatory protein (Lrp) is a global bacterial transcriptional factor that plays a crucial role in parasitism. However, its regulatory targets to suppress insect immunity are not clearly understood. This study investigated the bacterial genes regulated by Lrp and the subsequent production of secondary metabolites in Xenorhabdus hominickii. Lrp expression occurred at the early infection stage of the bacteria in a target insect, Spodoptera exigua. A preliminary in silico screening indicated that 3.7% genes among 4075 predicted genes encoded in X. hominickii had the Lrp-response element on their promoters, including two non-ribosomal peptide synthetases (NRPSs). Eight NRPS (NRPS1-NRPS8) genes were predicted in the bacterial genome, in which six NRPS (NRPS3-NRPS8) expressions were positively correlated with Lrp expression in the infected larvae of S. exigua. Exchange of the Lrp promoter with an inducible promoter altered the production of the secondary metabolites and the NRPS expression levels. The immunosuppressive activities of X. hominickii were dependent on the Lrp expression level. The metabolites produced by Lrp expression included the eicosanoid-biosynthesis inhibitors and hemolytic factors. A cyclic dipeptide (=cPF) was produced by the bacteria at high Lrp expression and inhibited the phospholipase A2 activity of S. exigua in a competitive inhibitory manner. These results suggest that Lrp is a global transcriptional factor of X. hominickii and plays a crucial role in insect immunosuppression by modulating NRPS expression.
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Affiliation(s)
- Gahyeon Jin
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea
| | - Il-Hwan Kim
- Korea Research Institute of Standards and Science, Daejeon, 34113, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea.
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3
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Global analysis of biosynthetic gene clusters reveals conserved and unique natural products in entomopathogenic nematode-symbiotic bacteria. Nat Chem 2022; 14:701-712. [PMID: 35469007 PMCID: PMC9177418 DOI: 10.1038/s41557-022-00923-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 02/24/2022] [Indexed: 12/27/2022]
Abstract
Microorganisms contribute to the biology and physiology of eukaryotic hosts and affect other organisms through natural products. Xenorhabdus and Photorhabdus (XP) living in mutualistic symbiosis with entomopathogenic nematodes generate natural products to mediate bacteria–nematode–insect interactions. However, a lack of systematic analysis of the XP biosynthetic gene clusters (BGCs) has limited the understanding of how natural products affect interactions between the organisms. Here we combine pangenome and sequence similarity networks to analyse BGCs from 45 XP strains that cover all sequenced strains in our collection and represent almost all XP taxonomy. The identified 1,000 BGCs belong to 176 families. The most conserved families are denoted by 11 BGC classes. We homologously (over)express the ubiquitous and unique BGCs and identify compounds featuring unusual architectures. The bioactivity evaluation demonstrates that the prevalent compounds are eukaryotic proteasome inhibitors, virulence factors against insects, metallophores and insect immunosuppressants. These findings explain the functional basis of bacterial natural products in this tripartite relationship. ![]()
Entomopathogenic nematodes carrying Xenorhabdus and Photorhabdus bacteria prey on insect larvae in the soil. Now, a comprehensive analysis of the bacterial genome has revealed ubiquitous and unique families of biosynthetic gene clusters. Evaluation of the bioactivity of the natural products expressed by the most prevalent cluster families explains the functional basis of bacterial natural products involved in bacteria–nematode–insect interactions.
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Fodor A, Gualtieri M, Zeller M, Tarasco E, Klein MG, Fodor AM, Haynes L, Lengyel K, Forst SA, Furgani GM, Karaffa L, Vellai T. Type Strains of Entomopathogenic Nematode-Symbiotic Bacterium Species, Xenorhabdus szentirmaii (EMC) and X. budapestensis (EMA), Are Exceptional Sources of Non-Ribosomal Templated, Large-Target-Spectral, Thermotolerant-Antimicrobial Peptides (by Both), and Iodinin (by EMC). Pathogens 2022; 11:pathogens11030342. [PMID: 35335666 PMCID: PMC8950435 DOI: 10.3390/pathogens11030342] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/18/2022] [Accepted: 02/23/2022] [Indexed: 01/26/2023] Open
Abstract
Antimicrobial multidrug resistance (MDR) is a global challenge, not only for public health, but also for sustainable agriculture. Antibiotics used in humans should be ruled out for use in veterinary or agricultural settings. Applying antimicrobial peptide (AMP) molecules, produced by soil-born organisms for protecting (soil-born) plants, seems a preferable alternative. The natural role of peptide-antimicrobials, produced by the prokaryotic partner of entomopathogenic-nematode/bacterium (EPN/EPB) symbiotic associations, is to sustain monoxenic conditions for the EPB in the gut of the semi-anabiotic infective dauer juvenile (IJ) EPN. They keep pathobiome conditions balanced for the EPN/EPB complex in polyxenic (soil, vanquished insect cadaver) niches. Xenorhabdus szentirmaii DSM16338(T) (EMC), and X. budapestensis DSM16342(T) (EMA), are the respective natural symbionts of EPN species Steinernema rarum and S. bicornutum. We identified and characterized both of these 15 years ago. The functional annotation of the draft genome of EMC revealed 71 genes encoding non-ribosomal peptide synthases, and polyketide synthases. The large spatial Xenorhabdus AMP (fabclavine), was discovered in EMA, and its biosynthetic pathway in EMC. The AMPs produced by EMA and EMC are promising candidates for controlling MDR prokaryotic and eukaryotic pathogens (bacteria, oomycetes, fungi, protozoa). EMC releases large quantity of iodinin (1,6-dihydroxyphenazine 5,10-dioxide) in a water-soluble form into the media, where it condenses to form spectacular water-insoluble, macroscopic crystals. This review evaluates the scientific impact of international research on EMA and EMC.
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Affiliation(s)
- András Fodor
- Department of Genetics, Eötvös University, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary; (A.M.F.); (K.L.); or (G.M.F.); or (T.V.)
- Department of Genetics, University of Szeged, Középfasor 52, H-6726 Szeged, Hungary
- Correspondence: ; Tel.: +36-(30)-490-9294
| | - Maxime Gualtieri
- Nosopharm, 110 Allée Charles Babbage, Espace Innovation 2, 30000 Nîmes, France;
| | - Matthias Zeller
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47906, USA;
| | - Eustachio Tarasco
- Department of Soil, Plant and Food Sciences, University of Bari “Aldo Moro”, Via Amendola 165/A, 70126 Bari, Italy;
- Institute for Sustainable Plant Protection of CNR, Via Amendola 122/D, 70126 Bari, Italy
| | - Michael G. Klein
- USDA-ARS & Department of Entomology, The Ohio State University, 13416 Claremont Ave, Cleveland, OH 44130, USA;
| | - Andrea M. Fodor
- Department of Genetics, Eötvös University, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary; (A.M.F.); (K.L.); or (G.M.F.); or (T.V.)
| | - Leroy Haynes
- Department of Chemistry, The College of Wooster, Wooster, OH 44691, USA;
| | - Katalin Lengyel
- Department of Genetics, Eötvös University, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary; (A.M.F.); (K.L.); or (G.M.F.); or (T.V.)
- National Institute of Pharmacy and Nutrition (NIPN), Zrinyi utca 3, H-1051 Budapest, Hungary
| | - Steven A. Forst
- Department of Biological Sciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201, USA;
| | - Ghazala M. Furgani
- Department of Genetics, Eötvös University, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary; (A.M.F.); (K.L.); or (G.M.F.); or (T.V.)
- Department of Plant Protection, Faculty of Agriculture, University of Tripoli, Tripoli P.O. Box 13793, Libya
| | - Levente Karaffa
- Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Egyetem Tér 1, H-4032 Debrecen, Hungary;
- Institute of Metagenomics, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary
| | - Tibor Vellai
- Department of Genetics, Eötvös University, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary; (A.M.F.); (K.L.); or (G.M.F.); or (T.V.)
- MTA-ELTE Genetics Research Group, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary
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Selective Toxicity of Secondary Metabolites from the Entomopathogenic Bacterium Photorhabdus luminescens sonorensis against Selected Plant Parasitic Nematodes of the Tylenchina Suborder. Microbiol Spectr 2022; 10:e0257721. [PMID: 35138171 PMCID: PMC8826726 DOI: 10.1128/spectrum.02577-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Entomopathogenic Photorhabdus bacteria (Enterobacteriaceae: Gamma-proteobacteria), the natural symbionts of Heterorhabditis nematodes, are a rich source for the discovery of biologically active secondary metabolites (SMs). This study describes the isolation of three nematicidal SMs from in vitro culture supernatants of the Arizona-native Photorhabdus luminescenssonorensis strain Caborca by bioactivity-guided fractionation. Nuclear magnetic resonance spectroscopy and comparison to authentic synthetic standards identified these bioactive metabolites as trans-cinnamic acid (t-CA), (4E)-5-phenylpent-4-enoic acid (PPA), and indole. PPA and t-CA displayed potent, concentration-dependent nematicidal activities against the root-knot nematode (Meloidogyne incognita) and the citrus nematode (Tylenchulus semipenetrans), two economically and globally important plant parasitic nematodes (PPNs) that are ubiquitous in the United States. Southwest. Indole showed potent, concentration-dependent nematistatic activity by inducing the temporary rigid paralysis of the same targeted nematodes. While paralysis was persistent in the presence of indole, the nematodes recovered upon removal of the compound. All three SMs were found to be selective against the tested PPNs, exerting little effects on non-target species such as the bacteria-feeding nematode Caenorhabditis elegans or the entomopathogenic nematodes Steinernema carpocapsae, Heterorhabditis bacteriophora, and Hymenocallis sonorensis. Moreover, none of these SMs showed cytotoxicity against normal or neoplastic human cells. The combination of t-CA + PPA + indole had a synergistic nematicidal effect on both targeted PPNs. Two-component mixtures prepared from these SMs revealed complex, compound-, and nematode species-dependent interactions. These results justify further investigations into the chemical ecology of Photorhabdus SMs, and recommend t-CA, PPA and indole, alone or in combinations, as lead compounds for the development of selective and environmentally benign nematicides against the tested PPNs. IMPORTANCE Two phenylpropanoid and one alkaloid secondary metabolites were isolated and identified from culture filtrates of Photorhabdus l. sonorensis strain Caborca. The three identified metabolites showed selective nematicidal and/or nematistatic activities against two important plant parasitic nematodes, the root-knot nematode (Meloidogyne incognita) and the citrus nematode (Tylenchulus semipenetrans). The mixture of all three metabolites had a synergistic nematicidal effect on both targeted nematodes, while other combinations showed compound- and nematode-dependent interactions.
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6
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Li JH, Cho W, Hamchand R, Oh J, Crawford JM. A Conserved Nonribosomal Peptide Synthetase in Xenorhabdus bovienii Produces Citrulline-Functionalized Lipopeptides. JOURNAL OF NATURAL PRODUCTS 2021; 84:2692-2699. [PMID: 34581573 PMCID: PMC9970011 DOI: 10.1021/acs.jnatprod.1c00573] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The entomopathogenic bacterium Xenorhabdus bovienii exists in a mutualistic relationship with nematodes of the genus Steinernema. Free-living infective juveniles of Steinernema prey on insect larvae and regurgitate X. bovienii within the hemocoel of a host larva. X. bovienii subsequently produces a complex array of specialized metabolites and effector proteins that kill the insect and regulate various aspects of the trilateral symbiosis. While Xenorhabdus species are rich producers of secondary metabolites, many of their biosynthetic gene clusters remain uncharacterized. Here, we describe a nonribosomal peptide synthetase (NRPS) identified through comparative genomics analysis that is widely conserved in Xenorhabdus species. Heterologous expression of this NRPS gene from X. bovienii in E. coli led to the discovery of a family of lipo-tripeptides that chromatographically appear as pairs, containing either a C-terminal carboxylic acid or carboxamide. Coexpression of the NRPS with the leupeptin protease inhibitor pathway enhanced production, facilitating isolation and characterization efforts. The new lipo-tripeptides were also detected in wild-type X. bovienii cultures. These metabolites, termed bovienimides, share an uncommon C-terminal d-citrulline residue. The NRPS lacked a dedicated chain termination domain, resulting in product diversification and release from the assembly line through reactions with ammonia, water, or exogenous alcohols.
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Affiliation(s)
- Jhe-Hao Li
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
- Institute of Biomolecular Design and Discovery, Yale University, West Haven, Connecticut 06516, United States
| | - Wooyoung Cho
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
- Institute of Biomolecular Design and Discovery, Yale University, West Haven, Connecticut 06516, United States
| | - Randy Hamchand
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
- Institute of Biomolecular Design and Discovery, Yale University, West Haven, Connecticut 06516, United States
| | - Joonseok Oh
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
- Institute of Biomolecular Design and Discovery, Yale University, West Haven, Connecticut 06516, United States
| | - Jason M Crawford
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
- Institute of Biomolecular Design and Discovery, Yale University, West Haven, Connecticut 06516, United States
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut 06536, United States
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7
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Booysen E, Dicks LMT. Does the Future of Antibiotics Lie in Secondary Metabolites Produced by Xenorhabdus spp.? A Review. Probiotics Antimicrob Proteins 2021; 12:1310-1320. [PMID: 32844362 DOI: 10.1007/s12602-020-09688-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The over-prescription of antibiotics for treatment of infections is primarily to blame for the increase in bacterial resistance. Added to the problem is the slow rate at which novel antibiotics are discovered and the many processes that need to be followed to classify antimicrobials safe for medical use. Xenorhabdus spp. of the family Enterobacteriaceae, mutualistically associated with entomopathogenic nematodes of the genus Steinernema, produce a variety of antibacterial peptides, including bacteriocins, depsipeptides, xenocoumacins and PAX (peptide antimicrobial-Xenorhabdus) peptides, plus additional secondary metabolites with antibacterial and antifungal activity. The secondary metabolites of some strains are active against protozoa and a few have anti-carcinogenic properties. It is thus not surprising that nematodes invaded by a single strain of a Xenorhabdus species are not infected by other microorganisms. In this review, the antimicrobial compounds produced by Xenorhabdus spp. are listed and the gene clusters involved in synthesis of these secondary metabolites are discussed. We also review growth conditions required for increased production of antimicrobial compounds.
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Affiliation(s)
- E Booysen
- Department of Microbiology, Stellenbosch University, Stellenbosch, 7600, South Africa
| | - L M T Dicks
- Department of Microbiology, Stellenbosch University, Stellenbosch, 7600, South Africa.
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8
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Mollah MMI, Kim Y. Virulent secondary metabolites of entomopathogenic bacteria genera, Xenorhabdus and Photorhabdus, inhibit phospholipase A 2 to suppress host insect immunity. BMC Microbiol 2020; 20:359. [PMID: 33228536 PMCID: PMC7684946 DOI: 10.1186/s12866-020-02042-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/10/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Xenorhabdus and Photorhabdus are entomopathogenic bacteria that cause septicemia and toxemia in insects. They produce secondary metabolites to induce host immunosuppression. Their metabolite compositions vary among bacterial species. Little is known about the relationship between metabolite compositions and the bacterial pathogenicity. The objective of this study was to compare pathogenicity and production of secondary metabolites of 14 bacterial isolates (species or strains) of Xenorhabdus and Photorhabdus. RESULTS All bacterial isolates exhibited insecticidal activities after hemocoelic injection to Spodoptera exigua (a lepidopteran insect) larvae, with median lethal doses ranging from 168.8 to 641.3 CFU per larva. Bacterial infection also led to immunosuppression by inhibiting eicosanoid biosynthesis. Bacterial culture broth was fractionated into four different organic extracts. All four organic extracts of each bacterial species exhibited insecticidal activities and resulted in immunosuppression. These organic extracts were subjected to GC-MS analysis which predicted 182 compounds, showing differential compositions for 14 bacteria isolates. There were positive correlations between total number of secondary metabolites produced by each bacterial culture broth and its bacterial pathogenicity based on immunosuppression and insecticidal activity. From these correlation results, 70 virulent compounds were selected from secondary metabolites of high virulent bacterial isolates by deducting those of low virulent bacterial isolates. These selected virulent compounds exhibited significant immunosuppressive activities by inhibiting eicosanoid biosynthesis. They also exhibited relatively high insecticidal activities. CONCLUSION Virulence variation between Xenorhabdus and Photorhabdus is determined by their different compositions of secondary metabolites, of which PLA2 inhibitors play a crucial role.
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Affiliation(s)
- Md Mahi Imam Mollah
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea.
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9
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Symbiosis, virulence and natural-product biosynthesis in entomopathogenic bacteria are regulated by a small RNA. Nat Microbiol 2020; 5:1481-1489. [PMID: 33139881 DOI: 10.1038/s41564-020-00797-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 09/16/2020] [Indexed: 01/07/2023]
Abstract
Photorhabdus and Xenorhabdus species have mutualistic associations with nematodes and an entomopathogenic stage1,2 in their life cycles. In both stages, numerous specialized metabolites are produced that have roles in symbiosis and virulence3,4. Although regulators have been implicated in the regulation of these specialized metabolites3,4, how small regulatory RNAs (sRNAs) are involved in this process is not clear. Here, we show that the Hfq-dependent sRNA, ArcZ, is required for specialized metabolite production in Photorhabdus and Xenorhabdus. We discovered that ArcZ directly base-pairs with the mRNA encoding HexA, which represses the expression of specialized metabolite gene clusters. In addition to specialized metabolite genes, we show that the ArcZ regulon affects approximately 15% of all transcripts in Photorhabdus and Xenorhabdus. Thus, the ArcZ sRNA is crucial for specialized metabolite production in Photorhabdus and Xenorhabdus species and could become a useful tool for metabolic engineering and identification of commercially relevant natural products.
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10
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Abstract
Different model systems have, over the years, contributed to our current understanding of the molecular mechanisms underpinning the various types of interaction between bacteria and their animal hosts. The genus
Photorhabdus
comprises Gram-negative insect pathogenic bacteria that are normally found as symbionts that colonize the gut of the infective juvenile stage of soil-dwelling nematodes from the family Heterorhabditis. The nematodes infect susceptible insects and release the bacteria into the insect haemolymph where the bacteria grow, resulting in the death of the insect. At this stage the nematodes feed on the bacterial biomass and, following several rounds of reproduction, the nematodes develop into infective juveniles that leave the insect cadaver in search of new hosts. Therefore
Photorhabdus
has three distinct and obligate roles to play during this life-cycle: (1)
Photorhabdus
must kill the insect host; (2)
Photorhabdus
must be capable of supporting nematode growth and development; and (3)
Photorhabdus
must be able to colonize the gut of the next generation of infective juveniles before they leave the insect cadaver. In this review I will discuss how genetic analysis has identified key genes involved in mediating, and regulating, the interaction between
Photorhabdus
and each of its invertebrate hosts. These studies have resulted in the characterization of several new families of toxins and a novel inter-kingdom signalling molecule and have also uncovered an important role for phase variation in the regulation of these different roles.
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Affiliation(s)
- David J Clarke
- School of Microbiology and APC Microbiome Ireland, University College Cork, Cork, Ireland
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11
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Wang G, Zhao Z, Ke J, Engel Y, Shi YM, Robinson D, Bingol K, Zhang Z, Bowen B, Louie K, Wang B, Evans R, Miyamoto Y, Cheng K, Kosina S, De Raad M, Silva L, Luhrs A, Lubbe A, Hoyt DW, Francavilla C, Otani H, Deutsch S, Washton NM, Rubin EM, Mouncey NJ, Visel A, Northen T, Cheng JF, Bode HB, Yoshikuni Y. CRAGE enables rapid activation of biosynthetic gene clusters in undomesticated bacteria. Nat Microbiol 2019; 4:2498-2510. [PMID: 31611640 DOI: 10.1038/s41564-019-0573-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 08/27/2019] [Indexed: 12/11/2022]
Abstract
It is generally believed that exchange of secondary metabolite biosynthetic gene clusters (BGCs) among closely related bacteria is an important driver of BGC evolution and diversification. Applying this idea may help researchers efficiently connect many BGCs to their products and characterize the products' roles in various environments. However, existing genetic tools support only a small fraction of these efforts. Here, we present the development of chassis-independent recombinase-assisted genome engineering (CRAGE), which enables single-step integration of large, complex BGC constructs directly into the chromosomes of diverse bacteria with high accuracy and efficiency. To demonstrate the efficacy of CRAGE, we expressed three known and six previously identified but experimentally elusive non-ribosomal peptide synthetase (NRPS) and NRPS-polyketide synthase (PKS) hybrid BGCs from Photorhabdus luminescens in 25 diverse γ-Proteobacteria species. Successful activation of six BGCs identified 22 products for which diversity and yield were greater when the BGCs were expressed in strains closely related to the native strain than when they were expressed in either native or more distantly related strains. Activation of these BGCs demonstrates the feasibility of exploiting their underlying catalytic activity and plasticity, and provides evidence that systematic approaches based on CRAGE will be useful for discovering and identifying previously uncharacterized metabolites.
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Affiliation(s)
- Gaoyan Wang
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - Zhiying Zhao
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - Jing Ke
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - Yvonne Engel
- Molecular Biotechnology, Department of Biosciences and Buchmann Institute for Molecular Life Sciences, Goethe Universität Frankfurt, Frankfurt am Main, Germany
| | - Yi-Ming Shi
- Molecular Biotechnology, Department of Biosciences and Buchmann Institute for Molecular Life Sciences, Goethe Universität Frankfurt, Frankfurt am Main, Germany
| | - David Robinson
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - Kerem Bingol
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Zheyun Zhang
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - Benjamin Bowen
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Katherine Louie
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - Bing Wang
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - Robert Evans
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - Yu Miyamoto
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - Kelly Cheng
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - Suzanne Kosina
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Markus De Raad
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Leslie Silva
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | | | | | - David W Hoyt
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA
| | | | - Hiroshi Otani
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Samuel Deutsch
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.,Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Nancy M Washton
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Edward M Rubin
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - Nigel J Mouncey
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Axel Visel
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Trent Northen
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jan-Fang Cheng
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Helge B Bode
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA. .,LOEWE Centre for Translational Biodiversity Genomics, Frankfurt, Germany.
| | - Yasuo Yoshikuni
- US Department of Energy Joint Genome Institute, Berkeley, CA, USA. .,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. .,Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. .,Center for Advanced Bioenergy and Bioproducts Innovation, Urbana, IL, USA. .,Global Institution for Collaborative Research and Education, Hokkaido University, Hokkaido, Japan.
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12
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Cambon MC, Parthuisot N, Pagès S, Lanois A, Givaudan A, Ferdy JB. Selection of Bacterial Mutants in Late Infections: When Vector Transmission Trades Off against Growth Advantage in Stationary Phase. mBio 2019; 10:e01437-19. [PMID: 31594811 PMCID: PMC6786866 DOI: 10.1128/mbio.01437-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 09/04/2019] [Indexed: 11/20/2022] Open
Abstract
Bacterial infections are often composed of cells with distinct phenotypes that can be produced by genetic or epigenetic mechanisms. This phenotypic heterogeneity has proved to be important in many pathogens, because it can alter both pathogenicity and transmission. We studied how and why it can emerge during infection in the bacterium Xenorhabdus nematophila, a pathogen that kills insects and multiplies in the cadaver before being transmitted by the soil nematode vector Steinernema carpocapsae We found that phenotypic variants cluster in three groups, one of which is composed of lrp defective mutants. These mutants, together with variants of another group, have in common that they maintain high survival during late stationary phase. This probably explains why they increase in frequency: variants of X. nematophila with a growth advantage in stationary phase (GASP) are under strong positive selection both in prolonged culture and in late infections. We also found that the within-host advantage of these variants seems to trade off against transmission by nematode vectors: the variants that reach the highest load in insects are those that are the least transmitted.IMPORTANCE Pathogens can evolve inside their host, and the importance of this mutation-fueled process is increasingly recognized. A disease outcome may indeed depend in part on pathogen adaptations that emerge during infection. It is therefore important to document these adaptations and the conditions that drive them. In our study, we took advantage of the possibility to monitor within-host evolution in the insect pathogen X. nematophila We demonstrated that selection occurring in aged infection favors lrp defective mutants, because these metabolic mutants benefit from a growth advantage in stationary phase (GASP). We also demonstrated that these mutants have reduced virulence and impaired transmission, modifying the infection outcome. Beyond the specific case of X. nematophila, we propose that metabolic mutants are to be found in other bacterial pathogens that stay for many generations inside their host.
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Affiliation(s)
- Marine C Cambon
- Évolution et Diversité Biologique, CNRS-Université Paul Sabatier, Toulouse, France
- Diversité, Génome et Interactions Microorganismes Insectes, INRA-Université Montpellier, Montpellier, France
| | - Nathalie Parthuisot
- Évolution et Diversité Biologique, CNRS-Université Paul Sabatier, Toulouse, France
| | - Sylvie Pagès
- Diversité, Génome et Interactions Microorganismes Insectes, INRA-Université Montpellier, Montpellier, France
| | - Anne Lanois
- Diversité, Génome et Interactions Microorganismes Insectes, INRA-Université Montpellier, Montpellier, France
| | - Alain Givaudan
- Diversité, Génome et Interactions Microorganismes Insectes, INRA-Université Montpellier, Montpellier, France
| | - Jean-Baptiste Ferdy
- Évolution et Diversité Biologique, CNRS-Université Paul Sabatier, Toulouse, France
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13
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Zhang S, Liu Q, Han Y, Han J, Yan Z, Wang Y, Zhang X. Nematophin, an Antimicrobial Dipeptide Compound From Xenorhabdus nematophila YL001 as a Potent Biopesticide for Rhizoctonia solani Control. Front Microbiol 2019; 10:1765. [PMID: 31440217 PMCID: PMC6693444 DOI: 10.3389/fmicb.2019.01765] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 07/16/2019] [Indexed: 11/13/2022] Open
Abstract
This study was conducted to purify and identify metabolites of antimicrobial activity against phytopathogens from Xenorhabdus nematophila YL001. Three dipeptide compounds were purified from its cell-free cultural broth and identified as (±)-nematophin, cyclo (L-Pro-Gly), and N, N'-dimethyl-cyclo (L-Phe-L-Leu). Nematophin demonstrated a wider antifungal spectrum than the other two compounds. It also exhibited strong inhibitory effects on mycelial growth of Rhizoctonia solani and Phytophthora infestans with EC50 values of 40.00 and 51.25 μg/ml, respectively. Its (S)-configuration structure [(+)-nematophin] was also synthesized and exhibited higher antimicrobial activity than the enantiomeric mixture. The detached leaf assay revealed that nematophin possessed significant preventive and curative efficacy against R. solani on broad bean leaves showing corresponding control efficacies of 93.01 and 94.93% at 1,000 μg/ml, comparable to those of a chemical fungicide (carbendazim) at 500 μg/ml. Additionally, the pot experiments indicated that nematophin could effectively inhibit the disease extension on rice and broad bean plants caused by R. solani. Nematophin also exerted some adverse influences on the sclerotial development of R. solani by dramatically suppressing their formation and maturation at 40.00 μg/ml, as well as their germination at 15.00 μg/ml. Morphological and ultrastructural observations showed that the hyphae of R. solani became twisted, shriveled, and deformed at the growing points after exposure to nematophin at 40.00 μg/ml, and that the subcellular fractions also became abnormal concurrently, especially the mitochondrial structure. These results indicate that nematophin has great potential to be used as a bio-pesticide in agricultural production.
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Affiliation(s)
- Shujing Zhang
- Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Research and Development Center of Biorational Pesticides, College of Plant Protection, Northwest A&F University, Yangling, China
| | - Qi Liu
- Plant Quarantine and Protection Bureau of Zhumadian, Zhumadian, China
| | - Yunfei Han
- Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Research and Development Center of Biorational Pesticides, College of Plant Protection, Northwest A&F University, Yangling, China
| | - Jinghua Han
- Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Research and Development Center of Biorational Pesticides, College of Plant Protection, Northwest A&F University, Yangling, China
| | - Zhiqiang Yan
- Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Research and Development Center of Biorational Pesticides, College of Plant Protection, Northwest A&F University, Yangling, China
| | - Yonghong Wang
- Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Research and Development Center of Biorational Pesticides, College of Plant Protection, Northwest A&F University, Yangling, China
| | - Xing Zhang
- Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Research and Development Center of Biorational Pesticides, College of Plant Protection, Northwest A&F University, Yangling, China
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14
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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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15
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Guo S, Wang Z, Liu B, Gao J, Fang X, Tang Q, Bilal M, Wang Y, Zhang X. Effects of cpxR on the growth characteristics and antibiotic production of Xenorhabdus nematophila. Microb Biotechnol 2019; 12:447-458. [PMID: 30623566 PMCID: PMC6465229 DOI: 10.1111/1751-7915.13362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 09/23/2018] [Accepted: 12/11/2018] [Indexed: 11/28/2022] Open
Abstract
CpxR is a global response regulator that negatively influences the antimicrobial activities of Xenorhabdus nematophila. Herein, the wildtype and ΔcpxR mutant of X. nematophila were cultured in a 5‐l and 70‐l bioreactor. The kinetic analysis showed that ΔcpxR significantly increased the cell biomass and antibiotic activity. The maximum dry cell weight (DCW) and antibiotic activity of ΔcpxR were 20.77 ± 1.56 g L−1 and 492.0 ± 31.2 U ml−1 and increased by 17.28 and 97.33% compared to the wildtype respectively. Xenocoumacin 1 (Xcn1), a major antimicrobial compound, was increased 3.07‐fold, but nematophin was decreased by 48.7%. In 70‐l bioreactor, DCW was increased by 18.97%, while antibiotic activity and Xcn1 were decreased by 27.71% and 11.0% compared to that in 5‐l bioreactor respectively. Notably, pH had remarkable effects on the cell biomass and antibiotic activity of ΔcpxR, where ΔcpxR was sensitive to alkaline pH conditions. The optimal cell growth and antibiotic activity of ΔcpxR occurred at pH 7.0, while Xcn1 was increased 5.45‐ and 3.87‐fold relative to that at pH 5.5 and 8.5 respectively. These findings confirmed that ΔcpxR considerably increased the biomass of X. nematophila at a late stage of fermentation. In addition, ΔcpxR significantly promoted the biosynthesis of Xcns but decreased the production of nematophin.
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Affiliation(s)
- Shuqi Guo
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China.,State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zeyu Wang
- School of Food and Biological Engineering, Shaanxi University of Science & Technology, Weiyang University Campus, Xi 'an Shaanxi, 710021, China
| | - Beiling Liu
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China
| | - Jiangtao Gao
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China
| | - Xiangling Fang
- State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.,School of Agriculture and Environment, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Qian Tang
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China
| | - Muhammad Bilal
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003, China
| | - Yonghong Wang
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China.,Shaanxi Research Center of Biopesticide Engineering and Technology, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China
| | - Xing Zhang
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China.,Shaanxi Research Center of Biopesticide Engineering and Technology, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China
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16
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Dreyer J, Malan AP, Dicks LMT. Bacteria of the Genus Xenorhabdus, a Novel Source of Bioactive Compounds. Front Microbiol 2018; 9:3177. [PMID: 30619229 PMCID: PMC6305712 DOI: 10.3389/fmicb.2018.03177] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 12/07/2018] [Indexed: 12/04/2022] Open
Abstract
The genus Xenorhabdus of the family Enterobacteriaceae, are mutualistically associated with entomopathogenic nematodes of the genus Steinernema. Although most of the associations are species-specific, a specific Xenorhabdus sp. may infect more than one Steinernema sp. During the Xenorhabdus-Steinernema life cycle, insect larvae are infected and killed, while both mutualists produce bioactive compounds. These compounds act synergistically to ensure reproduction and proliferation of the nematodes and bacteria. A single strain of Xenorhabdus may produce a variety of antibacterial and antifungal compounds, some of which are also active against insects, nematodes, protozoa, and cancer cells. Antimicrobial compounds produced by Xenorhabdus spp. have not been researched to the same extent as other soil bacteria and they may hold the answer to novel antibacterial and antifungal compounds. This review summarizes the bioactive secondary metabolites produced by Xenorhabdus spp. and their application in disease control. Gene regulation and increasing the production of a few of these antimicrobial compounds are discussed. Aspects limiting future development of these novel bioactive compounds are also pointed out.
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Affiliation(s)
- Jönike Dreyer
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
| | - Antoinette P. Malan
- Department of Conservation Ecology and Entomology, Stellenbosch University, Stellenbosch, South Africa
| | - Leon M. T. Dicks
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
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17
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Zamora-Lagos MA, Eckstein S, Langer A, Gazanis A, Pfeiffer F, Habermann B, Heermann R. Phenotypic and genomic comparison of Photorhabdus luminescens subsp. laumondii TT01 and a widely used rifampicin-resistant Photorhabdus luminescens laboratory strain. BMC Genomics 2018; 19:854. [PMID: 30497380 PMCID: PMC6267812 DOI: 10.1186/s12864-018-5121-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 09/26/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Photorhabdus luminescens is an enteric bacterium, which lives in mutualistic association with soil nematodes and is highly pathogenic for a broad spectrum of insects. A complete genome sequence for the type strain P. luminescens subsp. laumondii TT01, which was originally isolated in Trinidad and Tobago, has been described earlier. Subsequently, a rifampicin resistant P. luminescens strain has been generated with superior possibilities for experimental characterization. This strain, which is widely used in research, was described as a spontaneous rifampicin resistant mutant of TT01 and is known as TT01-RifR. RESULTS Unexpectedly, upon phenotypic comparison between the rifampicin resistant strain and its presumed parent TT01, major differences were found with respect to bioluminescence, pigmentation, biofilm formation, haemolysis as well as growth. Therefore, we renamed the strain TT01-RifR to DJC. To unravel the genomic basis of the observed differences, we generated a complete genome sequence for strain DJC using the PacBio long read technology. As strain DJC was supposed to be a spontaneous mutant, only few sequence differences were expected. In order to distinguish these from potential sequencing errors in the published TT01 genome, we re-sequenced a derivative of strain TT01 in parallel, also using the PacBio technology. The two TT01 genomes differed at only 30 positions. In contrast, the genome of strain DJC varied extensively from TT01, showing 13,000 point mutations, 330 frameshifts, and 220 strain-specific regions with a total length of more than 300 kb in each of the compared genomes. CONCLUSIONS According to the major phenotypic and genotypic differences, the rifampicin resistant P. luminescens strain, now named strain DJC, has to be considered as an independent isolate rather than a derivative of strain TT01. Strains TT01 and DJC both belong to P. luminescens subsp. laumondii.
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Affiliation(s)
- Maria-Antonia Zamora-Lagos
- Computational Biology Group, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Simone Eckstein
- Biozentrum, Bereich Mikrobiologie, Ludwig-Maximilians-Universität München, Großhaderner Str. 2-4, 82152, Martinsried, Germany
| | - Angela Langer
- Biozentrum, Bereich Mikrobiologie, Ludwig-Maximilians-Universität München, Großhaderner Str. 2-4, 82152, Martinsried, Germany
| | - Athanasios Gazanis
- Biozentrum, Bereich Mikrobiologie, Ludwig-Maximilians-Universität München, Großhaderner Str. 2-4, 82152, Martinsried, Germany
| | - Friedhelm Pfeiffer
- Computational Biology Group, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Bianca Habermann
- Computational Biology Group, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany. .,CNRS UMR 7288, Computational Biology Group, Developmental Biology Institute of Marseille (IBDM), Aix Marseille Université, 13009, Marseille, France.
| | - Ralf Heermann
- Biozentrum, Bereich Mikrobiologie, Ludwig-Maximilians-Universität München, Großhaderner Str. 2-4, 82152, Martinsried, Germany.
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18
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Zhang S, Fang X, Tang Q, Ge J, Wang Y, Zhang X. CpxR negatively regulates the production of xenocoumacin 1, a dihydroisocoumarin derivative produced by Xenorhabdus nematophila. Microbiologyopen 2018; 8:e00674. [PMID: 29888873 PMCID: PMC6391269 DOI: 10.1002/mbo3.674] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 05/07/2018] [Accepted: 05/19/2018] [Indexed: 11/10/2022] Open
Abstract
Xenocoumacin 1 (Xcn1), a major antimicrobial compound produced by Xenorhabdus nematophila, has great potential for use in agricultural productions. In this study, we evaluated the effects of CpxR, a global response regulator associated with the mutualism and pathogenesis of X. nematophila, on the antimicrobial activity and Xcn1 production. The mutation of cpxR could promote the production of Xcn1 significantly with its level in ΔcpxR mutant being 3.07 times higher than that in the wild type. Additionally, the expression levels of xcnA‐L genes, which are responsible for the production of Xcn1, were increased in ΔcpxR mutant while the expression levels of xcnMN, which are required for the conversion of Xcn1 into Xcn2 was reduced. Noticeably, Xcn2 was also enhanced on account of the conversion of excessive Xcn1 in spite of low expression levels of xcnM and xcnN in ΔcpxR mutant. The transcriptional levels of ompR and lrp, encoding the global response regulators OmpR and Lrp which negatively and positively regulate the production of Xcn1 were concurrently decreased and increased, respectively. Correspondingly, ΔcpxR mutant also exhibited increased antimicrobial activities in vitro and in vivo. Together, these findings suggest that CpxR negatively regulates xcnA‐L genes expression while positively regulating xcnMN expression in X. nematophila YL001, which led to a high yield of Xcn1 in ΔcpxR mutant.
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Affiliation(s)
- Shujing Zhang
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A &F University, Yangling, Shaanxi, China
| | - Xiangling Fang
- State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China.,School of Agriculture and Environment, Faculty of Science, The University of Western Australia, Crawley, Western Australia, Australia
| | - Qian Tang
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A &F University, Yangling, Shaanxi, China
| | - Jing Ge
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A &F University, Yangling, Shaanxi, China
| | - Yonghong Wang
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A &F University, Yangling, Shaanxi, China
| | - Xing Zhang
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A &F University, Yangling, Shaanxi, China
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19
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Ahmed S, Kim Y. Differential immunosuppression by inhibiting PLA 2 affects virulence of Xenorhabdus hominickii and Photorhabdus temperata temperata. J Invertebr Pathol 2018; 157:136-146. [PMID: 29802883 DOI: 10.1016/j.jip.2018.05.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 05/19/2018] [Accepted: 05/22/2018] [Indexed: 11/17/2022]
Abstract
Immunity negatively influences bacterial pathogenicity. Eicosanoids mediate both cellular and humoral immune responses in insects. This study tested a hypothesis that differential bacterial virulence of Xenorhabdus/Photorhabdus is dependent on their inhibitory activity against phospholipase A2 (PLA2) activity. P. temperata subsp. temperata ('Ptt') was more than 40 times more potent than X. hominickii ('Xh'). Although both bacteria suppressed cellular immune responses, Ptt infection suppressed hemocyte nodule formation much more than Xh infection. Their differential immunosuppression appeared to be induced by their secondary metabolites because organic extracts of Ptt-cultured broth exhibited higher inhibitory activities against cellular immune responses than Xn-cultured broth extracts. Humoral immune responses were analyzed by measuring expression levels of 11 antimicrobial peptide (AMP) genes. Among inducible AMPs in hemocytes and fat body, higher number and more kinds of AMPs exhibited lower expression levels in Ptt infection than those in Xh infection. Suppressed immune responses induced by Ptt or Xh infection were significantly rescued by the addition of a catalytic product of PLA2, suggesting that PLA2 was a common inhibitory target. In fact, Ptt infection inhibited PLA2 activity more strongly than Xh infection. RNA interference of a PLA2 gene decreased its expression and significantly increased bacterial virulence. Moreover, addition of PLA2 inhibitor to Xh infection enhanced its virulence, similar to virulence level of Ptt infection. These results suggest that variation in Xenorhabdus/Photorhabdus bacterial virulence can be explained by their differential inhibitory activities against host insect PLA2.
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Affiliation(s)
- Shabbir Ahmed
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea.
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20
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Heinrich AK, Hirschmann M, Neubacher N, Bode HB. LuxS-dependent AI-2 production is not involved in global regulation of natural product biosynthesis in Photorhabdus and Xenorhabdus. PeerJ 2017; 5:e3471. [PMID: 28663937 PMCID: PMC5488855 DOI: 10.7717/peerj.3471] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 05/26/2017] [Indexed: 01/06/2023] Open
Abstract
The Gram-negative bacteria Photorhabdus and Xenorhabdus are known to produce a variety of different natural products (NP). These compounds play different roles since the bacteria live in symbiosis with nematodes and are pathogenic to insect larvae in the soil. Thus, a fine tuned regulatory system controlling NP biosynthesis is indispensable. Global regulators such as Hfq, Lrp, LeuO and HexA have been shown to influence NP production of Photorhabdus and Xenorhabdus. Additionally, photopyrones as quorum sensing (QS) signals were demonstrated to be involved in the regulation of NP production in Photorhabdus. In this study, we investigated the role of another possible QS signal, autoinducer-2 (AI-2), in regulation of NP production. The AI-2 synthase (LuxS) is widely distributed within the bacterial kingdom and has a dual role as a part of the activated methyl cycle pathway, as well as being responsible for AI-2 precursor production. We deleted luxS in three different entomopathogenic bacteria and compared NP levels in the mutant strains to the wild type (WT) but observed no difference to the WT strains. Furthermore, the absence of the small regulatory RNA micA, which is encoded directly upstream of luxS, did not influence NP levels. Phenotypic differences between the P. luminescens luxS deletion mutant and an earlier described luxS deficient strain of P. luminescens suggested that two phenotypically different strains have evolved in different laboratories.
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Affiliation(s)
- Antje K. Heinrich
- Fachbereich Biowissenschaften, Merck Stiftungsprofessur für Molekulare Biotechnologie, Goethe-Universität Frankfurt, Frankfurt am Main, Germany
| | - Merle Hirschmann
- Fachbereich Biowissenschaften, Merck Stiftungsprofessur für Molekulare Biotechnologie, Goethe-Universität Frankfurt, Frankfurt am Main, Germany
| | - Nick Neubacher
- Fachbereich Biowissenschaften, Merck Stiftungsprofessur für Molekulare Biotechnologie, Goethe-Universität Frankfurt, Frankfurt am Main, Germany
| | - Helge B. Bode
- Fachbereich Biowissenschaften, Merck Stiftungsprofessur für Molekulare Biotechnologie, Goethe-Universität Frankfurt, Frankfurt am Main, Germany
- Buchmann Institute for Molecular Life Sciences, Goethe-Universität Frankfurt, Frankfurt am Main, Germany
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High Levels of the Xenorhabdus nematophila Transcription Factor Lrp Promote Mutualism with the Steinernema carpocapsae Nematode Host. Appl Environ Microbiol 2017; 83:AEM.00276-17. [PMID: 28389546 DOI: 10.1128/aem.00276-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/04/2017] [Indexed: 11/20/2022] Open
Abstract
Xenorhabdus nematophila bacteria are mutualistic symbionts of Steinernema carpocapsae nematodes and pathogens of insects. The X. nematophila global regulator Lrp controls the expression of many genes involved in both mutualism and pathogenic activities, suggesting a role in the transition between the two host organisms. We previously reported that natural populations of X. nematophila exhibit various levels of Lrp expression and that cells expressing relatively low levels of Lrp are optimized for virulence in the insect Manduca sexta The adaptive advantage of the high-Lrp-expressing state was not established. Here we used strains engineered to express constitutively high or low levels of Lrp to test the model in which high-Lrp-expressing cells are adapted for mutualistic activities with the nematode host. We demonstrate that high-Lrp cells form more robust biofilms in laboratory media than do low-Lrp cells, which may reflect adherence to host tissues. Also, our data showed that nematodes cultivated with high-Lrp strains are more frequently colonized than are those associated with low-Lrp strains. Taken together, these data support the idea that high-Lrp cells have an advantage in tissue adherence and colonization initiation. Furthermore, our data show that high-Lrp-expressing strains better support nematode reproduction than do their low-Lrp counterparts under both in vitro and in vivo conditions. Our data indicate that heterogeneity of Lrp expression in X. nematophila populations provides diverse cell populations adapted to both pathogenic (low-Lrp) and mutualistic (high-Lrp) states.IMPORTANCE Host-associated bacteria experience fluctuating conditions during both residence within an individual host and transmission between hosts. For bacteria that engage in evolutionarily stable, long-term relationships with particular hosts, these fluctuations provide selective pressure for the emergence of adaptive regulatory mechanisms. Here we present evidence that the bacterium Xenorhabdus nematophila uses various levels of the transcription factor Lrp to optimize its association with its two animal hosts, nematodes and insects, with which it behaves as a mutualist and a pathogen, respectively. Building on our previous finding that relatively low cellular levels of Lrp are optimal for pathogenesis, we demonstrate that, conversely, high levels of Lrp promote mutualistic activities with the Steinernema carpocapsae nematode host. These data suggest that X. nematophila has evolved to utilize phenotypic variation between high- and low-Lrp-expression states to optimize its alternating behaviors as a mutualist and a pathogen.
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Langer A, Moldovan A, Harmath C, Joyce SA, Clarke DJ, Heermann R. HexA is a versatile regulator involved in the control of phenotypic heterogeneity of Photorhabdus luminescens. PLoS One 2017; 12:e0176535. [PMID: 28448559 PMCID: PMC5407808 DOI: 10.1371/journal.pone.0176535] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 04/12/2017] [Indexed: 12/04/2022] Open
Abstract
Phenotypic heterogeneity in microbial communities enables genetically identical organisms to behave differently even under the same environmental conditions. Photorhabdus luminescens, a bioluminescent Gram-negative bacterium, contains a complex life cycle, which involves a symbiotic interaction with nematodes as well as a pathogenic association with insect larvae. P. luminescens exists in two distinct phenotypic cell types, designated as the primary (1°) and secondary (2°) cells. The 1° cells are bioluminescent, pigmented and can support nematode growth and development. Individual 1° cells undergo phenotypic switching after prolonged cultivation and convert to 2° cells, which lack the 1° specific phenotypes. The LysR-type regulator HexA has been described as major regulator of this switching process. Here we show that HexA controls phenotypic heterogeneity in a versatile way, directly and indirectly. Expression of hexA is enhanced in 2° cells, and the corresponding regulator inhibits 1° specific traits in 2° cells. HexA does not directly affect bioluminescence, a predominant 1° specific phenotype. Since the respective luxCDABE operon is repressed at the post-transcriptional level and transcriptional levels of the RNA chaperone gene hfq are also enhanced in 2° cells, small regulatory RNAs are presumably involved that are under control of HexA. Another phenotypic trait that is specific for 1° cells is quorum sensing mediated cell clumping. The corresponding pcfABCDEF operon could be identified as the first direct target of HexA, since the regulator binds to the pcfA promoter region and thereby blocks expression of the target operon. In summary, our data show that HexA fulfills the task as repressor of 1° specific features in 2° cells in a versatile way and gives first insights into the complexity of regulating phenotypic heterogeneity in Photorhabdus bacteria.
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Affiliation(s)
- Angela Langer
- Bereich Mikrobiologie, Biozentrum Martinsried, Ludwig-Maximilians-Universität München, München, Germany
| | - Adriana Moldovan
- Bereich Mikrobiologie, Biozentrum Martinsried, Ludwig-Maximilians-Universität München, München, Germany
| | - Christian Harmath
- Bereich Mikrobiologie, Biozentrum Martinsried, Ludwig-Maximilians-Universität München, München, Germany
| | - Susan A. Joyce
- School of Microbiology and Microbiome Institute, University College Cork, Cork, Ireland
| | - David J. Clarke
- School of Microbiology and Microbiome Institute, University College Cork, Cork, Ireland
| | - Ralf Heermann
- Bereich Mikrobiologie, Biozentrum Martinsried, Ludwig-Maximilians-Universität München, München, Germany
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