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Chandrakasan G, García-Trejo JF, Feregrino-Pérez AA, Aguirre-Becerra H, García ER, Nieto-Ramírez MI. Preliminary Screening on Antibacterial Crude Secondary Metabolites Extracted from Bacterial Symbionts and Identification of Functional Bioactive Compounds by FTIR, HPLC and Gas Chromatography-Mass Spectrometry. Molecules 2024; 29:2914. [PMID: 38930979 PMCID: PMC11206551 DOI: 10.3390/molecules29122914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/02/2024] [Accepted: 06/06/2024] [Indexed: 06/28/2024] Open
Abstract
Secondary metabolites, bioactive compounds produced by living organisms, can unveil symbiotic relationships in nature. In this study, soilborne entomopathogenic nematodes associated with symbiotic bacteria (Xenorhabdus stockiae and Photorhabdus luminescens) were extracted from solvent supernatant containing secondary metabolites, demonstrating significant inhibitory effects against E. coli, S. aureus, B. subtilus, P. mirabilis, E. faecalis, and P. stutzeri. The characterization of these secondary metabolites by Fourier transforms infrared spectroscopy revealed amine groups of proteins, hydroxyl and carboxyl groups of polyphenols, hydroxyl groups of polysaccharides, and carboxyl groups of organic acids. Furthermore, the obtained crude extracts were analyzed by high-performance liquid chromatography for the basic identification of potential bioactive peptides. Gas chromatography-mass spectrometry analysis of ethyl acetate extracts from Xenorhabdus stockiae identified major compounds including nonanoic acid derivatives, proline, paromycin, octodecanal derivatives, trioxa-5-aza-1-silabicyclo, 4-octadecenal, methyl ester, oleic acid, and 1,2-benzenedicarboxylicacid. Additional extraction from Photorhabdus luminescens yielded functional compounds such as indole-3-acetic acid, phthalic acid, 1-tetradecanol, nemorosonol, 1-eicosanol, and unsaturated fatty acids. These findings support the potential development of novel natural antimicrobial agents for future pathogen suppression.
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Affiliation(s)
- Gobinath Chandrakasan
- División de Estudios de Posgrado, Facultad de Ingeniería, Universidad Autónoma de Querétaro, Santiago de Querétaro 76010, Querétaro, Mexico; (A.A.F.-P.); (H.A.-B.); (E.R.G.); (M.I.N.-R.)
| | - Juan Fernando García-Trejo
- División de Estudios de Posgrado, Facultad de Ingeniería, Universidad Autónoma de Querétaro, Santiago de Querétaro 76010, Querétaro, Mexico; (A.A.F.-P.); (H.A.-B.); (E.R.G.); (M.I.N.-R.)
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Huang X, Tang Q, Liu S, Li C, Li Y, Sun Y, Ding X, Xia L, Hu S. Discovery of an antitumor compound from xenorhabdus stockiae HN_xs01. World J Microbiol Biotechnol 2024; 40:101. [PMID: 38366186 DOI: 10.1007/s11274-024-03915-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 02/01/2024] [Indexed: 02/18/2024]
Abstract
Xenorhabdus, known for its symbiotic relationship with Entomopathogenic nematodes (EPNs), belongs to the Enterobacteriaceae family. This dual-host symbiotic nematode exhibits pathogenic traits, rendering it a promising biocontrol agent against insects. Our prior investigations revealed that Xenorhabdus stockiae HN_xs01, isolated in our laboratory, demonstrates exceptional potential in halting bacterial growth and displaying anti-tumor activity. Subsequently, we separated and purified the supernatant of the HN_xs01 strain and obtained a new compound with significant inhibitory activity on tumor cells, which we named XNAE. Through LC-MS analysis, the mass-to-nucleus ratio of XNAE was determined to be 254.24. Our findings indicated that XNAE exerts a time- and dose-dependent inhibition on B16 and HeLa cells. After 24 h, its IC50 for B16 and HeLa cells was 30.178 µg/mL and 33.015 µg/mL, respectively. Electron microscopy revealed conspicuous damage to subcellular structures, notably mitochondria and the cytoskeleton, resulting in a notable reduction in cell numbers among treated tumor cells. Interestingly, while XNAE exerted a more pronounced inhibitory effect on B16 cells compared to HeLa cells, it showed no discernible impact on HUVEC cells. Treatment of B16 cells with XNAE induced early apoptosis and led to cell cycle arrest in the G2 phase, as evidenced by flow cytometry analysis. The impressive capability of X. stockiae HN_xs01 in synthesizing bioactive secondary metabolites promises to significantly expand the reservoir of natural products. Further exploration to identify the bioactivity of these compounds holds the potential to shed light on their roles in bacteria-host interaction. Overall, these outcomes underscore the promising potential of XNAE as a bioactive compound for tumor treatment.
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Affiliation(s)
- Xiyin Huang
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory of Microbial Molecular Biology, College of Life Science, Hunan Normal University, No.36 Lushan Street, Changsha, 410081, China
| | - Qiong Tang
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory of Microbial Molecular Biology, College of Life Science, Hunan Normal University, No.36 Lushan Street, Changsha, 410081, China
| | - Siqin Liu
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory of Microbial Molecular Biology, College of Life Science, Hunan Normal University, No.36 Lushan Street, Changsha, 410081, China
| | - Chen Li
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory of Microbial Molecular Biology, College of Life Science, Hunan Normal University, No.36 Lushan Street, Changsha, 410081, China
| | - Yaoguang Li
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory of Microbial Molecular Biology, College of Life Science, Hunan Normal University, No.36 Lushan Street, Changsha, 410081, China
| | - Yunjun Sun
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory of Microbial Molecular Biology, College of Life Science, Hunan Normal University, No.36 Lushan Street, Changsha, 410081, China
| | - Xuezhi Ding
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory of Microbial Molecular Biology, College of Life Science, Hunan Normal University, No.36 Lushan Street, Changsha, 410081, China
| | - Liqiu Xia
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory of Microbial Molecular Biology, College of Life Science, Hunan Normal University, No.36 Lushan Street, Changsha, 410081, China
| | - Shengbiao Hu
- State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory of Microbial Molecular Biology, College of Life Science, Hunan Normal University, No.36 Lushan Street, Changsha, 410081, China.
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Palma L, Frizzo L, Kaiser S, Berry C, Caballero P, Bode HB, Del Valle EE. Genome Sequence Analysis of Native Xenorhabdus Strains Isolated from Entomopathogenic Nematodes in Argentina. Toxins (Basel) 2024; 16:108. [PMID: 38393187 PMCID: PMC10892061 DOI: 10.3390/toxins16020108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 02/05/2024] [Accepted: 02/13/2024] [Indexed: 02/25/2024] Open
Abstract
Entomopathogenic nematodes from the genus Steinernema (Nematoda: Steinernematidae) are capable of causing the rapid killing of insect hosts, facilitated by their association with symbiotic Gram-negative bacteria in the genus Xenorhabdus (Enterobacterales: Morganellaceae), positioning them as interesting candidate tools for the control of insect pests. In spite of this, only a limited number of species from this bacterial genus have been identified from their nematode hosts and their insecticidal properties documented. This study aimed to perform the genome sequence analysis of fourteen Xenorhabdus strains that were isolated from Steinernema nematodes in Argentina. All of the strains were found to be able of killing 7th instar larvae of Galleria mellonella (L.) (Lepidoptera: Pyralidae). Their sequenced genomes harbour 110 putative insecticidal proteins including Tc, Txp, Mcf, Pra/Prb and App homologs, plus other virulence factors such as putative nematocidal proteins, chitinases and secondary metabolite gene clusters for the synthesis of different bioactive compounds. Maximum-likelihood phylogenetic analysis plus average nucleotide identity calculations strongly suggested that three strains should be considered novel species. The species name for strains PSL and Reich (same species according to % ANI) is proposed as Xenorhabdus littoralis sp. nov., whereas strain 12 is proposed as Xenorhabdus santafensis sp. nov. In this work, we present a dual insight into the biocidal potential and diversity of the Xenorhabdus genus, demonstrated by different numbers of putative insecticidal genes and biosynthetic gene clusters, along with a fresh exploration of the species within this genus.
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Affiliation(s)
- Leopoldo Palma
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Departamento de Genética, Universitat de València, 46100 Burjassot, Spain
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires C1033AAJ, Argentina
- Instituto Multidisciplinario de Investigación y Transferencia Agroalimentaria y Biotecnológica (IMITAB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Villa María (UNVM), Villa María 1555, Argentina
| | - Laureano Frizzo
- ICIVET Litoral, CONICET-UNL, Departamento de Salud Pública, Facultad de Ciencias Veterinarias, Universidad Nacional del Litoral, Esperanza S3080, Argentina;
| | - Sebastian Kaiser
- Department of Natural Products in Organismic Interactions, Max-Planck-Institute for Terrestrial Microbiology, 35043 Marburg, Germany; (S.K.); (H.B.B.)
- Evolutionary Biochemistry Group, Max-Planck-Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Colin Berry
- Cardiff School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK;
| | - Primitivo Caballero
- Institute for Multidisciplinary Research in Applied Biology, Universidad Pública de Navarra, 31006 Pamplona, Spain;
- Departamento de Investigación y Desarrollo, Bioinsectis SL, Polígono Industrial Mocholi Plaza Cein 5, Nave A14, 31110 Noain, Spain
| | - Helge B. Bode
- Department of Natural Products in Organismic Interactions, Max-Planck-Institute for Terrestrial Microbiology, 35043 Marburg, Germany; (S.K.); (H.B.B.)
- Molecular Biotechnology, Department of Biosciences, Goethe Universität Frankfurt, 60438 Frankfurt, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Phillips University Marburg, 35043 Marburg, Germany
- Department of Chemistry, Phillips University Marburg, 35043 Marburg, Germany
- Senckenberg Gesellschaft für Naturforschung, 60325 Frankfurt, Germany
| | - Eleodoro Eduardo Del Valle
- ICiagro Litoral, CONICET, Facultad de Ciencias Agrarias, Universidad Nacional del Litoral, Kreder 2805, Esperanza S3080, Argentina
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Awori RM, Waturu CN, Pidot SJ, Amugune NO, Bode HB. Draft genomes, phylogenomic reconstruction and comparative genome analysis of three Xenorhabdus strains isolated from soil-dwelling nematodes in Kenya. Access Microbiol 2023; 5:acmi000531.v4. [PMID: 37323942 PMCID: PMC10267655 DOI: 10.1099/acmi.0.000531.v4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/27/2023] [Indexed: 06/17/2023] Open
Abstract
As a proven source of potent and selective antimicrobials, Xenorhabdus bacteria are important to an age plagued with difficult-to-treat microbial infections. Yet, only 27 species have been described to date. In this study, a novel Xenorhabdus species was discovered through genomic studies on three isolates from Kenyan soils. Soils in Western Kenya were surveyed for steinernematids and Steinernema isolates VH1 and BG5 were recovered from red volcanic loam soils from cultivated land in Vihiga and clay soils from riverine land in Bungoma respectively. From the two nematode isolates, Xenorhabdus sp. BG5 and Xenorhabdus sp. VH1 were isolated. The genomes of these two, plus that of X. griffiniae XN45 - this was previously isolated from Steinernema sp. scarpo that also originated from Kenyan soils - were sequenced and assembled. Nascent genome assemblies of the three isolates were of good quality with over 70 % of their proteome having known functions. These three isolates formed the X. griffiniae clade in a phylogenomic reconstruction of the genus. Their species were delineated using three overall genome relatedness indices: an unnamed species of the genus, Xenorhabdus sp. BG5, X. griffiniae VH1 and X. griffiniae XN45. A pangenome analysis of this clade revealed that over 70 % of species-specific genes encoded unknown functions. Transposases were linked to genomic islands in Xenorhabdus sp. BG5. Thus, overall genome-related indices sufficiently delineated species of two new Xenorhabdus isolates from Kenya, both of which were closely related to X. griffiniae . The functions encoded by most species-specific genes in the X. griffiniae clade remain unknown.
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Affiliation(s)
- Ryan Musumba Awori
- Molecular Biotechnology, Department of Biosciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
- Elakistos Biosciences, PO Box 19301-00100, Nairobi, Kenya
| | - Charles N. Waturu
- Horticulture Research Institute, Kenya Agricultural and Livestock Research Organisation, PO Box 220 Thika
| | - Sacha J. Pidot
- Department of Microbiology and Immunology at the Doherty Institute, University of Melbourne, Melbourne, Australia
| | - Nelson O. Amugune
- Department of Biology, University of Nairobi, PO Box 30197-00100, Nairobi, Kenya
| | - Helge B. Bode
- Molecular Biotechnology, Department of Biosciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
- Department of Natural Products in Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
- Chemical Biology, Department of Chemistry, Phillips University Marburg, 35043 Marburg, Germany
- Senckenberg Gesellschaft für Naturforschung, 60325 Frankfurt am Main, Germany
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Awori RM. Nematophilic bacteria associated with entomopathogenic nematodes and drug development of their biomolecules. Front Microbiol 2022; 13:993688. [PMID: 36187939 PMCID: PMC9520725 DOI: 10.3389/fmicb.2022.993688] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 08/24/2022] [Indexed: 11/30/2022] Open
Abstract
The importance of Xenorhabdus and Photorhabdus symbionts to their respective Steinernema and Heterorhabditis nematode hosts is that they not only contribute to their entomopathogenicity but also to their fecundity through the production of small molecules. Thus, this mini-review gives a brief introductory overview of these nematophilic bacteria. Specifically, their type species, nematode hosts, and geographic region of isolations are tabulated. The use of nucleotide sequence-based techniques for their species delineation and how pangenomes can improve this are highlighted. Using the Steinernema–Xenorhabdus association as an example, the bacterium-nematode lifecycle is visualized with an emphasis on the role of bacterial biomolecules. Those currently in drug development are discussed, and two potential antimalarial lead compounds are highlighted. Thus, this mini-review tabulates forty-eight significant nematophilic bacteria and visualizes the ecological importance of their biomolecules. It further discusses three of these biomolecules that are currently in drug development. Through it, one is introduced to Xenorhabdus and Photorhabdus bacteria, their natural production of biomolecules in the nematode-bacterium lifecycle, and how these molecules are useful in developing novel therapies.
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Affiliation(s)
- Ryan Musumba Awori
- Department of Biology, University of Nairobi, Nairobi, Kenya
- Elakistos Biosciences, Nairobi, Kenya
- *Correspondence: Ryan Musumba Awori,
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Toopaang W, Bunnak W, Srisuksam C, Wattananukit W, Tanticharoen M, Yang YL, Amnuaykanjanasin A. Microbial polyketides and their roles in insect virulence: from genomics to biological functions. Nat Prod Rep 2022; 39:2008-2029. [PMID: 35822627 DOI: 10.1039/d1np00058f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Covering: May 1966 up to January 2022Entomopathogenic microorganisms have potential for biological control of insect pests. Their main secondary metabolites include polyketides, nonribosomal peptides, and polyketide-nonribosomal peptide (PK-NRP) hybrids. Among these secondary metabolites, polyketides have mainly been studied for structural identification, pathway engineering, and for their contributions to medicine. However, little is known about the function of polyketides in insect virulence. This review focuses on the role of bacterial and fungal polyketides, as well as PK-NRP hybrids in insect infection and killing. We also discuss gene distribution and evolutional relationships among different microbial species. Further, the role of microbial polyketides and the hybrids in modulating insect-microbial symbiosis is also explored. Understanding the mechanisms of polyketides in insect pathogenesis, how compounds moderate the host-fungus interaction, and the distribution of PKS genes across different fungi and bacteria will facilitate the discovery and development of novel polyketide-derived bio-insecticides.
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Affiliation(s)
- Wachiraporn Toopaang
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Rd., Khlong Nueng, Amphoe Khlong Luang, Pathum Thani 12120, Thailand. .,Molecular and Biological Agricultural Sciences, Taiwan International Graduate Program, Academia Sinica and National Chung Hsing University, Taiwan.,Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan.
| | - Warapon Bunnak
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Rd., Khlong Nueng, Amphoe Khlong Luang, Pathum Thani 12120, Thailand.
| | - Chettida Srisuksam
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Rd., Khlong Nueng, Amphoe Khlong Luang, Pathum Thani 12120, Thailand.
| | - Wilawan Wattananukit
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Rd., Khlong Nueng, Amphoe Khlong Luang, Pathum Thani 12120, Thailand.
| | - Morakot Tanticharoen
- School of Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand
| | - Yu-Liang Yang
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan. .,Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan 711010, Taiwan
| | - Alongkorn Amnuaykanjanasin
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Rd., Khlong Nueng, Amphoe Khlong Luang, Pathum Thani 12120, Thailand.
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Natural products from Photorhabdus and Xenorhabdus: mechanisms and impacts. Appl Microbiol Biotechnol 2022; 106:4387-4399. [PMID: 35723692 DOI: 10.1007/s00253-022-12023-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 06/07/2022] [Accepted: 06/09/2022] [Indexed: 12/21/2022]
Abstract
Insects and fungal pathogens pose constant problems to public health and agriculture, especially in resource-limited parts of the world; and the use of chemical pesticides continues to be the main methods for the control of these organisms. Photorhabdus spp. and Xenorhabdus spp., (Fam; Morganellaceae), enteric symbionts of Steinernema, and Heterorhabditis nematodes are naturally found in soil on all continents, except Antarctic, and on many islands throughout the world. These bacteria produce diverse secondary metabolites that have important biological and ecological functions. Secondary metabolites include non-ribosomal peptides, polyketides, and/or hybrid natural products that are synthesized using polyketide synthetase (PRS), non-ribosomal peptide synthetase (NRPS), or similar enzymes and are sources of new pesticide/drug compounds and/or can serve as lead molecules for the design and synthesize of new alternatives that could replace current ones. This review addresses the effects of these bacterial symbionts on insect pests, fungal phytopathogens, and animal pathogens and discusses the substances, mechanisms, and impacts on agriculture and public health. KEY POINTS: • Insects and fungi are a constant menace to agricultural and public health. • Chemical-based control results in resistance development. • Photorhabdus and Xenorhabdus are compelling sources of biopesticides.
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Santos-Aberturas J, Vior NM. Beyond Soil-Dwelling Actinobacteria: Fantastic Antibiotics and Where to Find Them. Antibiotics (Basel) 2022; 11:195. [PMID: 35203798 PMCID: PMC8868522 DOI: 10.3390/antibiotics11020195] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/27/2022] [Accepted: 01/29/2022] [Indexed: 12/10/2022] Open
Abstract
Bacterial secondary metabolites represent an invaluable source of bioactive molecules for the pharmaceutical and agrochemical industries. Although screening campaigns for the discovery of new compounds have traditionally been strongly biased towards the study of soil-dwelling Actinobacteria, the current antibiotic resistance and discovery crisis has brought a considerable amount of attention to the study of previously neglected bacterial sources of secondary metabolites. The development and application of new screening, sequencing, genetic manipulation, cultivation and bioinformatic techniques have revealed several other groups of bacteria as producers of striking chemical novelty. Biosynthetic machineries evolved from independent taxonomic origins and under completely different ecological requirements and selective pressures are responsible for these structural innovations. In this review, we summarize the most important discoveries related to secondary metabolites from alternative bacterial sources, trying to provide the reader with a broad perspective on how technical novelties have facilitated the access to the bacterial metabolic dark matter.
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Affiliation(s)
| | - Natalia M. Vior
- Department of Molecular Microbiology, John Innes Centre, Norwich NR7 4UH, UK
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Booysen E, Rautenbach M, Stander MA, Dicks LMT. Profiling the Production of Antimicrobial Secondary Metabolites by Xenorhabdus khoisanae J194 Under Different Culturing Conditions. Front Chem 2021; 9:626653. [PMID: 33859975 PMCID: PMC8042232 DOI: 10.3389/fchem.2021.626653] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 02/11/2021] [Indexed: 11/13/2022] Open
Abstract
Species from the genus Xenorhabdus, endosymbiotic bacteria of Steinernema nematodes, produce several antibacterial and antifungal compounds, some of which are anti-parasitic. In this study, we report on the effect growth conditions have on the production of antimicrobial compounds produced by Xenorhabdus khoisanae J194. The strain was cultured in aerated and non-aerated broth, respectively, and on solid media. Production of antimicrobial compounds was detected after 24 h of growth in liquid media, with highest levels recorded after 96 h. Highest antimicrobial activity was obtained from cells cultured on solid media. By using ultraperformance liquid chromatography linked to mass spectrometry and HPLC, a plethora of known Xenorhabdus compounds were identified. These compounds are the PAX lipopeptides (PAX 1', PAX 3', PAX 5, and PAX 7E), xenocoumacins and xenoamicins. Differences observed in the MS-MS fractionation patterns collected in this study, when compared to previous studies indicated that this strain produces novel xenoamicins. Three novel antimicrobial compounds, khoicin, xenopep and rhabdin, were identified and structurally characterized based on MS-MS fractionation patterns, amino acid analysis and whole genome analysis. The various compounds produced under the three different conditions indicates that the secondary metabolism of X. khoisanae J194 may be regulated by oxygen, water activity or both. Based on these findings X. khoisanae J194 produce a variety of antimicrobial compounds that may have application in disease control.
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Affiliation(s)
- Elzaan Booysen
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
| | - Marina Rautenbach
- Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa
| | - Marietjie A Stander
- Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa.,LCMS Central Analytical Facility, Stellenbosch University, Stellenbosch, South Africa
| | - Leon M T Dicks
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
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