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Machado RAR, Malan AP, Boss A, Claasen NJ, Bhat AH, Abolafia J. Photorhabdus africana sp. nov. isolated from Heterorhabditis entomopathogenic nematodes. Curr Microbiol 2024; 81:240. [PMID: 38910178 PMCID: PMC11194217 DOI: 10.1007/s00284-024-03744-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 05/20/2024] [Indexed: 06/25/2024]
Abstract
One Gram-negative, rod-shaped bacterial strain, isolated from an undescribed Heterorhabditis entomopathogenic nematode species was characterized to determine its taxonomic position. The 16S rRNA gene sequences indicate that it belongs to the class Gammaproteobacteria, to the family Morganellaceae, to the genus Photorhabdus, and likely represents a novel bacterial species. This strain, designated here as CRI-LCT, was therefore molecularly, biochemically, and morphologically characterized to describe the novel bacterial species. Phylogenetic reconstructions using 16S rRNA gene sequences show that CRI-LCT is closely related to P. laumondii subsp. laumondii TT01T and to P. laumondii subsp. clarkei BOJ-47T. The 16rRNA gene sequences between CRI-LCT and P. laumondii subsp. laumondii TT01T are 99.1% identical, and between CRI-LCT and P. laumondii subsp. clarkei BOJ-47T are 99.2% identical. Phylogenetic reconstructions using whole genome sequences show that CRI-LCT is closely related to P. laumondii subsp. laumondii TT01T and to P. laumondii subsp. clarkei BOJ-47T. Moreover, digital DNA-DNA hybridization (dDDH) values between CRI-LCT and its two relative species P. laumondii subsp. laumondii TT01T and P. laumondii subsp. clarkei BOJ-47T are 65% and 63%, respectively. In addition, we observed that average nucleotide identity (ANI) values between CRI-LCT and its two relative species P. laumondii subsp. laumondii TT01T and P. laumondii subsp. clarkei BOJ-47T are 95.8% and 95.5%, respectively. These values are below the 70% dDDH and the 95-96% ANI divergence thresholds that delimits prokaryotic species. Based on these genomic divergence values, and the phylogenomic separation, we conclude that CRI-LCT represents a novel bacterial species, for which we propose the name Photorhabdus africana sp. nov. with CRI-LCT (= CCM 9390T = CCOS 2112T) as the type strain. The following biochemical tests allow to differentiate P. africana sp. nov. CRI-LCT from other species of the genus, including its more closely related taxa: β-Galactosidase, citrate utilization, urease and tryptophan deaminase activities, indole and acetoin production, and glucose and inositol oxidation. Our study contributes to a better understanding of the taxonomy and biodiversity of this important bacterial group with great biotechnological and agricultural potential.
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Affiliation(s)
- Ricardo A R Machado
- Experimental Biology Research Group, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland.
| | - Antoinette P Malan
- Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Anja Boss
- Experimental Biology Research Group, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
| | - Nicholle J Claasen
- Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Aashaq Hussain Bhat
- Department of Biosciences and University Center for Research and Development, Chandigarh University, Gharuan, Mohali, Punjab, 140413, India
- Department of Biomaterials, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, Chennai, 600077, India
| | - Joaquín Abolafia
- Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Campus 'Las Lagunillas', Jaén, Spain
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Ogaya C, Huong N, Touceda-González M, Barg M, Dörfler V, Ehlers RU, Molina C. Monitoring the Photorhabdus spp. bacterial load in Heterorhabditis bacteriophora dauer juveniles over different storage times and temperatures: A molecular approach. J Invertebr Pathol 2024; 203:108048. [PMID: 38159796 DOI: 10.1016/j.jip.2023.108048] [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: 10/06/2023] [Revised: 12/22/2023] [Accepted: 12/27/2023] [Indexed: 01/03/2024]
Abstract
Biological control products based on the entomopathogenic nematode Heterorhabditis bacteriophora can vary in virulence (quality). The influence of their symbiotic bacteria Photorhabdus spp. inside the infective dauer juvenile (DJ) on DJ quality has not received much attention in the past. The presence of the bacteria in the DJ is crucial for its biocontrol potential. This investigation provides a method to quantify the bacterial load inside the DJ based on a qPCR technique. Information from the genome of Photorhabdus laumondii strain DE2 was used to identify single copy genes with no homology to any other bacterial accessions. One gene (hereby named CG2) was selected for primers design and for further qPCR experiments. Cross-amplification tests with P. thracensis and P. kayaii, also symbionts of H. bacteriophora, were positive, whereas no amplicons were produced for P. temperata or Xenorhabdus nematophila. We tested our qPCR system in DJ populations carrying defined proportions of bacteria-free (axenic) vs bacteria-carrying nematodes. With an increasing proportion of axenic DJ in a population, virulence declined, and the virulence was proportional to the amount of bacterial DNA detected in the population by qPCR. Along liquid storage over long time, virulence also decreased, and this factor correlated with the reduction of bacterial DNA on the respective DJ population. We observed that stored DJ kept virulent up to 90 days and thereafter the virulence as well as the amount of bacterial DNA drastically decreased. Storage temperature also influenced the bacterial survival. Inside formulated DJ, the loss of bacterial DNA on the DJ population was accelerated under storage temperatures below 7.5 °C, suggesting that reproduction of the bacterial cells takes place when growth temperature is favorable. The role of bacterial survival inside stored DJ can now be adequately addressed using this molecular quality-control technique.
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Affiliation(s)
- Christopher Ogaya
- Faculty of Agricultural and Nutritional Sciences, Christian-Albrechts-University Kiel, Hermann-Rodewald-Str. 4, 24118 Kiel, Germany; e-nema GmbH, Klausdorfer Str. 28-36, 24223 Schwentinental, Germany
| | - Nontarak Huong
- Department of Biology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | | | - Mike Barg
- e-nema GmbH, Klausdorfer Str. 28-36, 24223 Schwentinental, Germany
| | - Verena Dörfler
- e-nema GmbH, Klausdorfer Str. 28-36, 24223 Schwentinental, Germany
| | - Ralf-Udo Ehlers
- Faculty of Agricultural and Nutritional Sciences, Christian-Albrechts-University Kiel, Hermann-Rodewald-Str. 4, 24118 Kiel, Germany; Department of Biology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Carlos Molina
- e-nema GmbH, Klausdorfer Str. 28-36, 24223 Schwentinental, Germany.
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Machado RAR, Bhat AH, Castaneda-Alvarez C, Půža V, San-Blas E. Photorhabdus aballayi sp. nov. and Photorhabdus luminescens subsp. venezuelensis subsp. nov., isolated from Heterorhabditis amazonensis entomopathogenic nematodes. Int J Syst Evol Microbiol 2023; 73. [PMID: 37171451 DOI: 10.1099/ijsem.0.005872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023] Open
Abstract
Six Gram-negative, rod-shaped bacterial strains isolated from Heterorhabditis amazonensis entomopathogenic nematodes were characterized to determine their taxonomic position. 16S rRNA and gyrB gene sequences indicate that they belong to the class Gammaproteobacteria, family Morganellaceae and genus Photorhabdus, and that some of them are conspecifics. Two of them, APURET and JART, were selected for further molecular characterization using whole genome- and whole-proteome-based phylogenetic reconstructions and sequence comparisons. Phylogenetic reconstructions using whole genome and whole proteome sequences show that strains APURET and JART are closely related to Photorhabdus luminescens subsp. luminescens ATCC 29999T and to P. luminescens subsp. mexicana MEX47-22T. Moreover, digital DNA-DNA hybridization (dDDH) values between APURET and P. luminescens subsp. luminescens ATCC 29999T, APURET and P. luminescens subsp. mexicana MEX47-22T, and APURET and JART are 61.6, 61.2 and 64.1 %, respectively. These values are below the 70 % divergence threshold that delimits prokaryotic species. dDDH scores between JART and P. luminescens subsp. luminescens ATCC 29999T and between JART and P. luminescens subsp. mexicana MEX47-22T are 71.9 and 74.8 %, respectively. These values are within the 70 and 79 % divergence thresholds that delimit prokaryotic subspecies. Based on these genomic divergence values, APURET and JART represent two different taxa, for which we propose the names: Photorhabdus aballayi sp. nov. with APURET (=CCM 9236T =CCOS 2019T) as type strain and Photorhabdus luminescens subsp. venezuelensis subsp. nov. with JART (=CCM 9235T =CCOS 2021T) as type strain. Our study contributes to a better understanding of the biodiversity of an important bacterial group with enormous biotechnological and agricultural potential.
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Affiliation(s)
- Ricardo A R Machado
- Experimental Biology Research Group, Institute of Biology. University of Neuchâtel, Neuchâtel, Switzerland
| | - Aashaq Hussain Bhat
- Experimental Biology Research Group, Institute of Biology. University of Neuchâtel, Neuchâtel, Switzerland
- Department of Biosciences, University Center for Research and Development, Chandigarh University, Gharuan, Mohali, 140413, Punjab, India
| | - Carlos Castaneda-Alvarez
- Experimental Biology Research Group, Institute of Biology. University of Neuchâtel, Neuchâtel, Switzerland
- Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas. Universidad de Chile, Santiago, Chile
| | - Vladimir Půža
- Biology Centre CAS, Institute of Entomology, Branišovská 1160/31, 370 05 České Budějovice, Czech Republic
| | - Ernesto San-Blas
- Instituto de Ciencias Agroalimentarias, Animales y Ambientales (ICA3), Universidad de O'Higgins, San Fernando, Chile
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Bhat AH, Machado RAR, Abolafia J, Askary TH, Půža V, Ruiz-Cuenca AN, Rana A, Sayed S, Al-Shuraym LA. Multigene Sequence-Based and Phenotypic Characterization Reveals the Occurrence of a Novel Entomopathogenic Nematode Species, Steinernema anantnagense n. sp. J Nematol 2023; 55:20230029. [PMID: 37455851 PMCID: PMC10341053 DOI: 10.2478/jofnem-2023-0029] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Indexed: 07/18/2023] Open
Abstract
Three entomopathogenic nematode populations were isolated from agricultural fields in the Anantnag district of Jammu and Kashmir (India). Sequences of multiple gene regions and phenotypic features show that they are conspecific and represent a novel species. Molecular and morphological features provided evidence for placing the new species into the "Kushidai" clade. Within this clade, analysis of sequence data of the internal transcribed spacer (ITS) gene, the D2D3 region of the 28S rRNA gene, the mitochondrial cytochrome oxidase I (mtCOI) gene, and the mitochondrial 12S (mt12S) gene depicted the novel species as a distinctive entity closely related to Steinernema akhursti, S. kushidai, and S. populi. Phylogenetic analyses also show that the new species is a sister species to S. akhursti, and these two species are closely related to S. kushidai and S. populi. Additionally, the new species does not mate or produce fertile progeny with any of the closely related species, reinforcing its uniqueness from a biological species concept standpoint. The new species is further characterized by the third-stage infective juveniles with almost straight bodies (0.7-0.8 mm length), poorly developed stoma and pharynx, and conoid-elongate tail (49-66 µm) with hyaline posterior part. Adult females are characterized by short and conoid tails bearing a short mucron in the first generation and long conoid tails with thin mucron in the second generation. Adult males have ventrally curved spicules in both generations. Moreover, the first-generation male has rounded manubrium, fusiform gubernaculum, conoid and slightly ventrally curved tails with minute mucron, and the second generation has rhomboid manubrium anteriorly ventrad bent, and tails with long and robust mucron. The morphological, morphometrical, molecular, and phylogenetic analyses support the new species status of this nematode, which is hereby described as Steinernema anantnagense n. sp. The bacterial symbiont associated with S. anantnagense n. sp. represents a novel species, closely related to Xenorhabdus japonica. These findings shed light on the diversity of entomopathogenic nematodes and their symbiotic bacteria, providing valuable information for future studies in this field.
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Affiliation(s)
- Aashaq Hussain Bhat
- Department of Biosciences and University Center for Research and Development, Chandigarh University, Gharuan, Mohali, Punjab, 140413, India
- Experimental Biology Research Group, Institute of Biology, Faculty of Sciences, University of Neuchâtel, Neuchâtel, Switzerland
| | - Ricardo A. R. Machado
- Experimental Biology Research Group, Institute of Biology, Faculty of Sciences, University of Neuchâtel, Neuchâtel, Switzerland
| | - Joaquín Abolafia
- Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Campus “Las Lagunillas”, Jaén, Spain
| | - Tarique Hassan Askary
- Division of Entomology, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Wadura Campus, Jammu and Kashmir, India
| | - Vladimír Půža
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branišovská 31, 37005České Budějovice, Czech Republic
| | - Alba Nazaret Ruiz-Cuenca
- Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Campus “Las Lagunillas”, Jaén, Spain
| | - Aasha Rana
- Department of Zoology, Faculty of Basic and Applied Sciences, Madhav University, Pindwara (Sirohi), Rajasthan, 307026, India
| | - Samy Sayed
- Department of Economic Entomology and Pesticides, Faculty of Agriculture, Cairo University, 12613, Giza, Egypt
| | - Laila A. Al-Shuraym
- Department of Biology, College of Science, Princess Nourah Bint Abdulrahman University, P.O. Box 84428, Riyadh11671, Saudi Arabia
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Steinernema africanum n. sp. (Rhabditida, Steinernematidae), a New Entomopathogenic Nematode Species Isolated in the Republic of Rwanda. J Nematol 2022; 54:20220049. [DOI: 10.2478/jofnem-2022-0049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Indexed: 11/06/2022] Open
Abstract
Abstract
Alternatives to hazardous insecticides are urgently needed for an environmentally friendly and effective management of insect pests. One such option is the use of entomopathogenic nematodes (EPN). To increase the availability of EPN with potential for biocontrol, we surveyed agricultural soils in the Republic of Rwanda and collected two Steinernema isolates. Initial molecular characterization showed that they represent a new species, for which we propose the name S. africanum n. sp. To describe this new species, we reconstructed phylogenetic relationships, calculated sequence similarity scores, characterized the nematodes at the morphological level, conducted crossing experiments, and isolated and characterized their symbiotic bacteria. At the molecular level, S. africanum n. sp. is closely related to S. litorale and S. weiseri. At the morphological level, S. africanum n. sp. differs from closely related species by the position of the nerve ring and also because the stoma and pharynx region is longer. The first-generation males have ventrally curved spicules with lanceolate manubrium and fusiform gubernaculum and the second-generation males have rounded manubrium and anteriorly hook-like gubernaculum. Steinernema africanum n. sp. does not mate or produce fertile progeny with any of the closely related species.
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Castaneda-Alvarez C, Machado RAR, Morales-Montero P, Boss A, Muller A, Prodan S, Zamorano A, San-Blas E, Půža V, Aballay E. Photorhabdus antumapuensis sp. nov., a novel symbiotic bacterial species associated with Heterorhabditis atacamensis entomopathogenic nematodes. Int J Syst Evol Microbiol 2022; 72. [DOI: 10.1099/ijsem.0.005525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
One motile, Gram-negative, non-spore-forming and rod-shaped symbiotic bacterium, strain UCH-936T, was isolated from Heterorhabditis atacamensis nematodes. Results of biochemical, physiological, molecular and genomic analyses suggest that it represents a new species, which we propose to name Photorhabdus antumapuensis sp. nov. Digital DNA–DNA hybridization shows that strain UCH-936T is more closely related to
Photorhabdus kleinii
DSM 23513T, but shares solely 50.5 % similarity, which is below the 70% cut-off value that delimits species boundaries in bacteria. Phylogenetic reconstructions using whole-genome sequences show that strain UCH-936T forms a unique clade, suggesting its novel and distinct taxonomic status again. Similarly, comparative genomic analyses shows that the virulence factor flagella-related gene fleR, the type IV pili-related gene pilL and the vibriobactin-related gene vibE are present in the genome of strain UCH-936T but absent in the genomes of its closest relatives. Biochemically and physiologically, UCH-936T differs also from all closely related
Photorhabdus
species. Therefore, Photorhabdus antumapuensis sp. nov. is proposed as a new species with the type strain UCH-936T (CCCT 21.06T=CCM 9188T=CCOS 1991T).
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Affiliation(s)
- Carlos Castaneda-Alvarez
- Programa de Doctorado en Ciencias Silvoagropecuarias y Veterinarias, Campus Sur Universidad de Chile, Santa Rosa 11315, La Pintana, Santiago, CP 8820808, Chile
- Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas, Universidad de Chile, P.O. Box 1004, Santiago, Chile
| | - Ricardo A. R. Machado
- Experimental Biology Research Group, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Patricia Morales-Montero
- Departamento de Ciencias Vegetales, Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Macul, Santiago, Chile
- Experimental Biology Research Group, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Anja Boss
- Experimental Biology Research Group, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Arthur Muller
- Experimental Biology Research Group, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Simona Prodan
- Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas, Universidad de Chile, P.O. Box 1004, Santiago, Chile
| | - Alan Zamorano
- Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas, Universidad de Chile, P.O. Box 1004, Santiago, Chile
| | - Ernesto San-Blas
- Instituto de Ciencias Agroalimentarias, Animales y Ambientales (ICA3), Universidad de O'Higgins, San Pedro, San José Province, Chile
| | - Vladimír Půža
- Laboratory of Entomopathogenic Nematodes, Institute of Entomology, Biology Centre CAS, Branišovská 31, České Budějovice, 370 05, Czechia
| | - Erwin Aballay
- Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas, Universidad de Chile, P.O. Box 1004, Santiago, Chile
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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: 4] [Impact Index Per Article: 2.0] [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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Booysen E, Malan AP, Dicks LM. Colour of Heterorhabditis zealandica-infected-Galleria mellonella dependent on the Photorhabdus symbiont, with two new nematode-symbiotic associations reported. J Invertebr Pathol 2022; 189:107729. [DOI: 10.1016/j.jip.2022.107729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 01/24/2022] [Accepted: 01/31/2022] [Indexed: 10/19/2022]
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Castaneda-Alvarez C, Prodan S, Zamorano A, San-Blas E, Aballay E. Xenorhabdus lircayensis sp. nov., the symbiotic bacterium associated with the entomopathogenic nematode Steinernema unicornum. Int J Syst Evol Microbiol 2021; 71. [PMID: 34898417 DOI: 10.1099/ijsem.0.005151] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Xenorhabdus is a symbiotic group of bacteria associated with entomopathogenic nematodes of the family Steinernematidae. Although the described Steirnernema species list is extensive, not all their symbiotic bacteria have been identified. One single motile, Gram-negative and non-spore-forming rod-shaped symbiotic bacterium, strain VLST, was isolated from the entomopathogenic nematode Steinernema unicornum. Analyses of the 16S rRNA gene determined that the VLST isolate belongs to the genus Xenorhabdus, and its closest related species is Xenorhabdus szentirmaii DSM 16338T (98.2 %). Deeper analyses using the whole genome for phylogenetic reconstruction indicate that VLST exhibits a unique clade in the genus. Genomic comparisons considering digital DNA-DNA hybridization (dDDH) values confirms this result, showing that the VLST values are distant enough from the 70 % threshold suggested for new species, sharing 30.7, 30.5 and 30.3 % dDDH with Xenorhabdus khoisanae MCB, Xenorhabdus koppenhoeferi DSM 18168T and Xenorhabdus miraniensis DSM 18168T, respectively, as the closest species. Detailed physiological, biochemical and chemotaxonomic tests of the VLST isolate reveal consistent differences from previously described Xenorhabdus species. Phylogenetic, physiological, biochemical and chemotaxonomic approaches show that VLST represents a new species of the genus Xenorhabdus, for which the name Xenorhabdus lircayensis sp. nov. (type strain VLST=CCCT 20.04T=DSM 111583T) is proposed.
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Affiliation(s)
- Carlos Castaneda-Alvarez
- Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas, Universidad de Chile, Chile.,Programa de Doctorado en Ciencias Silvoagropecuarias y Veterinarias, Campus Sur Universidad de Chile, Santa Rosa 11315, La Pintana, Santiago, CP: 8820808, Chile
| | - Simona Prodan
- Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas, Universidad de Chile, Chile
| | - Alan Zamorano
- Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas, Universidad de Chile, Chile
| | - Ernesto San-Blas
- Instituto de Ciencias Agroalimentarias, Animales y Ambientales (ICA3), Universidad de O'Higgins, O'Higgins, Chile
| | - Erwin Aballay
- Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas, Universidad de Chile, Chile
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Machado RA, Bhat AH, Abolafia J, Muller A, Bruno P, Fallet P, Arce CC, Turlings TC, Bernal JS, Kajuga J, Waweru B, Toepfer S. Multi-locus phylogenetic analyses uncover species boundaries and reveal the occurrence of two new entomopathogenic nematode species, Heterorhabditis ruandica n. sp. and Heterorhabditis zacatecana n. sp. J Nematol 2021; 53:e2021-89. [PMID: 34790901 PMCID: PMC8588743 DOI: 10.21307/jofnem-2021-089] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Indexed: 11/17/2022] Open
Abstract
Species of the nematode genus Heterorhabditis are important biological control agents against agricultural pests. The taxonomy of this group is still unclear as it currently relies on phylogenetic reconstructions based on a few genetic markers with little resolutive power, specially of closely related species. To fill this knowledge gap, we sequenced several phylogenetically relevant genetic loci and used them to reconstruct phylogenetic trees, to calculate sequence similarity scores, and to determine signatures of species- and population-specific genetic polymorphism. In addition, we revisited the current literature related to the description, synonymisation, and declaration as species inquirendae of Heterorhabditis species to compile taxonomically relevant morphological and morphometric characters, characterized new nematode isolates at the morphological and morphometrical level, and conducted self-crossing and cross-hybridization experiments. The results of this study show that the sequences of the mitochondrial cytochrome C oxidase subunit I (COI) gene provide better phylogenetic resolutive power than the sequences of nuclear rRNA genes and that this gene marker can phylogenetically resolve closely related species and even populations of the same species with high precision. Using this gene marker, we found two new species, Heterorhabditis ruandica n. sp. and Heterorhabditis zacatecana n. sp. A detailed characterization of these species at the morphological and morphometric levels and nematode reproduction assays revealed that the threshold for species delimitation in this genus, using COI sequences, is 97% to 98%. Our study illustrates the importance of rigorous morphological and morphometric characterization and multi-locus sequencing for the description of new species within the genus Heterorhabditis, serves to clarify the phylogenetic relationships of this important group of biological control agents, and can inform future species descriptions to advance our efforts towards developing more tools for sustainable and environmentally friendly agriculture.
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Affiliation(s)
- Ricardo A.R. Machado
- Experimental Biology Research Group. Institute of Biology. Faculty of Sciences. University of Neuchâtel. Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
| | - Aashaq Hussain Bhat
- Department of Zoology, Government Degree College. Billawar-184204, Kathua, Jammu, Jammu and Kashmir, India
| | - Joaquín Abolafia
- Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Campus ‘Las Lagunillas’ s/n, Edificio B3, 23071 Jaén, Spain
| | - Arthur Muller
- Experimental Biology Research Group. Institute of Biology. Faculty of Sciences. University of Neuchâtel. Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
| | - Pamela Bruno
- Laboratory of Fundamental and Applied Research in Chemical Ecology, Institute of Biology. Faculty of Sciences, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Patrick Fallet
- Laboratory of Fundamental and Applied Research in Chemical Ecology, Institute of Biology. Faculty of Sciences, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Carla C.M. Arce
- Laboratory of Fundamental and Applied Research in Chemical Ecology, Institute of Biology. Faculty of Sciences, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Ted C.J. Turlings
- Laboratory of Fundamental and Applied Research in Chemical Ecology, Institute of Biology. Faculty of Sciences, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Julio S. Bernal
- Department of Entomology, Texas A&M University, College Station, TX
| | - Joelle Kajuga
- Department of Crop Innovations & Technology Transfer. Rwanda Agriculture and Animal Resources Development Board, 5016 Kigali-Rwanda
| | - Bancy Waweru
- Department of Crop Innovations & Technology Transfer. Rwanda Agriculture and Animal Resources Development Board, 5016 Kigali-Rwanda
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Photorhabdus spp.: An Overview of the Beneficial Aspects of Mutualistic Bacteria of Insecticidal Nematodes. PLANTS 2021; 10:plants10081660. [PMID: 34451705 PMCID: PMC8401807 DOI: 10.3390/plants10081660] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 07/29/2021] [Accepted: 08/03/2021] [Indexed: 11/17/2022]
Abstract
The current approaches to sustainable agricultural development aspire to use safer means to control pests and pathogens. Photorhabdus bacteria that are insecticidal symbionts of entomopathogenic nematodes in the genus Heterorhabditis can provide such a service with a treasure trove of insecticidal compounds and an ability to cope with the insect immune system. This review highlights the need of Photorhabdus-derived insecticidal, fungicidal, pharmaceutical, parasiticidal, antimicrobial, and toxic materials to fit into current, or emerging, holistic strategies, mainly for managing plant pests and pathogens. The widespread use of these bacteria, however, has been slow, due to cost, natural presence within the uneven distribution of their nematode partners, and problems with trait stability during in vitro culture. Yet, progress has been made, showing an ability to overcome these obstacles via offering affordable mass production and mastered genome sequencing, while detecting more of their beneficial bacterial species/strains. Their high pathogenicity to a wide range of arthropods, efficiency against diseases, and versatility, suggest future promising industrial products. The many useful properties of these bacteria can facilitate their integration with other pest/disease management tactics for crop protection.
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