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Machado RAR, Bhat AH, Castaneda-Alvarez C, Askary TH, Půža V, Pagès S, Abolafia J. Xenorhabdus aichiensis sp. nov., Xenorhabdus anantnagensis sp. nov., and Xenorhabdus yunnanensis sp. nov., Isolated from Steinernema Entomopathogenic Nematodes. Curr Microbiol 2023; 80:300. [PMID: 37493817 PMCID: PMC10371910 DOI: 10.1007/s00284-023-03373-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 06/12/2023] [Indexed: 07/27/2023]
Abstract
Three bacterial strains, XENO-2T, XENO-7T, and XENO-10T, isolated from Steinernema entomopathogenic nematodes, were found to represent novel Xenorhabdus species. In this study, we describe these new species by whole-genome and whole-proteome phylogenomic reconstructions, by calculating sequence identity scores using core genome sequences, and by phenotypic characterization. Phylogenomic reconstructions using ribosomal and house-keeping genes, and whole-genome and whole-proteome sequences show that XENO-2T and XENO-10T are closely related to Xenorhabdus japonica DSM 16522T and that XENO-7T is closely related to Xenorhabdus bovienii subsp. africana XENO-1T and to X. bovienii subsp. bovienii T228T. The dDDH values between XENO-2T and XENO-10T and between XENO-2T and X. japonica DSM 16522T are 56.4 and 51.8%, respectively. The dDDH value between XENO-10T and X. japonica DSM 16522T is 53.4%. The dDDH values between XENO-7T and X. bovienii subsp. africana XENO-1T and between XENO-7T and X. bovienii subsp. bovienii T228T are 63.6 and 69.4%, respectively. These dDDH values are below the 70% divergence threshold for prokaryotic species delineation. The newly described species are highly pathogenic to G. mellonella larvae, grow at pH between 5 and 9 (optimum 5-7), at salt concentrations of 1-3% (optimum 1-2%), and temperatures between 20 and 37 °C (optimum 28-30 °C). Biochemical tests such as lysine decarboxylase, ornithine decarboxylase, urease, gelatinase, citrate utilization, indole and acetoin production, and cytochrome oxidase tests allow to differentiate the novel species from their more closely related species. Considering these genetic and phenotypic divergencies, we propose the following new species: Xenorhabdus aichiensis sp. nov. with XENO-7T (= CCM 9233T = CCOS 2024T) as the type strain, Xenorhabdus anantnagensis sp. nov., with XENO-2T (= CCM 9237T = CCOS 2023T) as the type strain, and Xenorhabdus yunnanensis sp. nov., with XENO-10T (= CCM 9322T = CCOS 2071T) as the type strain. Our study contributes to a better understanding of the biodiversity and phylogenetic relationships of entomopathogenic bacteria associated with insect parasitic nematodes.
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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.
| | - Aashaq Hussain Bhat
- Experimental Biology Research Group, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
- Department of Biosciences, University Center for Research and Development, Chandigarh University, Mohali, Punjab, India
| | - Carlos Castaneda-Alvarez
- Experimental Biology Research Group, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
- Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas, Universidad de Chile, Santiago, Chile
| | - Tarique Hassan Askary
- Division of Entomology, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences and Technology, Wadura Campus, Jammu, Jammu and Kashmir, India
| | - Vladimir Půža
- Biology Centre CAS, Institute of Entomology, České Budějovice, Czech Republic
| | - Sylvie Pagès
- INRAe, Université de Montpellier, Montpellier, France
| | - Joaquín Abolafia
- Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Campus 'Las Lagunillas', Jaén, Spain
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2
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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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Machado RAR, Somvanshi VS, Muller A, Kushwah J, Bhat CG. Photorhabdus hindustanensis sp. nov., Photorhabdus akhurstii subsp. akhurstii subsp. nov. , and Photorhabdus akhurstii subsp. bharatensis subsp. nov. , isolated from Heterorhabditis entomopathogenic nematodes. Int J Syst Evol Microbiol 2021; 71. [PMID: 34524954 DOI: 10.1099/ijsem.0.004998] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Two Gram-negative, rod-shaped bacteria, H1T and H3T, isolated from the digestive tract of Heterorhabditis entomopathogenic nematodes were biochemically and molecularly characterized to determine their taxonomic positions. The 16S rRNA gene sequences of these strains indicate that they belong to the Gammaproteobacteria, to the family Morganellaceae, and to the Photorhabdus genus. Deeper analyses using whole genome-based phylogenetic reconstructions show that strains H1T and H3T are closely related to P. akhurstii DSM 15138T, to P. hainanensis DSM 22397T, and to P. namnaonensis PB45.5T. In silico genomic comparisons confirm these observations and show that strain H1T shares 70.6, 66.8, and 63.5 % digital DNA-DNA hybridization (dDDH) with P. akhurstii DSM 15138T, P. hainanensis DSM 22397T, and P. namnaonensis PB45.5T, respectively, and that strain H3T shares 76.6, 69.4, and 59.2 % dDDH with P. akhurstii DSM 15138T, P. hainanensis DSM 22397T, and P. namnaonensis PB45.5T, respectively. Physiological and biochemical characterization reveals that these two strains differ from most of the validly described Photorhabdus species and from their more closely related taxa. Given the clear phylogenetic separations, that the threshold to discriminate species and subspecies is 70 and 79% dDDH, respectively, and that strains H1T and H3T differ physiologically and biochemically from their more closely related taxa, we propose to classify H1T and H3T into new taxa as follows: H3T as a new subspecies within the species P. akhurstii, and H1T as a new species within the Photorhabdus genus, in spite that H1T shares 70.6 % dDDH with P. akhurstii DSM 15138T, score that is slightly higher than the 70 % threshold that delimits species boundaries. The reason for this is that H1T and P. akhurstii DSM 15138T cluster apart in the phylogenetic trees and that dDDH scores between strain H1T and other P. akhurstii strains are lower than 70 %. Hence, the following names are proposed: Photorhabdus hindustanensis sp. nov. with the type strain H1T (=IARI-SGMG3T,=KCTC 82683T=CCM 9150T=CCOS 1975T) and P. akhurstii subsp. bharatensis subsp. nov. with the type strain H3T (=IARI-SGHR2T=KCTC 82684T=CCM 9149T=CCOS 1976T). These propositions automatically create P. akhurstii subsp. akhurstii subsp. nov. with DSM 15138T as the type strain (currently classified as P. akhurstii).
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Affiliation(s)
- Ricardo A R Machado
- Experimental Biology Research Group, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Vishal S Somvanshi
- Division of Nematology, Indian Council of Agricultural Research, Indian Agricultural Research Institute (ICAR-IARI), New Delhi, India
| | - Arthur Muller
- Experimental Biology Research Group, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Jyoti Kushwah
- Division of Nematology, Indian Council of Agricultural Research, Indian Agricultural Research Institute (ICAR-IARI), New Delhi, India
| | - Chaitra G Bhat
- Division of Nematology, Indian Council of Agricultural Research, Indian Agricultural Research Institute (ICAR-IARI), New Delhi, India
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Machado RAR, Muller A, Ghazal SM, Thanwisai A, Pagès S, Bode HB, Hussein MA, Khalil KM, Tisa LS. Photorhabdus heterorhabditis subsp. aluminescens subsp. nov., Photorhabdus heterorhabditis subsp. heterorhabditis subsp. nov., Photorhabdus australis subsp. thailandensis subsp. nov., Photorhabdus australis subsp. australis subsp. nov., and Photorhabdus aegyptia sp. nov. isolated from Heterorhabditis entomopathogenic nematodes. Int J Syst Evol Microbiol 2021; 71. [PMID: 33464198 DOI: 10.1099/ijsem.0.004610] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Three Gram-stain-negative, rod-shaped, non-spore-forming bacteria, BA1T, Q614T and PB68.1T, isolated from the digestive system of Heterorhabditis entomopathogenic nematodes, were biochemically and molecularly characterized to clarify their taxonomic affiliations. The 16S rRNA gene sequences of these strains suggest that they belong to the Gammaproteobacteria, to the family Morganellacea, and to the genus Photorhabdus. Deeper analyses using whole genome-based phylogenetic reconstructions suggest that BA1T is closely related to Photorhabdus akhursti, that Q614T is closely related to Photorhabdus heterorhabditis, and that PB68.1T is closely related to Photorhabdus australis. In silico genomic comparisons confirm these observations: BA1T and P. akhursti 15138T share 68.8 % digital DNA-DNA hybridization (dDDH), Q614T and P. heterorhabditis SF41T share 75.4 % dDDH, and PB68.1T and P. australis DSM 17609T share 76.6 % dDDH. Physiological and biochemical characterizations reveal that these three strains also differ from all validly described Photorhabdus species and from their more closely related taxa, contrary to what was previously suggested. We therefore propose to classify BA1T as a new species within the genus Photorhabdus, Q614T as a new subspecies within P. heterorhabditis, and PB68.1T as a new subspecies within P. australis. Hence, the following names are proposed for these strains: Photorhabdus aegyptia sp. nov. with the type strain BA1T(=DSM 111180T=CCOS 1943T=LMG 31957T), Photorhabdus heterorhabditis subsp. aluminescens subsp. nov. with the type strain Q614T (=DSM 111144T=CCOS 1944T=LMG 31959T) and Photorhabdus australis subsp. thailandensis subsp. nov. with the type strain PB68.1T (=DSM 111145T=CCOS 1942T). These propositions automatically create Photorhabdus heterorhabditis subsp. heterorhabditis subsp. nov. with SF41T as the type strain (currently classified as P. heterorhabditis) and Photorhabdus australis subsp. australis subsp. nov. with DSM17609T as the type strain (currently classified as P. australis).
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Affiliation(s)
- Ricardo A R Machado
- 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
| | - Shimaa M Ghazal
- Genetics and Cytology Department, Genetic Engineering and Biotechnology Division, National Research Center, Cairo, Egypt.,Department of Biological Sciences, University of New Hampshire, Durham, New Hampshire, USA
| | - Aunchalee Thanwisai
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand
| | - Sylvie Pagès
- INRAe, Université de Montpellier, UMR1333-DGIMI, 34095 Montpellier Cedex 05, France
| | - Helge B Bode
- Molekulare Biotechnologie, Fachbereich Biowissenschaften & Buchmann Institute for Molecular Life Sciences (BMLS), Goethe-Universität Frankfurt am Main & Senckenberg Gesellschaft für Naturforschung, Frankfurt, Germany
| | - Mona A Hussein
- Department of Pests and Plant Protection, Agricultural and Biological Division, National Research Centre, Dokki, Cairo, Egypt
| | - Kamal M Khalil
- Genetics and Cytology Department, Genetic Engineering and Biotechnology Division, National Research Center, Cairo, Egypt
| | - Louis S Tisa
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA
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5
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Sajnaga E, Kazimierczak W. Evolution and taxonomy of nematode-associated entomopathogenic bacteria of the genera Xenorhabdus and Photorhabdus: an overview. Symbiosis 2020. [DOI: 10.1007/s13199-019-00660-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
AbstractEntomopathogenic bacteria from the genera Photorhabdus and Xenorhabdus are closely related Gram-negative bacilli from the family Enterobacteriaceae (γ-Proteobacteria). They establish obligate mutualistic associations with soil nematodes from the genera Steinernema and Heterorhabditis to facilitate insect pathogenesis. The research of these two bacterial genera is focused mainly on their unique interactions with two different animal hosts, i.e. nematodes and insects. So far, studies of the mutualistic bacteria of nematodes collected from around the world have contributed to an increase in the number of the described Xenorhabdus and Photorhabdus species. Recently, the classification system of entomopatogenic nematode microsymbionts has undergone profound revision and now 26 species of the genus Xenorhabdus and 19 species of the genus Photorhabdus have been identified. Despite their similar life style and close phylogenetic origin, Photorhabdus and Xenorhabdus bacterial species differ significantly in e.g. the nematode host range, symbiotic strategies for parasite success, and arrays of released antibiotics and insecticidal toxins. As the knowledge of the diversity of entomopathogenic nematode microsymbionts helps to enable the use thereof, assessment of the phylogenetic relationships of these astounding bacterial genera is now a major challenge for researchers. The present article summarizes the main information on the taxonomy and evolutionary history of Xenorhabdus and Photorhabdus, entomopathogenic nematode symbionts.
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6
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Machado RAR, Bruno P, Arce CCM, Liechti N, Köhler A, Bernal J, Bruggmann R, Turlings TCJ. Photorhabdus khanii subsp. guanajuatensis subsp. nov., isolated from Heterorhabditis atacamensis, and Photorhabdus luminescens subsp. mexicana subsp. nov., isolated from Heterorhabditis mexicana entomopathogenic nematodes. Int J Syst Evol Microbiol 2019; 69:652-661. [PMID: 30688647 DOI: 10.1099/ijsem.0.003154] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two Gram-negative, rod-shaped, non-spore-forming bacteria, MEX20-17T and MEX47-22T, were isolated from the digestive system of Heterorhabditis atacamensis and Heterorhabditis mexicana entomopathogenic nematodes, respectively. Their 16S rRNA gene sequences suggest that strains MEX20-17T and MEX47-22T belong to the γ-Proteobacteria and to the genus Photorhabdus. Deeper analyses using housekeeping-gene-based and whole-genome-based phylogenetic reconstruction suggest that MEX20-17T is closely related to Photorhabdus khanii and that MEX47-22T is closely related to Photorhabdus luminescens. Sequence similarity scores confirm these observations: MEX20-17T and P. khanii DSM 3369T share 98.9 % nucleotide sequence identity (NSI) of concatenated housekeeping genes, 70.4 % in silico DNA-DNA hybridization (isDDH) and 97 % orthologous average nucleotide identity (orthoANI); and MEX47-22T and P. luminescens ATCC 29999T share 98.9 % NSI, 70.6 % isDDH and 97 % orthoANI. Physiological characterization indicates that both strains differ from all validly described Photorhabdus species and from their more closely related taxa. We therefore propose to classify MEX20-17T and MEXT47-22T as new subspecies within P. khanii and P. luminescens, respectively. Hence, the following names are proposed for these strains: Photorhabdus khanii subsp. guanajuatensis subsp. nov. with the type strain MEX20-17T (=LMG 30372T=CCOS 1191T) and Photorhabdus luminescenssubsp. mexicana subsp. nov. with the type strain MEX47-22T (=LMG 30528T=CCOS 1199T). These propositions automatically create Photorhabdus khanii subsp. khanii subsp. nov. with DSM 3369T as the type strain (currently classified as P. khanii), and Photorhabdus luminescenssubsp. luminescenssubsp. nov. with ATCC 29999T as the type strain (currently classified as P. luminescens).
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Affiliation(s)
| | - Pamela Bruno
- 2Laboratory of Fundamental and Applied Research in Chemical Ecology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Carla C M Arce
- 2Laboratory of Fundamental and Applied Research in Chemical Ecology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Nicole Liechti
- 3Interfaculty Bioinformatics Unit, University of Bern, Bern, Switzerland
| | - Angela Köhler
- 2Laboratory of Fundamental and Applied Research in Chemical Ecology, University of Neuchâtel, Neuchâtel, Switzerland
- 4Leibniz-Institut für Naturstoff-Forschung und Infektionsbiologie, Jena, Germany
| | - Julio Bernal
- 5Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - Rémy Bruggmann
- 2Laboratory of Fundamental and Applied Research in Chemical Ecology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Ted C J Turlings
- 2Laboratory of Fundamental and Applied Research in Chemical Ecology, University of Neuchâtel, Neuchâtel, Switzerland
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Whole-genome-based revisit of Photorhabdus phylogeny: proposal for the elevation of most Photorhabdus subspecies to the species level and description of one novel species Photorhabdus bodei sp. nov., and one novel subspecies Photorhabdus laumondii subsp. clarkei subsp. nov. Int J Syst Evol Microbiol 2018; 68:2664-2681. [DOI: 10.1099/ijsem.0.002820] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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8
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Kazimierczak W, Skrzypek H, Sajnaga E, Skowronek M, Waśko A, Kreft A. Strains of Photorhabdus spp. associated with polish Heterorhabditis isolates: their molecular and phenotypic characterization and symbiont exchange. Arch Microbiol 2017; 199:979-989. [PMID: 28382473 DOI: 10.1007/s00203-017-1368-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/10/2017] [Accepted: 03/15/2017] [Indexed: 12/24/2022]
Abstract
The relationships between six bacterial symbionts of the entomopathogenic nematodes Heterorhabditis bacteriophora and Heterorhabditis megidis from Poland to species and subspecies of the genus Photorhabdus were evaluated. This study was based on phylogenetic analysis of sequence data of five genes: 16S rRNA, gyrB, recA, gltX, and dnaN. The bacteria were also characterized phenotypically by biochemical and physiological tests. Our results have revealed that the Photorhabdus strains isolated from H. megidis belong to P. temperata, subsp. temperata and subsp. cinerea. Isolates from H. bacteriophora represent P. luminescens subs. kayaii and P. temperata subs. cinerea. This study for the first time provides evidence for H. bacteriophora and P. temperata subsp. cinerea symbiotic association. In addition, we tested whether the microsymbionts of the Polish H. bacteriophora and H. megidis isolates support the development of non-native nematode host population and colonization of their infective juveniles. It has been shown that the studied Photorhabdus strains can readily swap their nematode host, both at intra- and interspecies level. It supports the hypothesis of different symbiotic associations in the Heterorhabditis-Photorhabdus lineage.
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Affiliation(s)
- Waldemar Kazimierczak
- Laboratory of Biocontrol, Application and Production of EPN, Department of Biotechnology and Environmental Sciences, Centre for Interdisciplinary Research, John Paul II Catholic University of Lublin, ul. Konstantynów 1J, 20-708, Lublin, Poland.
| | - Henryk Skrzypek
- Laboratory of Ultrastructure and Electron Microscopy, Department of Biotechnology and Environmental Sciences, John Paul II Catholic University of Lublin, ul. Konstantynów 1F, 20-708, Lublin, Poland
| | - Ewa Sajnaga
- Laboratory of Biocontrol, Application and Production of EPN, Department of Biotechnology and Environmental Sciences, Centre for Interdisciplinary Research, John Paul II Catholic University of Lublin, ul. Konstantynów 1J, 20-708, Lublin, Poland
| | - Marcin Skowronek
- Laboratory of Biocontrol, Application and Production of EPN, Department of Biotechnology and Environmental Sciences, Centre for Interdisciplinary Research, John Paul II Catholic University of Lublin, ul. Konstantynów 1J, 20-708, Lublin, Poland
| | - Adam Waśko
- Department of Biotechnology, Human Nutrition and Science of Food Commodities, University of Life Sciences in Lublin, ul. Skromna 8, 20-704, Lublin, Poland
| | - Anna Kreft
- Laboratory of Biocontrol, Application and Production of EPN, Department of Biotechnology and Environmental Sciences, Centre for Interdisciplinary Research, John Paul II Catholic University of Lublin, ul. Konstantynów 1J, 20-708, Lublin, Poland
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9
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Molecular and phenotypic characterization of Xenorhabdus bovienii symbiotically associated with Steinernema silvaticum. Arch Microbiol 2016; 198:995-1003. [PMID: 27342112 DOI: 10.1007/s00203-016-1261-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/13/2016] [Accepted: 06/15/2016] [Indexed: 10/21/2022]
Abstract
Steinernema silvaticum is a common entomopathogenic nematode in soil of Europe; however, little is known about the bacteria living in symbiosis with this animal. In this study, we have isolated four bacterial strains from S. silvaticum and identified them as members of the species Xenorhabdus bovienii. This study was based on 16S rRNA and concatenated recA, dnaN, gltX, and gyrB gene sequence analysis. In addition, phenotypic traits have been considered, indicating that the tested strains are the most similar to those of X. bovienii. The phylogenetic relationships between the isolated strains and other strains of X. bovienii derived from various nematode hosts were analyzed and discussed. This is the first report confirming the symbiotic association of X. bovienii with S. silvaticum.
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10
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Ferreira T, van Reenen C, Pagès S, Tailliez P, Malan AP, Dicks LMT. Photorhabdus luminescens subsp. noenieputensis subsp. nov., a symbiotic bacterium associated with a novel Heterorhabditis species related to Heterorhabditis indica. Int J Syst Evol Microbiol 2013; 63:1853-1858. [DOI: 10.1099/ijs.0.044388-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The bacterial symbiont AM7T, isolated from a novel entomopathogenic nematode species of the genus Heterorhabditis, displays the main phenotypic traits of the genus
Photorhabdus
and is highly pathogenic to Galleria mellonella. Phylogenetic analysis based on a multigene approach (16S rRNA, recA, gyrB, dnaN, gltX and infB) confirmed the classification of isolate AM7T within the species
Photorhabdus luminescens
and revealed its close relatedness to
Photorhabdus luminescens subsp. caribbeanensis
,
P. luminescens subsp. akhurstii
and
P. luminescens subsp. hainanensis
. The five concatenated protein-encoding sequences (4197 nt) of strain AM7T revealed 95.8, 95.4 and 94.9 % nucleotide identity to sequences of
P. luminescens subsp. caribbeanensis
HG29T,
P. luminescens subsp. akhurstii
FRG04T and
P. luminescens subsp. hainanensis
C8404T, respectively. These identity values are less than the threshold of 97 % proposed for classification within one of the existing subspecies of
P. luminescens
. Unlike other strains described for
P. luminescens
, strain AM7T produces acid from adonitol, sorbitol and xylitol, assimilates xylitol and has no lipase activity on medium containing Tween 20 or 60. Strain AM7T is differentiated from
P. luminescens subsp. caribbeanensis
by the assimilation of N-acetylglucosamine and the absence of haemolytic activity. Unlike
P. luminescens subsp. akhurstii
, strain AM7T does not assimilate mannitol, and it is distinguished from
P. luminescens subsp. hainanensis
by the assimilation of trehalose and citrate, the inability to produce indole from tryptophan and the presence of acetoin production and urease activity. Strain AM7T ( = ATCC BAA-2407T = DSM 25462T) belongs to a novel subspecies, and is proposed as the type strain of Photorhabdus luminescens subsp. noenieputensis sp. nov.
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Affiliation(s)
- Tiarin Ferreira
- Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, 7602 Matieland, South Africa
| | - Carol van Reenen
- Department of Microbiology, Stellenbosch University, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa
| | - Sylvie Pagès
- Université Montpellier 2, UMR1333 Diversité, Génomes & Interactions Microorganismes-Insectes (DGIMI), F-34000 Montpellier, France
- INRA, UMR1333 Diversité, Génomes & Interactions Microorganismes-Insectes (DGIMI), F-34000 Montpellier, France
| | - Patrick Tailliez
- Université Montpellier 2, UMR1333 Diversité, Génomes & Interactions Microorganismes-Insectes (DGIMI), F-34000 Montpellier, France
- INRA, UMR1333 Diversité, Génomes & Interactions Microorganismes-Insectes (DGIMI), F-34000 Montpellier, France
| | - Antoinette P. Malan
- Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, 7602 Matieland, South Africa
| | - Leon M. T. Dicks
- Department of Microbiology, Stellenbosch University, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa
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11
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Schwartz HT, Antoshechkin I, Sternberg PW. Applications of high-throughput sequencing to symbiotic nematodes of the genus Heterorhabditis. Symbiosis 2012. [DOI: 10.1007/s13199-012-0151-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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12
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Peat SM, ffrench-Constant RH, Waterfield NR, Marokházi J, Fodor A, Adams BJ. A robust phylogenetic framework for the bacterial genus Photorhabdus and its use in studying the evolution and maintenance of bioluminescence: A case for 16S, gyrB, and glnA. Mol Phylogenet Evol 2010; 57:728-40. [DOI: 10.1016/j.ympev.2010.08.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 08/11/2010] [Accepted: 08/12/2010] [Indexed: 10/19/2022]
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13
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Photorhabdus luminescens subsp. kleinii subsp. nov. (Enterobacteriales: Enterobacteriaceae). Curr Microbiol 2010; 62:539-43. [DOI: 10.1007/s00284-010-9741-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 07/28/2010] [Indexed: 11/30/2022]
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14
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Photorhabdus temperata subsp. stackebrandtii subsp. nov. (Enterobacteriales: Enterobacteriaceae). Curr Microbiol 2010; 61:291-7. [DOI: 10.1007/s00284-010-9610-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Accepted: 02/05/2010] [Indexed: 10/19/2022]
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15
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Tailliez P, Laroui C, Ginibre N, Paule A, Pagès S, Boemare N. Phylogeny of Photorhabdus and Xenorhabdus based on universally conserved protein-coding sequences and implications for the taxonomy of these two genera. Proposal of new taxa: X. vietnamensis sp. nov., P. luminescens subsp. caribbeanensis subsp. nov., P. luminescens subsp. hainanensis subsp. nov., P. temperata subsp. khanii subsp. nov., P. temperata subsp. tasmaniensis subsp. nov., and the reclassification of P. luminescens subsp. thracensis as P. temperata subsp. thracensis comb. nov. Int J Syst Evol Microbiol 2009; 60:1921-1937. [PMID: 19783607 DOI: 10.1099/ijs.0.014308-0] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We used the information from a set of concatenated sequences from four genes (recA, gyrB, dnaN and gltX) to investigate the phylogeny of the genera Photorhabdus and Xenorhabdus (entomopathogenic bacteria associated with nematodes of the genera Heterorhabditis and Steinernema, respectively). The robustness of the phylogenetic tree obtained by this multigene approach was significantly better than that of the tree obtained by a single gene approach. The comparison of the topologies of single gene phylogenetic trees highlighted discrepancies which have implications for the classification of strains and new isolates; in particular, we propose the transfer of Photorhabdus luminescens subsp. thracensis to Photorhabdus temperata subsp. thracensis comb. nov. (type strain CIP 108426T =DSM 15199T). We found that, within the genus Xenorhabdus, strains or isolates that shared less than 97 % nucleotide identity (NI), calculated on the concatenated sequences of the four gene fragments (recA, gyrB, dnaN and gltX) encompassing 3395 nucleotides, did not belong to the same species. Thus, at the 97% NI cutoff, we confirm the current 20 species of the genus Xenorhabdus and propose the description of a novel species, Xenorhabdus vietnamensis sp. nov. (type strain VN01T =CIP 109945T =DSM 22392T). Within each of the three current species of the genus Photorhabdus, P. asymbiotica, P. luminescens and P. temperata, strains or isolates which shared less than 97% NI did not belong to the same subspecies. Comparisons of the four gene fragments plus the rplB gene fragment analysed separately led us to propose four novel subspecies: Photorhabdus luminescens subsp. caribbeanensis subsp. nov. (type strain HG29T =CIP 109949T =DSM 22391T), P. luminescens subsp. hainanensis subsp. nov. (type strain C8404T = CIP 109946T =DSM 22397T), P. temperata subsp. khanii subsp. nov. (type strain C1T =NC19(T) =CIP 109947T =DSM 3369T), and P. temperata subsp. tasmaniensis subsp. nov. (type strain T327T =CIP 109948T =DSM 22387T).
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Affiliation(s)
- Patrick Tailliez
- INRA and Université Montpellier 2, Unité d'Ecologie Microbienne des Insectes and Interactions hôte-Pathogène, F-34000 Montpellier, France
| | - Christine Laroui
- INRA and Université Montpellier 2, Unité d'Ecologie Microbienne des Insectes and Interactions hôte-Pathogène, F-34000 Montpellier, France
| | - Nadège Ginibre
- INRA and Université Montpellier 2, Unité d'Ecologie Microbienne des Insectes and Interactions hôte-Pathogène, F-34000 Montpellier, France
| | - Armelle Paule
- INRA and Université Montpellier 2, Unité d'Ecologie Microbienne des Insectes and Interactions hôte-Pathogène, F-34000 Montpellier, France
| | - Sylvie Pagès
- INRA and Université Montpellier 2, Unité d'Ecologie Microbienne des Insectes and Interactions hôte-Pathogène, F-34000 Montpellier, France
| | - Noël Boemare
- INRA and Université Montpellier 2, Unité d'Ecologie Microbienne des Insectes and Interactions hôte-Pathogène, F-34000 Montpellier, France
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16
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Tsai MH, Tang LC, Hou RF. The bacterium associated with the entomopathogenic nematode Steinernema abbasi (Nematoda: Steinernematidae) isolated from Taiwan. J Invertebr Pathol 2008; 99:242-5. [PMID: 18486948 DOI: 10.1016/j.jip.2008.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 04/05/2008] [Accepted: 04/09/2008] [Indexed: 10/22/2022]
Abstract
A symbiotic bacterium of the entomopathogenic nematode, Steinernema abbasi, isolated from Taiwan, determined to be a species of Xenorhabdus based on its physiological and biochemical characteristics has been determined to be similar to Xenorhabdus indica of S. abbasi Oman isolate as based on sequence analyses of 16S rDNA.
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Affiliation(s)
- Mi-Hau Tsai
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan 402, ROC
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17
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Tailliez P, Pagès S, Ginibre N, Boemare N. New insight into diversity in the genus Xenorhabdus, including the description of ten novel species. Int J Syst Evol Microbiol 2007; 56:2805-2818. [PMID: 17158981 DOI: 10.1099/ijs.0.64287-0] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We investigated the diversity of a collection of 76 Xenorhabdus strains, isolated from at least 27 species of Steinernema nematodes and collected in 32 countries, using three complementary approaches: 16S rRNA gene sequencing, molecular typing and phenotypic characterization. The 16S rRNA gene sequences of the Xenorhabdus strains were highly conserved (similarity coefficient >95 %), suggesting that the common ancestor of the genus probably emerged between 250 and 500 million years ago. Based on comparisons of the 16S rRNA gene sequences, we identified 13 groups and seven unique sequences. This classification was confirmed by analysis of molecular typing profiles of the strains, leading to the classification of new isolates into the Xenorhabdus species described previously and the description of ten novel Xenorhabdus species: Xenorhabdus cabanillasii sp. nov. (type strain USTX62(T)=CIP 109066(T)=DSM 17905(T)), Xenorhabdus doucetiae sp. nov. (type strain FRM16(T)=CIP 109074(T)=DSM 17909(T)), Xenorhabdus griffiniae sp. nov. (type strain ID10(T)=CIP 109073(T)=DSM 17911(T)), Xenorhabdus hominickii sp. nov. (type strain KE01(T)=CIP 109072(T)=DSM 17903(T)), Xenorhabdus koppenhoeferi sp. nov. (type strain USNJ01(T)=CIP 109199(T)=DSM 18168(T)), Xenorhabdus kozodoii sp. nov. (type strain SaV(T)=CIP 109068(T)=DSM 17907(T)), Xenorhabdus mauleonii sp. nov. (type strain VC01(T)=CIP 109075(T)=DSM 17908(T)), Xenorhabdus miraniensis sp. nov. (type strain Q1(T)=CIP 109069(T)=DSM 17902(T)), Xenorhabdus romanii sp. nov. (type strain PR06-A(T)=CIP 109070(T)=DSM 17910(T)) and Xenorhabdus stockiae sp. nov. (type strain TH01(T)=CIP 109067(T)=DSM 17904(T)). The Xenorhabdus strains studied here had very similar phenotypic patterns, but phenotypic features nonetheless differentiated the following species: X. bovienii, X. cabanillasii, X. hominickii, X. kozodoii, X. nematophila, X. poinarii and X. szentirmaii. Based on phenotypic analysis, we identified two major groups of strains. Phenotypic group G(A) comprised strains able to grow at temperatures of 35-42 degrees C, whereas phenotypic group G(B) comprised strains that grew at temperatures below 35 degrees C, suggesting that some Xenorhabdus species may be adapted to tropical or temperate regions and/or influenced by the growth and development temperature of their nematode host.
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Affiliation(s)
- Patrick Tailliez
- Institut National de la Recherche Agronomique, Unité d'Ecologie Microbienne des Insectes et Interactions hôte-Pathogène, Université Montpellier II, Place Eugène Bataillon, Case courrier 54, Bâtiment 24, 34095 Montpellier CEDEX 5, France
| | - Sylvie Pagès
- Institut National de la Recherche Agronomique, Unité d'Ecologie Microbienne des Insectes et Interactions hôte-Pathogène, Université Montpellier II, Place Eugène Bataillon, Case courrier 54, Bâtiment 24, 34095 Montpellier CEDEX 5, France
| | - Nadège Ginibre
- Institut National de la Recherche Agronomique, Unité d'Ecologie Microbienne des Insectes et Interactions hôte-Pathogène, Université Montpellier II, Place Eugène Bataillon, Case courrier 54, Bâtiment 24, 34095 Montpellier CEDEX 5, France
| | - Noël Boemare
- Institut National de la Recherche Agronomique, Unité d'Ecologie Microbienne des Insectes et Interactions hôte-Pathogène, Université Montpellier II, Place Eugène Bataillon, Case courrier 54, Bâtiment 24, 34095 Montpellier CEDEX 5, France
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18
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Gaudriault S, Duchaud E, Lanois A, Canoy AS, Bourot S, Derose R, Kunst F, Boemare N, Givaudan A. Whole-genome comparison between Photorhabdus strains to identify genomic regions involved in the specificity of nematode interaction. J Bacteriol 2006; 188:809-14. [PMID: 16385072 PMCID: PMC1347316 DOI: 10.1128/jb.188.2.809-814.2006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bacterium Photorhabdus establishes a highly specific association with Heterorhabditis, its nematode host. Photorhabdus strains associated with Heterorhabditis bacteriophora or Heterorhabditis megidis were compared using a Photorhabdus DNA microarray. We describe 31 regions belonging to the Photorhabdus flexible gene pool. Distribution analysis of regions among the Photorhabdus genus identified loci possibly involved in nematode specificity.
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Affiliation(s)
- S Gaudriault
- Laboratoire EMIP Ecologie Microbienne des Insectes et Interaction Hôtes-Pathogène, Université Montpellier II, UMR1133 INRA-UMII, 34095 Montpellier Cedex 5, France.
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19
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Akhurst RJ, Boemare NE, Janssen PH, Peel MM, Alfredson DA, Beard CE. Taxonomy of Australian clinical isolates of the genus Photorhabdus and proposal of Photorhabdus asymbiotica subsp. asymbiotica subsp. nov. and P. asymbiotica subsp. australis subsp. nov. Int J Syst Evol Microbiol 2005; 54:1301-1310. [PMID: 15280306 DOI: 10.1099/ijs.0.03005-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The relationship of Photorhabdus isolates that were cultured from human clinical specimens in Australia to Photorhabdus asymbiotica isolates from human clinical specimens in the USA and to species of the genus Photorhabdus that are associated symbiotically with entomopathogenic nematodes was evaluated. A polyphasic approach that involved DNA-DNA hybridization, phylogenetic analyses of 16S rRNA and gyrB gene sequences and phenotypic characterization was adopted. These investigations showed that gyrB gene sequence data correlated well with DNA-DNA hybridization and phenotypic data, but that 16S rRNA gene sequence data were not suitable for defining species within the genus Photorhabdus. Australian clinical isolates proved to be related most closely to clinical isolates from the USA, but the two groups were distinct. A novel subspecies, Photorhabdus asymbiotica subsp. australis subsp. nov. (type strain, 9802892T=CIP 108025T=ACM 5210T), is proposed, with the concomitant creation of Photorhabdus asymbiotica subsp. asymbiotica subsp. nov. Analysis of gyrB sequences, coupled with previously published data on DNA-DNA hybridization and PCR-RFLP analysis of the 16S rRNA gene, indicated that there are more than the three subspecies of Photorhabdus luminescens that have been described and confirmed the validity of the previously proposed subdivision of Photorhabdus temperata. Although a non-luminescent, symbiotic isolate clustered consistently with P. asymbiotica in gyrB phylogenetic analyses, DNA-DNA hybridization indicated that this isolate does not belong to the species P. asymbiotica and that there is a clear distinction between symbiotic and clinical species of Photorhabdus.
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Affiliation(s)
- R J Akhurst
- Division of Entomology, Commonwealth Scientific and Industrial Research Organization, Canberra ACT 2601, Australia
| | - N E Boemare
- Ecologie microbienne des Insectes et Interaction Hôte-pathogène Unité EMIP INRA 1133, Université Montpellier II, 34095 Montpellier CEDEX 5, France
| | - P H Janssen
- Department of Microbiology and Immunology, University of Melbourne, Vic. 3010, Australia
| | - M M Peel
- Department of Microbiology and Immunology, University of Melbourne, Vic. 3010, Australia
| | | | - C E Beard
- Division of Entomology, Commonwealth Scientific and Industrial Research Organization, Canberra ACT 2601, Australia
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20
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Ciche TA, Blackburn M, Carney JR, Ensign JC. Photobactin: a catechol siderophore produced by Photorhabdus luminescens, an entomopathogen mutually associated with Heterorhabditis bacteriophora NC1 nematodes. Appl Environ Microbiol 2003; 69:4706-13. [PMID: 12902261 PMCID: PMC169088 DOI: 10.1128/aem.69.8.4706-4713.2003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nematode Heterorhabditis bacteriophora transmits a monoculture of Photorhabdus luminescens bacteria to insect hosts, where it requires the bacteria for efficient insect pathogenicity and as a substrate for growth and reproduction. Siderophore production was implicated as being involved in the symbiosis because an ngrA mutant inadequate for supporting nematode growth and reproduction was also deficient in producing siderophore activity and ngrA is homologous to a siderophore biosynthetic gene, entD. The role of the siderophore in the symbiosis with the nematode was determined by isolating and characterizing a mini-Tn5-induced mutant, NS414, producing no detectable siderophore activity. This mutant, being defective for growth in iron-depleted medium, was normal in supporting nematode growth and reproduction, in transmission by the dauer juvenile nematode, and in insect pathogenicity. The mini-Tn5 transposon was inserted into phbH; whose protein product is a putative peptidyl carrier protein homologous to the nonribosomal peptide synthetase VibF of Vibrio cholerae. Other putative siderophore biosynthetic and transport genes flanking phbH were characterized. The catecholate siderophore was purified, its structure was determined to be 2-(2,3-dihydroxyphenyl)-5-methyl-4,5-dihydro-oxazole-4-carboxylic acid [4-(2,3-dihydroxybenzoylamino)-butyl]-amide, and it was given the generic name photobactin. Antibiotic activity was detected with purified photobactin, indicating that the siderophore may contribute to antibiosis of the insect cadaver. These results eliminate the lack of siderophore activity as the cause for the inadequacy of the ngrA mutant in supporting nematode growth and reproduction.
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Affiliation(s)
- Todd A Ciche
- Department of Bacteriology, University of Wisconsin, Madison, Wisconsin 53706, USA.
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21
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ffrench-Constant R, Waterfield N, Daborn P, Joyce S, Bennett H, Au C, Dowling A, Boundy S, Reynolds S, Clarke D. Photorhabdus: towards a functional genomic analysis of a symbiont and pathogen. FEMS Microbiol Rev 2003; 26:433-56. [PMID: 12586390 DOI: 10.1111/j.1574-6976.2003.tb00625.x] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Pathogenicity and symbiosis are central to bacteria-host interactions. Although several human pathogens have been subjected to functional genomic analysis, we still understand little about bacteria-invertebrate interactions despite their ecological prevalence. Advances in our knowledge of this area are often hindered by the difficulty of isolating and working with invertebrate pathogenic bacteria and their hosts. Here we review studies on pathogenicity and symbiosis in an insect pathogenic bacterium Photorhabdus and its entomopathogenic nematode vector and model insect hosts. Whilst switching between these hosts, Photorhabdus changes from a state of symbiosis with its nematode vector to one of pathogenicity towards its new insect host and both the bacteria and the nematode then cooperatively exploit the dying insect. We examine candidate genes involved in symbiosis and pathogenicity, their secretion and expression patterns in culture and in the host, and begin to dissect the extent of their genetic coregulation. We describe the presence of several large genomic islands, putatively involved in pathogenicity or symbiosis, within the otherwise Yersinia-like backbone of the Photorhabdus genome. Finally, we examine the emerging comparative genomics of the Photorhabdus group and begin to describe the interrelationship between anti-invertebrate virulence factors and those used against vertebrates.
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Affiliation(s)
- Richard ffrench-Constant
- Centre for Molecular Microbiology, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
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22
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Brillard J, Duchaud E, Boemare N, Kunst F, Givaudan A. The PhlA hemolysin from the entomopathogenic bacterium Photorhabdus luminescens belongs to the two-partner secretion family of hemolysins. J Bacteriol 2002; 184:3871-8. [PMID: 12081958 PMCID: PMC135187 DOI: 10.1128/jb.184.14.3871-3878.2002] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Photorhabdus is an entomopathogenic bacterium symbiotically associated with nematodes of the family Heterorhabditidae. Bacterial hemolysins found in numerous pathogenic bacteria are often virulence factors. We describe here the nucleotide sequence and the molecular characterization of the Photorhabdus luminescens phlBA operon, a locus encoding a hemolysin which shows similarities to the Serratia type of hemolysins. It belongs to the two-partner secretion (TPS) family of proteins. In low-iron conditions, a transcriptional induction of the phlBA operon was observed by using the chloramphenicol acetyltransferase reporter gene, causing an increase in PhlA hemolytic activity compared to iron-rich media. A spontaneous phase variant of P. luminescens was deregulated in phlBA transcription. The phlA mutant constructed by allelic exchange remained highly pathogenic after injection in the lepidopteran Spodoptera littoralis, indicating that PhlA hemolysin is not a major virulence determinant. Using the gene encoding green fluorescent protein as a reporter, phlBA transcription was observed in hemolymph before insect death. We therefore discuss the possible role of PhlA hemolytic activity in the bacterium-nematode-insect interactions.
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Affiliation(s)
- Julien Brillard
- Laboratoire EMIP, Université Montpellier II, IFR56, Institut National de la Recherche Agronomique (UMR 1133), 34095 Montpellier Cedex 5, Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Eric Duchaud
- Laboratoire EMIP, Université Montpellier II, IFR56, Institut National de la Recherche Agronomique (UMR 1133), 34095 Montpellier Cedex 5, Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Noël Boemare
- Laboratoire EMIP, Université Montpellier II, IFR56, Institut National de la Recherche Agronomique (UMR 1133), 34095 Montpellier Cedex 5, Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Frank Kunst
- Laboratoire EMIP, Université Montpellier II, IFR56, Institut National de la Recherche Agronomique (UMR 1133), 34095 Montpellier Cedex 5, Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Alain Givaudan
- Laboratoire EMIP, Université Montpellier II, IFR56, Institut National de la Recherche Agronomique (UMR 1133), 34095 Montpellier Cedex 5, Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 75724 Paris Cedex 15, France
- Corresponding author. Mailing address: Laboratoire EMIP, CC101, INRA-Université Montpellier II (UMR 1133), Place E. Bataillon, 34095 Montpellier Cedex 5, France. Phone: 33-4-67144812. Fax: 33-4-67144679. E-mail:
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23
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Brillard J, Ribeiro C, Boemare N, Brehélin M, Givaudan A. Two distinct hemolytic activities in Xenorhabdus nematophila are active against immunocompetent insect cells. Appl Environ Microbiol 2001; 67:2515-25. [PMID: 11375158 PMCID: PMC92902 DOI: 10.1128/aem.67.6.2515-2525.2001] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Xenorhabdus spp. and Photorhabdus spp. are major insect bacterial pathogens symbiotically associated with nematodes. These bacteria are transported by their nematode hosts into the hemocoel of the insect prey, where they proliferate within hemolymph. In this work we report that wild strains belonging to different species of both genera are able to produce hemolysin activity on blood agar plates. Using a hemocyte monolayer bioassay, cytolytic activity against immunocompetent cells from the hemolymph of Spodoptera littoralis (Lepidoptera: Noctuidae) was found only in supernatants of Xenorhabdus; none was detected in supernatants of various strains of Photorhabdus. During in vitro bacterial growth of Xenorhabdus nematophila F1, two successive bursts of cytolytic activity were detected. The first extracellular cytolytic activity occurred when bacterial cells reached the stationary phase. It also displayed a hemolytic activity on sheep red blood cells, and it was heat labile. Among insect hemocyte types, granulocytes were the preferred target. Lysis of hemocytes by necrosis was preceded by a dramatic vacuolization of the cells. In contrast the second burst of cytolytic activity occurred late during stationary phase and caused hemolysis of rabbit red blood cells, and insect plasmatocytes were the preferred target. This second activity is heat resistant and produced shrinkage and necrosis of hemocytes. Insertional inactivation of flhD gene in X. nematophila leads to the loss of hemolysis activity on sheep red blood cells and an attenuated virulence phenotype in S. littoralis (A. Givaudan and A. Lanois, J. Bacteriol. 182:107-115, 2000). This mutant was unable to produce the early cytolytic activity, but it always displayed the late cytolytic effect, preferably active on plasmatocytes. Thus, X. nematophila produced two independent cytolytic activities against different insect cell targets known for their major role in cellular immunity.
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Affiliation(s)
- J Brillard
- Laboratoire EMIP, Université Montpellier II, IFR 56, Institut National de la Recherche Agronomique (UMR 1133), 34095 Montpellier Cedex 05, France
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24
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Han R, Ehlers RU. Effect of Photorhabdus luminescens phase variants on the in vivo and in vitro development and reproduction of the entomopathogenic nematodes Heterorhabditis bacteriophora and Steinernema carpocapsae. FEMS Microbiol Ecol 2001; 35:239-247. [PMID: 11311434 DOI: 10.1111/j.1574-6941.2001.tb00809.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Photorhabdus luminescens (Enterobacteriaceae) is a symbiont of entomopathogenic nematodes Heterorhabditis spp. (Nematoda: Rhabditida) used for biological control of insect pests. For industrial mass production, the nematodes are produced in liquid media, pre-incubated with their bacterial symbiont, which provides nutrients essential for the nematode's development and reproduction. Particularly under in vitro conditions, P. luminescens produces phase variants, which do not allow normal nematode development. The phase variants were distinguished based on dye absorption, pigmentation, production of antibiotic substances, occurrence of crystalline inclusion proteins and bioluminescence. To understand the significance of the phase shift for the symbiotic interaction between the bacterium and the nematode, feeding experiments tested the effect of homologous and heterologous P. luminescens phase variants isolated from a Chinese Heterorhabditis bacteriophora (HO6), the Heterorhabditis megidis type strain from Ohio (HNA) and the type strain of Heterorhabditis indica (LN2) on the in vivo and in vitro development and reproduction of the nematode species H. bacteriophora (strain HO6) and another rhabditid and entomopathogenic nematode, Steinernema carpocapsae (A24). In axenically cultured insect larvae (Galleria mellonella) and in vitro in liquid media, H. bacteriophora produced offspring on phase I of its homologous symbiont and on the heterologous symbiont of H. megidis, but not on the two corresponding phase II variants. In solid media, nematode yields were much lower on phase II than on phase I variants. On the heterologous phase I symbiont isolated from H. indica the development of H. bacteriophora was not beyond the fourth juvenile stage of the nematode in any of the media tested, but further progressed on phase II with even a small amount of offspring recorded in solid media. Infective juveniles of S. carpocapsae did not develop beyond the J3 stage on all phase I P. luminescens. They died in phase I P. luminescens isolated from H. bacteriophora. Development to adults was recorded for S. carpocapsae on all phase II symbionts and offspring were produced in all media except in liquid. It is concluded that a lack of essential nutrients or the production of toxins is not responsible for the negative impact of homologous phase II symbiont cells on the development and reproduction of H. bacteriophora. The infective juveniles of H. bacteriophora retained cells of the homologous phase I symbiont, but not phase II cells and cells from heterologous symbionts, indicating that the transmission of the symbiont by the infective juvenile is selective for phase I cells and the homologous bacterial associate.
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Affiliation(s)
- R Han
- Institute for Phytopathology, Department for Biotechnology and Biological Control, Christian-Albrechts-University Kiel, Klausdorfer Str. 28-36, 24223, Raisdorf, Germany
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Babic I, Fischer-Le Saux M, Giraud E, Boemare N. Occurrence of natural dixenic associations between the symbiont Photorhabdus luminescens and bacteria related to Ochrobactrum spp. in tropical entomopathogenic Heterorhabditis spp. (Nematoda, Rhabditida). MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 3):709-718. [PMID: 10746775 DOI: 10.1099/00221287-146-3-709] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bacteria naturally associated with the symbiont Photorhabdus luminescens subsp. akhurstii were isolated from the entomopathogenic nematode Heterorhabditis indica. Bacterial isolates distinct from P. luminescens subsp. akhurstii were obtained from 33% of the samples. Fourteen bacterial isolates, from nematodes collected from three different Caribbean islands, were characterized by conventional phenotypic tests, restriction fragment length polymorphism and sequence analyses of PCR-amplified 16S rRNA genes (16S rDNAs). Isolates were grouped into three genotypes, each one being associated with one Caribbean island. Phenotypic characteristics and 16S rDNA analysis showed that the Photorhabdus-associated bacteria were closely related to Ochrobactrum anthropi for the group from Guadeloupe, and to Ochrobactrum intermedium for the two groups from the Dominican Republic and Puerto Rico. No pathogenicity of the Ochrobactrum spp. to the insects Galleria mellonella and Spodoptera littoralis (Lepidoptera) was detected. Since Ochrobactrum spp. are considered as human opportunist pathogens, the mass production of entomopathogenic nematodes for biological control requires strict vigilance.
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Affiliation(s)
- Isabelle Babic
- Laboratoire de Pathologie Comparée, INRA-CNRS, IFR 56 'Biologie cellulaire et Processus infectieux', Université Montpellier II, CP 101, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France1
| | - Marion Fischer-Le Saux
- Laboratoire de Pathologie Comparée, INRA-CNRS, IFR 56 'Biologie cellulaire et Processus infectieux', Université Montpellier II, CP 101, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France1
| | - Eric Giraud
- Laboratoire des Symbioses Tropicales et Méditerranéennes, CIRAD-IRD-INRA-Agro-Montpellier, BP 5035, F-34032 Montpellier Cedex 1, France2
| | - Noël Boemare
- Laboratoire de Pathologie Comparée, INRA-CNRS, IFR 56 'Biologie cellulaire et Processus infectieux', Université Montpellier II, CP 101, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France1
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Givaudan A, Lanois A. flhDC, the flagellar master operon of Xenorhabdus nematophilus: requirement for motility, lipolysis, extracellular hemolysis, and full virulence in insects. J Bacteriol 2000; 182:107-15. [PMID: 10613869 PMCID: PMC94246 DOI: 10.1128/jb.182.1.107-115.2000] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Xenorhabdus is a major insect pathogen symbiotically associated with nematodes of the family Steinernematidae. This motile bacterium displays swarming behavior on suitable media, but a spontaneous loss of motility is observed as part of a phenomenon designated phase variation which involves the loss of stationary-phase products active as antibiotics and potential virulence factors. To investigate the role of one of the transcriptional activators of flagellar genes, FlhDC, in motility and virulence, the Xenorhabdus nematophilus flhDC locus was identified by functional complementation of an Escherichia coli flhD null mutant and DNA sequencing. Construction of X. nematophilus flhD null mutants confirmed that the flhDC operon controls flagellin expression but also revealed that lipolytic and extracellular hemolysin activity is flhDC dependent. We also showed that the flhD null mutant displayed a slightly attenuated virulence phenotype in Spodoptera littoralis compared to that of the wild-type strain. Thus, these data indicated that motility, lipase, hemolysin, or unknown functions controlled by the flhDC operon are involved in the infectious process in insects. Our investigation expands the view of the flagellar regulon as a checkpoint coupled to a major network involving bacterial physiological aspects as well as motility.
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Affiliation(s)
- A Givaudan
- Laboratoire de Pathologie Comparée, Université Montpellier II, Institut National de la Recherche Agronomique-Centre National de la Recherche Scientifique (URA 2209), France.
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Peel MM, Alfredson DA, Gerrard JG, Davis JM, Robson JM, McDougall RJ, Scullie BL, Akhurst RJ. Isolation, identification, and molecular characterization of strains of Photorhabdus luminescens from infected humans in Australia. J Clin Microbiol 1999; 37:3647-53. [PMID: 10523568 PMCID: PMC85716 DOI: 10.1128/jcm.37.11.3647-3653.1999] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We describe the isolation of Photorhabdus (Xenorhabdus) luminescens from four Australian patients: two with multiple skin lesions, one with bacteremia only, and one with disseminated infection. One of the patients had multiple skin lesions following the bite of a spider, while the lesions in the other patient were possibly associated with a spider bite. The source of infection for the remaining two patients is unknown. As a member of the family Enterobacteriaceae, P. luminescens is unusual in that it fails to reduce nitrate and ferments only glucose and mannose. It gives negative reactions for lysine decarboxylase, arginine dihydrolase, and ornithine decarboxylase (Moeller). The species is motile, utilizes citrate, hydrolyzes urea, and usually produces a unique type of annular hemolysis on sheep blood agar plates incubated at 25 degrees C. A weak bioluminescence is the defining characteristic. P. luminescens is an insect pathogen and is symbiotically associated with entomopathogenic nematodes. Its isolation from human clinical specimens has been reported previously from the United States. Restriction fragment length polymorphism-PCR analysis of the 16S rRNA gene demonstrated a high level of similarity among the Australian clinical strains and significant differences between the Australian clinical strains and the U.S. clinical strains. However, numerical analyses of the data suggest that the two groups of clinical strains are more similar to each other than they are to the symbiotic strains found in nematodes. This is the first report of the isolation of P. luminescens from infected humans in Australia and the second report of the isolation of this species from infected humans worldwide.
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Affiliation(s)
- M M Peel
- Microbiological Diagnostic Unit, The University of Melbourne, Parkville, Victoria 3052, Australia.
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Bonifassi E, Fischer-Le Saux M, Boemare N, Lanois A, Laumond C, Smart G. Gnotobiological study of infective juveniles and symbionts of Steinernema scapterisci: A model to clarify the concept of the natural occurrence of monoxenic associations in entomopathogenic nematodes. J Invertebr Pathol 1999; 74:164-72. [PMID: 10486229 DOI: 10.1006/jipa.1999.4866] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gnotobiology of Steinernema scapterisci and bacteriological study of its symbiont confirmed that this nematode harbors a symbiotic species of Xenorhabdus, as do other Steinermena species. Based on phenotypic and 16S rDNA data, this Xenorhabdus strain UY61 could be distinguished from other Xenorhabdus species. Bacteria reported previously as being associated with this nematode and belonging to several other genera were probably contaminating bacteria located in the intercuticular space of the infective juveniles (IJs). These bacteria were detrimental to nematode reproduction in Galleria mellonella. Axenic S. scapterisci and its symbiont Xenorhabdus strain UY61 alone were not pathogenic to G. mellonella. The combination of both partners reestablished the pathogenicity of the complex toward G. mellonella. This combination also gave the best yields of IJs when produced in this insect and in vitro production on artificial diet.
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Affiliation(s)
- E Bonifassi
- Laboratoire de Biologie des Invertébrés, INRA, 123 Boulevard F. Meilland, Antibes Cedex, F-06606, France
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Ehlers RU, Niemann I. Molecular identification of Photorhabdus luminescens strains by amplification of specific fragments of the 16S ribosomal DNA. Syst Appl Microbiol 1998; 21:509-19. [PMID: 9924819 DOI: 10.1016/s0723-2020(98)80063-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sequence variation within the variable region of the 16S rRNA at position 440 to 480 allowed the synthesis of specific PCR primers for the identification of groups within the species Photorhabdus luminescens, symbionts of entomopathogenic nematodes of the genus Heterorhabditis. For the second PCR primer the highly conserved region at 755 to 795 was used. The P. luminescens type strain specific primer could not recognize any other P. luminescens strain. The primer TEMPERATUS based on the sequence of strain DSM12190 (isolated from North West European H. megidis strain HSH2) identified all P. luminescens associated with H. megidis from North West Europe and two isolates from closely the related nematode strains from Ireland. The primer TROPICUS based on strain DSM12191 (isolated from the nematode type strain H. indica strain LN2) identified P. luminescens of tropical origin isolated from H. indica. Symbionts of H. bacteriophora could not yet be separated into well described groups with the primers used. A comparison of sequence data resulted in the identification of additional groups. The non-symbiotic P. luminescens isolates are distinct in the variable region. The group HELIOTHIDIS contains 15 P. luminescens associated with H. bacteriophora from North East America. The MARELATUS group contains symbionts of the nematode H. marelatus from the West Coast of the US. The data together with the specific symbiotic association of P. luminescens strains with different nematode species support the division of the taxon P. luminescens into different species.
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Affiliation(s)
- R U Ehlers
- Department for Biotechnology and Biological Control, Christian-Albrechts-Universität Kiel, Raisdorf, Germany.
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Fischer-Le Saux M, Mauléon H, Constant P, Brunel B, Boemare N. PCR-ribotyping of Xenorhabdus and Photorhabdus isolates from the Caribbean region in relation to the taxonomy and geographic distribution of their nematode hosts. Appl Environ Microbiol 1998; 64:4246-54. [PMID: 9797272 PMCID: PMC106634 DOI: 10.1128/aem.64.11.4246-4254.1998] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genetic diversity of symbiotic Xenorhabdus and Photorhabdus bacteria associated with entomopathogenic nematodes was examined by a restriction fragment length polymorphism analysis of PCR-amplified 16S rRNA genes (rDNAs). A total of 117 strains were studied, most of which were isolated from the Caribbean basin after an exhaustive soil sampling. The collection consisted of 77 isolates recovered from entomopathogenic nematodes in 14 Caribbean islands and of 40 reference strains belonging to Xenorhabdus and Photorhabdus spp. collected at various localities worldwide. Thirty distinctive 16S rDNA genotypes were identified, and cluster analysis was used to distinguish the genus Xenorhabdus from the genus Photorhabdus. The genus Xenorhabdus appears more diverse than the genus Photorhabdus, and for both genera the bacterial genotype diversity is in congruence with the host-nematode taxonomy. The occurrence of symbiotic bacterial genotypes was related to the ecological distribution of host nematodes.
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Affiliation(s)
- M Fischer-Le Saux
- Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Laboratoire de Pathologie Comparée, Université Montpellier II, F-34095 Montpellier Cedex 5, France
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Forst S, Dowds B, Boemare N, Stackebrandt E. Xenorhabdus and Photorhabdus spp.: bugs that kill bugs. Annu Rev Microbiol 1997; 51:47-72. [PMID: 9343343 DOI: 10.1146/annurev.micro.51.1.47] [Citation(s) in RCA: 367] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Xenorhabdus and Photorhabdus spp. are gram negative gamma proteobacteria that form entomopathogenic symbioses with soil nematodes. They undergo a complex life cycle that involves a symbiotic stage, in which the bacteria are carried in the gut of the nematodes, and a pathogenic stage, in which susceptible insect prey are killed by the combined action of the nematode and the bacteria. Both bacteria produce antibiotics, intracellular protein crystals, and numerous other products. These traits change in phase variants, which arise when the bacteria are maintained under stationary phase conditions in the laboratory. Molecular biological studies suggest that Xenorhabdus and Photorhabdus spp. may serve as valuable model systems for studying signal transduction and transcriptional and posttranscriptional regulation of gene expression. Such studies also indicate that these bacterial groups, which had been previously considered to be very similar, may actually be quite different at the molecular level.
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Affiliation(s)
- S Forst
- Department of Biological Sciences, University of Wisconsin, Milwaukee 53201, USA.
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Brunel B, Givaudan A, Lanois A, Akhurst RJ, Boemare N. Fast and accurate identification of Xenorhabdus and Photorhabdus species by restriction analysis of PCR-amplified 16S rRNA genes. Appl Environ Microbiol 1997; 63:574-80. [PMID: 9023937 PMCID: PMC168349 DOI: 10.1128/aem.63.2.574-580.1997] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Thirteen bacterial strains of Xenorhabdus and 14 strains of Photorhabdus originating from a wide range of geographical and nematode host sources were typed by analyzing 16S rRNA gene (rDNA) restriction patterns obtained after digestion of PCR-amplified 16S rDNAs. Eight tetrameric restriction endonucleases were examined. A total of 17 genotypes were identified, forming two heterogeneous main clusters after analysis by the unweighted pair-group method using arithmetic averages: group I included all Xenorhabdus species and strains, symbionts of Steinernema, whereas group II encompassed the Photorhabdus strains, symbionts of Heterorhabditis. To identify the four valid species of Xenorhabdus and unclassified strains and all the genotypes of Photorhabdus luminescens, three restriction enzymes are required: CfoI, AluI, and HaeIII. Our results, in substantial agreement with DNA-DNA pairing and 16S rDNA sequence data, indicate that amplified 16S rDNA restriction analysis is a simple and accurate tool for identifying entomopathogenic nematode bacterial symbionts.
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Affiliation(s)
- B Brunel
- Laboratoire de Recherche sur les Symbiotes des Racines, Ecole Nationale Supérieure Agronomique de Montpellier, Institut National de la Recherche Agronomique, France
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