Open AccessPhotorhabdus khanii subsp. guanajuatensis subsp. nov., isolated from Heterorhabditis atacamensis, and Photorhabdus luminescens subsp. mexicana subsp. nov., isolated from Heterorhabditis mexicana entomopathogenic nematodes
Author(s) -
Ricardo A. R. Machado,
Pamela Bruno,
Carla C. M. Arce,
Nicole Liechti,
Angela Köhler,
Julio S. Bernal,
Rémy Bruggmann,
Ted C. J. Turlings
Publication year - 2019
Publication title -
international journal of systematic and evolutionary microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 173
eISSN - 1466-5034
pISSN - 1466-5026
DOI - 10.1099/ijsem.0.003154
Subject(s) - biology , photorhabdus luminescens , photorhabdus , heterorhabditis , housekeeping gene , microbiology and biotechnology , strain (injury) , 16s ribosomal rna , bacteria , gene , genetics , botany , biological pest control , gene expression , anatomy
Two Gram-negative, rod-shaped, non-spore-forming bacteria, MEX20-17 T and MEX47-22 T , were isolated from the digestive system of Heterorhabditis atacamensis and Heterorhabditis mexicana entomopathogenic nematodes, respectively. Their 16S rRNA gene sequences suggest that strains MEX20-17 T and MEX47-22 T belong to the γ-Proteobacteria and to the genus Photorhabdus. Deeper analyses using housekeeping-gene-based and whole-genome-based phylogenetic reconstruction suggest that MEX20-17 T is closely related to Photorhabdus khanii and that MEX47-22 T is closely related to Photorhabdus luminescens. Sequence similarity scores confirm these observations: MEX20-17 T and P. khanii DSM 3369 T 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 MEX47-22 T and P. luminescens ATCC 29999 T 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 MEX20-17 T and MEXT47-22 T 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 MEX20-17 T (=LMG 30372 T =CCOS 1191 T ) and Photorhabdus luminescenssubsp. mexicana subsp. nov. with the type strain MEX47-22 T (=LMG 30528 T =CCOS 1199 T ). These propositions automatically create Photorhabdus khanii subsp. khanii subsp. nov. with DSM 3369 T as the type strain (currently classified as P. khanii), and Photorhabdus luminescenssubsp. luminescenssubsp. nov. with ATCC 29999 T as the type strain (currently classified as P. luminescens).