Photorhabdus viridis sp. nov. Isolated from Heterorhabditis zealandica Entomopathogenic Nematodes.

Abstract

A novel bacterial species, Photorhabdus viridis sp. nov., represented by strain Green^T, isolated from Heterorhabditis zealandica MJ2C entomopathogenic nematodes, is described. Phylogenetic reconstructions using 16S rRNA gene sequences show that strain Green^T is closely related to P. thracensis DSM 15199 ^T. The 16rRNA gene sequences of these two strains are 98.8% identical. Phylogenetic reconstructions using whole-genome sequences show that strain Green^T is closely related to P. tasmaniensis DSM 22387 ^T, P. thracensis DSM 15199 ^T, and P. temperata DSM 14550 ^T. Digital DNA-DNA hybridization (dDDH) values between strain Green^T and its three more close relative species, P. tasmaniensis DSM 22387 ^T, P. thracensis DSM 15199 ^T, and P. temperata DSM 14550 ^T, are 49%, 59%, and 59%, respectively. In addition, average nucleotide identity (ANI) values between Green^T and P. tasmaniensis DSM 22387 ^T, P. thracensis DSM 15199 ^T, and P. temperata DSM 14550 ^T are 92.4%, 94.4%, and 94.6%, respectively. The novel species also differs in their biochemical capacities from the biochemical capacities of their more closely related taxa. The following biochemical tests may be particularly useful in this context: Arginine dihydrolase, gelatinase, and glucose and mannitol oxidation. Given the clear phylogenetic separation, the sequence divergence values, and the phenotypic differences, we conclude that strain Green^T represents a novel bacterial species, for which we propose the name Photorhabdus viridis sp. nov. with Green^T (= CCM 9407 ^T = CCOS 2117 ^T = MJ2C^T) as the type strain. Our study contributes to a better understanding of the taxonomy and biodiversity of an important bacterial group with great biotechnological and agricultural potential.