Description of Pseudomonas gorinensis sp. nov., a plant growth-promoting bacterium that modulates stomatal aperture.

Abstract

A polyphasic taxonomic approach was used to characterize a previously isolated plant growth-promoting Pseudomonas strain designated as NT2^T and a Pseudomonas strain designated as TKP (JCM 19688), both of which were found to manipulate plant stomatal immunity. Both strains shared 100% 16S rRNA gene sequence identity. Phylogenetic trees based on single and concatenated sequences of the housekeeping genes gyrB, rpoB, rpoD and 16S rRNA, as well as whole-genome sequences, clustered NT2^T and TKP together, clearly separated from the closest Pseudomonas spp., which belonged to the Pseudomonas fluorescens complex. NT2^T showed average nucleotide identities (ANIs) of 87.8% (ANIb) and 89.9% (ANIm) and a 37.4% digital DNA-DNA hybridization score with Pseudomonas grimontii DSM 17515^T, the species with the highest genome sequence similarity. On the contrary, the comparison between NT2^T and TKP showed very high ANI (ANIb=99.67, ANIm=99.93) and digital DNA-DNA hybridization scores (98.90%). NT2^T and TKP differed from closely related species in relation to arginine dihydrolase activity, aesculin and gelatin hydrolysis, N-acetyl-d-glucosamine, maltose, adipate, phenylacetate, p-hydroxy-phenylacetic acid, Tween 40, glycyl-l-proline, d-maltose, d-galactonic acid lactone, α-hydroxy butyric acid, myo-inositol, sucrose, l-histidine, d-malic acid, l-rhamnose and acetic acid assimilation, NaCl-tolerance range and pyocyanin production (fluorescence on King A medium). The major fatty acids in NT2^T and TKP were C16 : 0, C16 : 1 ω7t and C18 : 1 ω7c. The results of this polyphasic study allowed the genotypic and phenotypic differentiation of NT2^T and TKP from the closest Pseudomonas and confirmed that these strains represent a novel species, for which the name Pseudomonas gorinensis sp. nov. is proposed with NT2^T (DSM 114757^T=LMG 32751^T) as the type strain.