Pseudomonas fildesensis sp. nov., a psychrotolerant bacterium isolated from Antarctic soil of King George Island, South Shetland Islands

The strain KG01(T) was isolated from a soil sample from King George Island, Antarctica. Cells of KG01(T) are rod-shaped and motile by means of multiple polar flagella. The absence of arginine dihydrolase activity could be a key feature to readily distinguish KG01(T) from its closest phylogenetic relative species. The main fatty acids of the strain include summed feature 3 (C-16:1 omega 7c and/or C-15:0 iso 2-OH), C-16:0 and C-18:1 omega 7c. Phylogenetic analysis based on the 16S rRNA gene sequence and on a multilocus sequence analysis (MLSA) using housekeeping genes (16S rRNA, rpoB, rpoD, gyrB) were carried out. These analyses allowed us to include the strain within the Pseudomonas fluorescens group, presenting the highest similarity of multilocus sequence with Pseudomonas veronii LMG 17761(T) (96.67%). The genome of KG01(T) was sequenced and in silico compared with genomes of the most closely related species of the P. fluorescens group. The average nucleotide identity (ANIb) and average amino acid identity (AAI) values of the species phylogenetically closest to KG01(T) were less than 95-96%, threshold currently accepted to define strain as belonging to a bacterial species, the highest scores being those to Pseudomonas veronii LMG 17761(T) (87.98%) and Pseudomonas marginalis ICMP 3553(T) (91.90%). Therefore, the phenotypic and genotypic analyses results, allow us to propose that KG01(T) represents a member of a novel species of the genus Pseudomonas, for which the name Pseudomonas fildesensis is proposed, and KG01(T) (=CECT 9084(T);=DSM 102036(T)) is established as the type strain.