Pseudomonas chlororaphis subsp. piscium subsp. nov., isolated from freshwater fish

Abstract

Gram-negative, aerobic, motile, rod-shaped bacteria were isolated from the intestines of freshwater fish on two separate occasions. Colonies of both strains, JF3835T and JF4413, produced non-diffusible green pigment following 4–5 days incubation on Luria–Bertani agar. The most abundant fatty acids were summed feature 3 (comprising C16 : 1 ω7c and/or C15 : 0 iso 2-OH), C16 : 0 and C18 : 1 ω7c. The DNA G+C content was 62.9 mol%. Sequence analysis of the 16S rRNA gene indicated 100 % sequence similarity between the two strains. In comparison with recognized species, the new strains exhibited the greatest degree of sequence similarity with members of the Pseudomonas chlororaphis subspecies: P. chlororaphis subsp. chlororaphis (99.84 %), P. chlororaphis subsp. aurantiaca (99.75 %) and P. chlororaphis subsp. aureofaciens (99.40 %). While DNA–DNA relatedness confirmed the placement of strains JF3835T and JF4413 as members of the species P. chlororaphis, multilocus sequencing indicated that the strains formed a distinct cluster within it. On the basis of genotypic and phenotypic evidence, strains JF3835T and JF4413 represent a novel subspecies of the species P. chlororaphis, for which the name Pseudomonas chlororaphis subsp. piscium subsp. nov. is proposed. The type strain is JF3835T (=NCIMB 14478T=DSM 21509T).