Deinococcus piscis sp. nov., a radiation-resistant bacterium isolated from a marine fish

Abstract

A radiation-resistant, Gram-stain-positive, non-motile, non-sporulating, aerobic, coccoid bacterium, strain 3ax(T), was isolated from a marine fish (black pomfret, Parastromateus niger), with radiation as a selective pressure. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 3ax(T) exhibited highest similarity (97.9 %) with Deinococcus proteolyticus DSM 20540(T). The DeltaT(m) for DNA-DNA hybridization of D. proteolyticus DSM 20540(T) and strain 3ax(T) was 15.3 degrees C, indicating that the novel strain was distinct from D. proteolyticus DSM 20540(T). The predominant respiratory quinone was MK-8. Strain 3ax(T) could grow at 20-42 degrees C; the optimum temperature for growth was 35 degrees C. The strain grew well at pH 6-9, with optimum growth at pH 7. The cell wall contained ornithine. The major fatty acids were 16 : 0, 16 : 1omega7c, 16 : 1omega9c and 18 : 1omega9c. Three phosphoglycolipids and one aminophospholipid were the major polar lipids. Based on the genotypic, phenotypic and chemotaxonomic characteristics, strain 3ax(T) was significantly different from D. proteolyticus DSM 20540(T) and, therefore, it was identified as representing a novel species of the genus Deinococcus, for which the name Deinococcus piscis sp. nov. is proposed. The type strain is 3ax(T) (=MTCC9123(T) =DSM 19767(T)).