Genomic and taxonomic study of new genus candidate Pikeienuiella rasia strain RR4-56 isolated from a seawater recirculating aquaculture system

Abstract

A novel bacterium, designated strain RR4-56T, was isolated from a biofilter of a seawater recirculating aquaculture system. The 16S rRNA gene sequence analysis demonstrated that the isolate was closely related to Halovulum dunhuangense YYQ-30T (92.6%), Albimonas donghaensis DS2T (91.3%), Pontivivens insulae GYSW-23T (91.3%), and Monaibacterium marinum C7T (90.9%), that all belong to the family Rhodobacteraceae. The strain was aerobic, Gram-negative, rod-shaped, oxidase-positive, and catalase-negative. The optimum temperature, pH, and salinity for growth were 25–30 ℃, pH 8.5, and 2–3% NaCl (w/v), respectively. And the growth occurred at 15–35 ℃, pH 5.0–9.5, and 0–7% NaCl (w/v). It contained ubiquinone-10 (Q-10) as respiratory quinone and the major fatty acids were 11-methyl C18:1 ω7c (31.9%), C18:1 ω6c (30.4%), and C19:0 cyclo ω8c (16.1%). The polar lipids present in the strain were phosphatidylglycerol, unidentified phospholipid, and unidentified aminolipid. The strain has one 4,373,045 bp circular chromosome with G+C contents of 65.9 mol% including 4,169 genes, 4,118 CDSs, 3 rRNAs, and 45 tRNAs. The genome annotation predicted some gene clusters related to the degradation of several types of organic matter, which means the strain possibly has a role of the purification in the aquaculture system. Gene clusters involved in the degradation of benzoates, such as protocatechuate and catechol, were identified, and distinct from the other reference strains, phthalate-degradation-related genes were also predicted. Based on the polyphasic characteristics, RR4-56T represents a new species in a novel genus of the family Rhodobacteraceae, for which the name Pikeienuiella rasia gen. nov., sp. nov. is proposed. The type strain is RR4-56T (= KCTC 52648T = DSM 107918T).