Flavobacterium phycosphaerae sp. nov. isolated from the phycosphere of Microcystis aeruginosa

Abstract

A novel aerobic bacterial strain, designated MK012(T), was isolated from the phycosphere of Microcystis aeruginosa. MK012(T) appears to be Gram-stain-negative, non-motile and rod-shaped and has yellow pigments. Phylogenetic analysis using 16S rRNA revealed that this bacterium was most closely related to Flavobacterium buctense T7(T) (=JCM 30750(T); 97.5 %), Flavobacterium dankookense ARSA-19(T) (=KCTC 23179(T); 97.5 %) and Flavobacterium macrobrachii an-8(T) (=DSM 22219(T); 97.3 %). The genome size and genomic DNA G+C content of MK012(T) were estimated at 3.3 Mbp and 37.6 mol%, respectively. The average nucleotide identity (ANI), average amino acid identity (AAI) and in silico DNA-DNA hybridization (dDDH) values of MK012(T) and the members of the genus Flavobacterium were found to be 71.8?78.3 %, 65.1-79.6% and 19.1-21.5 %, respectively. MK012(T) exhibited oxidase but no catalase activity. The cells grew at 14-36 degrees C (optimum, 25 degrees C), pH 5-10 (optimum, pH 7) and 0-0.4 % (w/v) NaCl (optimum, 0 % NaCl) in R2A medium. MK012(T) did not produce flexirubin-type pigments. The predominant cellular fatty acids of MK012(T) were determined to be iso-C-15:0, iso-C-15:0 3-OH, iso-C-17:0 3-OH, and summed feature 9 (10-methyl C-16:0 and/or iso-C-17:1 omega 9c); MK-6 was identified as its only respiratory quinone. Its major polar lipids were determined to be phosphatidylethanolamine, two unidentified aminolipids, and two unidentified polar lipids. The genotypic and phenotypic characteristics indicate that MK012(T) (=KACC 21509(T)=JCM 33879(T)) represents a novel species of the genus Flavobacterium; therefore, the name Flavobacterium phycosphaerae sp. nov. is proposed.