Fibrivirga algicola gen. nov., sp. nov., an algicidal bacterium isolated from a freshwater river

An aerobic, gram-stain-negative, pink-colored, non-motile and rod-shaped algicidal bacterium, designated as JA-25(T) was isolated from freshwater in Geumgang River, Republic of Korea. Strain JA-25(T) grew at 15-30 degrees C and pH 6-9, and did not require NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain JA-25(T) belongs to the family 'Spirosomaceae' and is most closely related to Fibrella aestuarina BUZ 2(T) (93.6%). Strain JA-25(T) showed < 90% sequence similarity to other members of the family 'Spirosomaceae'. The average nucleotide identity(ANI), in silico DNA-DNA hybridization and average amino acid identity(AAI) values based on the genomic sequences of JA-25(T) and F. aestuarina BUZ 2(T) were 74.4, 20.5, and 73.6%, respectively. Strain JA-25(T) showed an algicidal effect on the marine flagellate alga Heterocapsa triquetra, but no effect on fresh water cyanobacterium (Nostoc). In genome analysis, RIPP-like peptides were detected and predicted to resemble the indolmycin biosynthetic gene cluster, which possibly influence its algicidal effect. Furthermore, a bacteriorhodopsin gene with photoheterotrophic characteristics was detected. The genomic DNA G + C content was 52.5 mol%. The major cellular fatty acids were summed feature 3 (C16:1 omega 6c/C16:1 omega 7c), C16:1 omega 5c, C16:0 (> 10%). The major respiratory quinone was menaquinone 7 and major polar lipids were phosphatidylethanolamine, two unidentified aminolipids, two phospholipids, and five unidentified lipids. Considering the phylogenetic inference, phenotypic, and chemotaxonomic data, strain JA-25(T) should be classified as a novel species in the novel genus Fibrivirga, with the proposed name Fibrivirga algicola sp. nov. The type strain is JA-25(T) (= KCCM 43334(T) = NBRC 114259(T)).