Flavobacterium ammonificans sp. nov. and Flavobacterium ammoniigenes sp. nov., ammonifying bacteria isolated from surface river water

Three aerobic. Gram-stain-negative, non-motile, rod-shaped bacteria, designated as strains SHINM13(T), GENT5(T) and GENT11 were isolated from surface river water (Saitama Prefecture, Japan). SHINM13(T) and GENT11 were positive for catalase. whereas GENT5(T) was negative. Phylogenetic analyses based on the 16S rRNA gene (1341 bp) or 40 marker gene (34,513 bp) sequences revealed that the strains formed distinct phylogenetic lineages within the genus Flavobacterium. The three strains shared 99.3-99.6% 165 rRNA gene sequence similarity among each other. The average nucleotide identity by orthology (OrthoANI) and digital DNA-DNA hybridization (dDDH) values between strains SHINM13(T) and GENT11 were 96.56 and 82.1%, respectively, and those between SHINM13(T) and GENT5(T) were 83.46% and 52.9 %, respectively. The major cellular fatty acids were C-15:1 omega 6c, iso-C-15:0, iso-C(15:1)G, anteiso-C-15:0 and iso-C-15:0 3-OH. The major polar lipid was phosphatidylethanolamine. SHINM13(T) and GENT5(T) contained menaquinone-6 (MK-6) as the predominant respiratory quinone, and their DNA G+C contents were 34.4 and 35.1 mol%, respectively. Genome sequencing of the three isolates revealed a genome size of 2.26-2.40 Mbp. Furthermore, all three isolates converted dissolved organic nitrogen to ammonium during cell growth. On the basis of the results of phenotypic and phylogenetic analyses, strains SHINM13(T) and GENT11 and GENT5(T) represent two distinct novel species in the genus Flavobacterium, for which the names Flavobacterium ammonificans sp. nov. (type strain SHINM13(T) =JCM 34684(T) =NCIMB 15379(T)) and Flavobacterium ammoniigenes sp. nov. (type strain GENT5(T) =JCM 32249(T)=NCIMB 15380(T)) are proposed.

Automated summary

Three new species of anaerobic, gram-negative, non-motile, rod-shaped bacteria were isolated from surface river water in Japan. Phylogenetic analysis revealed that these strains belong to the genus Flavobacterium. They also showed the ability to convert dissolved organic nitrogen into ammonium during cell growth.