Aquabacterium pictum sp. nov., the first aerobic bacteriochlorophyll a -containing fresh water bacterium in the genus Aquabacterium of the class Betaproteobacteria

A strictly aerobic, bacteriochlorophyll -containing betaproteobacterium designated strain W35 , was isolated from a biofilm sampled at Tama River in Japan. The non-motile and rod-shaped cells formed pink-beige pigmented colonies on agar plates containing organic compounds, and showed an absorption maximum at 871 nm in the near-infrared region, typical for the presence of bacteriochlorophyll . The new bacterial strain is Gram-negative, and oxidase- and catalase-positive. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain W35 was closely related to species in the genus . The closest phylogenetic relatives of strain W35 were B8 (97.9 % sequence similarity), B4 (97.2 %) and ABP-4 (97.0 %). The major cellular fatty acids were C ω7 (50.4 %), C (22.7 %), summed feature 8 (C ω7 /C ω6 ; 9.7 %), C ω6 (5.5 %), C (5.3 %) and C 3OH (2.7 %). The respiratory quinone was ubiquinone-8. Predominant polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The G+C content of the genomic DNA was 70.4 mol% (genome data) and 71.4 mol% (HPLC). The genome size of strain W35 is 6.1 Mbp and average nucleotide identity analysis indicated genome similarities of strain W35 and related type strains to be 78-79 %. The results of polyphasic comparisons showed that strain W35 was clearly distinguishable from other members of the genus . Therefore, we propose a new species in the genus , namely, sp. nov. The type strain is W35 (=DSM 106757 =NBRC 111963 ). The description of the genus is also emended.