Proteiniclasticum sediminis sp. nov., an obligate anaerobic bacterium isolated from anaerobic sludge

An obligate anaerobic bacterial BAD-10 ^T was isolated from anaerobic acetochlor-degrading sludge. The strain was Gram-stain negative, curved rod-shaped, non-motile and non-spore-forming. Growth was observed in PYT medium at pH 6.0-9.0 (optimum, pH 7.5), at 25-47 °C (37 °C) and with 0-1.0% NaCl (w/v, 0%). Strain BAD-10 ^T could degrade acetochlor. The major fermentation products from peptone-yeast (PY) medium were acetate and butyrate. The predominant cellular fatty acids were iso-C_15:0 FAME, anteiso-C_15:0 FAME and C_16:0 FAME. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the strain BAD-10 ^T showed closest affiliation to Proteiniclasticum ruminis D3RC-2 ^T, with a sequence similarity of 97.6%. Genome sequencing revealed a genome size of 2,983,986 bp, a G + C content of 51.4 mol% and protein-coding genes of 3,102. The average nucleotide identity and in silico DNA-DNA hybridization values between strain BAD-10 ^T and Proteiniclasticum ruminis D3RC-2 ^T were 71.0% and 20.4%, respectively, which were below the standard thresholds for species differentiation. On the basis of phenotypic, physiological and phylogenetic evidence, strain BAD-10 ^T represents a novel species in the genus Proteiniclasticum, for which the name Proteiniclasticum sediminis sp. nov. is proposed. Strain BAD-10 ^T (= CCTCC AB 2021091 ^T = KCTC 25288 ^T) is the type strain of the proposed novel species.