Anaerococcoides asporogena gen. nov., sp. nov., a Strictly Anaerobic Bacterium, Isolated from the Dehydrated Sludge of a Steel Factory’s Wastewater Treatment Plant

A microbial community study using a culture-dependent method was conducted on dehydrated sludge collected from a steel factory’s wastewater treatment plant. One isolate, designated QWL-01T, was a strictly anaerobic, Gram-stain-negative, non-motile, non-spore-forming bacterium with coccoid cells measuring 0.6–0.9 μm in diameter. The growth of strain QWL-01T was observed at 4–40 °C (optimum at 28–35 °C), pH 5.5–8.0 (optimum at pH 7.1), and a range of 0–3% NaCl (optimum at 0.5%). An analysis of the Biolog AN plate revealed positive carbon source utilization only for palatinose, α-ketovaleric acid, and pyruvic acid. The predominant fatty acids were iso-C13:0 (17.0%), C16:0 dimethyl acetal (12.0%), and anteiso-C13:0 (9.2%). A 16S rRNA gene sequence analysis through BLASTN demonstrated that the nearest phylogenetic neighbors of the novel strain were Youngiibacter multivorans DSM 6139T (93.82%) and Proteiniclasticum ruminis JCM 14817T (93.75%). The genome size of strain QWL-01T was 3.69 Mbp, with a G+C content of 50.8 mol%. Comparing strain QWL-01T with closely related species of genera Proteiniclasticum and Youngiibacter, the digital DNA-DNA hybridization (dDDH), average nucleotide identity (ANI), and average amino acid identity (AAI) values ranged from 26.60% to 36.80%, 65.89% to 68.30%, and 49.27% to 51.58%, respectively. Based on phenotypic, physiological, phylogenetic, and genomic relatedness evidence, strain QWL-01T represents a novel genus in the family Clostridiaceae, for which the name Anaerococcoides asporogena gen. nov. sp. nov. is proposed. Strain QWL-01T (=BCRC 81396T = CICC 25258T = NBRC 117088T) is the type strain of the proposed novel species.