Sporolactobacillus fermentans sp. nov., an obligately anaerobic and lactic acid bacterium isolated from pit mud

A gram-positive, endospore-forming bacterial strain CQH2019 ^T was successfully isolated from pit mud samples of Chinese Nongxiang-flavor Baijiu. The cells were anaerobic, Gram-positive, rod-shaped, with 0.5–0.8 µm in width and 3–5 µm in length. The optimal growth conditions are 37°C, pH 5.5 and NaCl concentrations of 0.5%. This obligate chemoorganoheterotrophic strain utilized complex organic compounds, carbohydrates (L-arabinose, D-xylose, D-galactose, D-fructose, D-mannose, L-rhamnose, and D-tagatose), organic salts (potassium gluconate), glycosides (amygdalin, arbutin, salicin) and produced acetate, butyric and lactic acid as end products from RCM. The predominant cellular fatty acids (> 10%) of stain CQH2019 ^T were anteiso-C17:0 (29.95%), C16:0 (17.47%) and anteiso-C15:0 (14.42%). Phylogenetic analysis based on 16S rRNA gene sequences revealed the closest relatives were S. putidus QC81-06 ^T (95.74%), S. vineae SL153 ^T (95.74%), S. pectinivorans GD201205 ^T (95.38%) and S. shoreae BK92 ^T (95.19%). The size of the genome was 4.5 Mb and the DNA G + C content was 47.58%. The digital DNA-DNA hybridization (dDDH) values between CQH2019 ^T and these closely related strains were ranged from 19.3% to 26.8%, whereas the whole-genome average nucleotide identity (ANI) values were 69.26 − 82.78%. These polyphasic taxonomy analysis results indicate that strain CQH2019 ^T represents a novel species based on both criteria. Also based on polyphasic analysis, strain CQH2019 ^T represents a novel species within the genus Sporolactobacillus , for which the name Sporolactobacillus fermentans sp. nov. is proposed. The type strain is CQH2019 ^T (= MCCC 1A19398 ^T  = KACC 23552 ^T ).