Caproiciproducens puteiluti sp. nov. and Caproiciproducens lactatisolvens sp. nov., isolated from the pit mud of strong-flavour Baijiu distilleries

Two Gram-stain-positive, anaerobic, non-motile, non-spore-forming, rod-shaped bacteria, designated strains R1^T and R2^T, were isolated from pit mud. Both strains were oxidase-negative and catalase-negative. Strain R1^T grew at pH 5.0-9.0 (optimum 6.0-7.0), 25-45 °C (optimum 30-40°C) and in 0-2.5 % NaCl. Strain R2^T grew at pH 5.0-10.0 (optimum 6.0-8.0), 25-45 °C (optimum 30-40°C) and in 0-2.5 % NaCl. The major cellular fatty acids of both strains were C_{14 : 0}, C_{16 : 0}, summed feature 1 (C_{15 : 1} iso H and/or C_{13 : 0} 3OH) and summed feature 3 (C_{16 : 1} <i> ω</i>7<i>c</i> and/or C_{16 : 1} <i> ω</i>6<i>c</i>). Polar lipids included diphosphatidylglycerol, phosphatidylglycerol, phospholipids, unidentified polar lipids and glycolipids. The cell wall peptidoglycan contained <i>meso</i>-diaminopimelic acid. DNA G+C contents were 51.35 mol% (R1^T) and 52.38 mol% (R2^T). Based on 16S rRNA gene sequences, strains R1^T and R2^T exhibited sequence similarities of 98.53% and 98.19% to '<i>Caproiciproducens faecalis</i>' AGMB10547^T and 96.68% and 96.48% to <i>Caproiciproducens galactitolivorans</i> BS-1^T, respectively. The orthologous average nucleotide identity values/digital DNA-DNA hybridization values with closest relatives (≤84.62%/≤28.90%) fell below prokaryotic species thresholds, while genome-based relatedness between novel strains (94.21%/58.00%) supported separate species status. Based on phenotypic, phylogenetic and chemotaxonomic characteristics, strains R1^T and R2^T represent two novel species of <i>Caproiciproducens</i>, for which the names <i>Caproiciproducens puteiluti</i> sp. nov. and <i>Caproiciproducens lactatisolvens</i> sp. nov. are proposed, respectively. The type strains of <i>C. puteiluti</i> and <i>C. lactatisolvens</i> are R1^T (=GDMCC 1.5535^T=KCTC 25972^T) and R2^T (=GDMCC 1.5536^T=KCTC 25973^T), respectively.