Abstract
In the study presented herein, an aerobic, Gram-stain-positive, spore-forming bacterium, designated as WLY-B-L8(T), was isolated from a qu-starter (baobaoqu) cultivation facility used for the production of Wuliangye baijiu in Yibin city (Sichuan province, China). The strain comprised short, rod-shape cells of 1.2-1.9 μm in width and 1.7-4.8 μm in length, arranged singly or in pairs. The isolate was able to grow at temperatures of 20-42 °C (optimum growth at 40 °C), pH 5.0-10.0 (optimum growth at pH 8.0), and in the presence of 0-2% (w/v) NaCl (optimum growth with 1% NaCl). Ribose, xylose, arabinose, mannose, glucose, and galactose constituted the major cell-wall sugars. Moreover, meso-diaminopimelic acid (meso-DAP) constituted the diagnostic amino acid. The main polar lipids of WLY-B-L8(T) included diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), unidentified aminolipids (UAL 1-2), an unidentified aminophospholipid (UAPL), an unidentified aminoglycolipid (UAGL), and an unidentified lipid (UL). MK-7 was the predominant menaquinone and iso-C(15:0) (23.00%) was the major fatty acid. Comparisons of the 16S rRNA gene sequence indicated that WLY-B-L8(T) was most closely related to Bacillus rhizoplanae JJ-63 DSM 12442(T) (98.71%), Bacillus pseudomycoides DSM 12442(T) (98.21%), and Bacillus cytotoxicus NVH 391-98(T) (98.14%). The average nucleotide identity (ANI) values of strain WLY-B-L8(T) and the three type strains mentioned above were 88.24%, 80.57%, and 78.70%. The average amino identity (AAI) values between them were 89.84%, 79.51%, and 80.41%. In addition, the digital DNA-DNA hybridization (dDDH) values between them were 36.70%, 26.10%, and 23.90%. The genomic DNA G+C content was 35.97%. Based on the evidence presented herein, WLY-B-L8(T) (CICC 25210(T) = JCM 36284(T)) exhibits promise as the type strain of a novel species, designated as Bacillus multifaciens sp. nov., that can produce protease (119.38 ± 7.44 U/mL) and volatile flavor components when cultured on raw wheat, such as 2-pipendinone (21.95 ± 1.56 mg/L), phenylethyl alcohol (19.08 ± 0.82 mg/L), hydrocinnamic acid (18.60 ± 0.53 mg/L), and acetoin (7.58 ± 0.11 mg/L).