Characterization of the Microbial Community in a Caproic Acid-producing Bacterial Consortium (CAPBC) and Optimization of a Fermentative Medium by Taguchi Design

The caproic acid-producing bacterial consortium (CAPBC) J(30), isolated from Chinese Luzhou-flavored liquor distillery's pit mud, produces caproic acid as a metabolite. Constructed a 16S rDNA gene clone library and analyzed amplified ribosomal DNA restriction analysis, Clostridium genus was found predominating in CAPBC J(30) and C. kluyveri was the chief contributor to its caproic acid-producing ability Then based on the Daqu extraction medium, effects of different carbon sources, nitrogen sources and growth factors on the caproic acid-producing ability were investigated, among which six key factors were chosen and optimized by Taguchi design. The estimated optimal medium was the Daqu extraction medium added 10 g.l(-1)lsodium acetate, ethanol 15 ml.l(-1), liquor tailing 15 mg.l(-1), urea 3 g.l(-1), yellow mud extraction 1 ml.l(-1), and (NH4)(2)SO4 0.5 g.l(-1). After cultivated in this optimized medium for 15 days at 37 degrees C, the caproic acid yield was up to 5024.11 mg.l(-1). This optimal medium will help to produce high caproic acid of CAPBC J(30) to circumvent bottlenecks encountered in the high effective and adaptable ingredients in the field of Chinses Luzhou-flavored liquor manufacture.