Profiling the Clostridia with butyrate-producing potential in the mud of Chinese liquor fermentation cellar

• Published in: International journal of food microbiology 2019-05, Vol.297, p.41-50
• Main Authors: Chai, Li-Juan, Xu, Peng-Xiang, Qian, Wei, Zhang, Xiao-Juan, Ma, Jian, Lu, Zhen-Ming, Wang, Song-Tao, Shen, Cai-Hong, Shi, Jin-Song, Xu, Zheng-Hong
• Format: Article
• Language: English
• Subjects: Acetic acid; Alcoholic Beverages - microbiology; Aroma; Bacilli; Bacillus - enzymology; Bacillus - genetics; Bacteria; Butyrate kinase; Butyrates - metabolism; Butyric acid; Clostridia; Clostridial community structure; Clostridium; Clostridium - enzymology; Clostridium - genetics; Clostridium isolation; Fermentation; Fermentation pit mud; Flavor; Functional groups; Gene sequencing; Kinases; Microbiota; Microbiota - genetics; Microorganisms; Mud; Relative abundance; RNA, Ribosomal, 16S - genetics; rRNA 16S; Soil Microbiology; Solid state fermentation; Species; Strong-flavour baijiu
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2019.02.023

Butyrate and its derivates pertain to the key aroma contributors of strong-flavour baijiu, a kind of Chinese liquors, that is produced from grains by solid-state multispecies anaerobic fermentation in a mud cellar. Microbes inhabiting in the fermentation pit mud largely determines baijiu's flavour and quality. In order to shed light on the microbial functional groups driving butyrate production in pit mud, clone library analysis was firstly performed and the results demonstrated that Clostridia (relative abundance: 50%) and Bacilli (37%) were major groups possessing butyrate kinase (buk) pathway and Clostridia (98%) dominated butyryl-CoA:acetate CoA-transferase (but) pathway. According to Clostridial specific-16S rRNA gene sequencing analysis, we found the resilience character of Clostridial community in pit mud. Amongst Clostridial groups, 32.0% of the sequences were grouped into Clostridiales incertae sedis, followed by Heliobacteriaceae (18.3%) and Clostridiaceae 1 (8.4%). Moreover, Hydrogenispora, Sedimentibacter and Clostridium were the top three abundant genera. Relative abundance of Hydrogenispora was higher in the late days of fermentation, while Sedimentibacter exhibited higher proportion in the early days. Different from the previous studies using universal bacterial primer sets, Hydrogenispora was first reported as one dominant genus in pit mud. As for the reported potential butyrate producer Clostridium, nineteen species were obtained and ten of them were first isolated from the pit mud. Amongst them, buk was identified in eleven species by PCR analysis, while but was identified in the other seven, indicating the species-specific butyrate synthesis pathways of Clostridium. This study provides a perspective on targeting and isolating specific functional microbes in baijiu microbiota with the gene sequence-based medium prediction method. •Clostridia dominated both but and buk butyrate synthesis pathways in pit mud.•Abundant Hydrogenispora, Sedimentibacter and Clostridium characterized the pit-mud Clostridial consortium during brewing.•Nineteen Clostridium species with divergent butyrate formation capacity were isolated.•Species-specific butyrate synthesis features of Clostridium were revealed.•Dynamic changes of Clostridial community in pit mud during brewing were first reported.