Pit mud (PM) plays a key role in controlling the quality of Chinese Luzhou-flavor liquor in anaerobic fermentation. Here

microbial community composition and diversity in PM samples using pyrosequencing technique were investigated. A total of 494293 valid sequences were obtained. The reads fell into 796 operational taxonomic units (OTUs) affiliated to 21 phyla. The predominant groups were Firmicutes (66.8% of total reads)

Bacteroidetes (16.0%)

Euryarchaeota (9.0%)

Spirochaetes (2.2%)

Actinobacteria (1.8%) and Chloroflexi (1.0%). Microbial diversity increased with cellar age until 25 years old

but kept relatively constant from 25 to 50 years. A large difference between microbial communities was observed in the pit muds with different cellar ages. Lactobacillus predominanted in 1-year pit mud (62.3%)

but its abundance decreased remarkably in 10-year and older pit muds. In contrast

the abundances of Petrimonas

Clostridium IV and methanogens increased dramatically. In addition

Archaea in PM were mainly composed of hydrogenotrophic methanogens such as Methanobrevibacter

Methanoculleus

Methanobacterium

while the H2/acetate-utilizing Methanosarcina was more abundant in PM with cellar age of 25—50 years (3.1%—4.5%). This research supports the practical experience that old fermentation pits produce high quality Luzhou-flavor liquor.