Abstract: This study aimed to understand the microbial diversity of rice wine koji in Guizhou and to compare the bacterial and fungal community structures of rice wine kojis from different regions of this province. The composition and structure of bacterial and fungal communities in Huaxi (A), Panzhou (B) and Anshun (C) kojis were analyzed by high-throughput sequencing of the bacterial 16S rDNA V3-V4 region and of the fungal ITS1 region. Then the basic physicochemical indicators of kojis were determined and correlated with the diversity of major bacterial populations. The results showed that a total of 129 510 bacterial effective sequences and 1 030 operational taxonomic units (OTUs) were obtained, together with 60 945 fungal effective sequences and 19 OTUs. The bacterial diversity analysis showed that the Shannon index in koji B was significantly lower than those in kojis A and C, while the bacterial community structures of kojis A and C were more similar. The fungal diversity analysis showed that the Shannon index in koji C was significantly lower than those in kojis A and B, and the fungal community structures of kojis A and B were more similar to each other. At the level of phylum, Proteobacteria was the dominant bacteria and Zygomycota was the dominant fungi in koji A; Firmicutes was the dominant bacteria and Zygomycota was the dominant fungi in koji B; Proteobacteria was the dominant bacteria and Ascomycota was the dominant fungi in koji C. At the genus level, the dominant bacteria of koji A was Rhodococcus, and the dominant genus of kojis C and B was Bacillus. The dominant fungal genus of both kojis A and B was Rhizopus, while the dominant fungal genus of koji C was Saccharomyces. There was a significant regional variation in the microbial composition and diversity in rice wine koji at both the genus and phylum levels. The physicochemical indicators exhibited a correlation with the bacterial community structure.

Key words: koji, microbial diversity, high-throughput sequencing, environmental factors