Microbial diversity of traditional fermentation starters for Hong Qu glutinous rice wine as determined by PCR-mediated DGGE

Hong Qu glutinous rice wine, one of the most popular traditional rice wines in China, is brewed from glutinous rice with the addition of two traditional fermentation starters – Hong Qu (hóng qū) and Yao Qu (yào qū). In this study, the microbial compositions of fungi and bacteria associated with these two fermentation starters were investigated by nested PCR-denaturing gradient gel electrophoresis (DGGE). The bacterial DGGE profile targeting the V3 region of the 16S rRNA gene indicated that the bacterial composition of starters was highly variable in species composition and dominated by Bacillus species, including Bacillus ginsengihumi, Bacillus megaterium or Bacillus aryabhattai, Bacillus subtilis, Bacillus methylotrophicus and Bacillus amyloliquefaciens. Lactic acid bacteria (LAB) including Weissella paramesenteroides, Pediococcus pentosaceus and Pediococcus acidilactici were also detected in some fermentation starters. In analysis of fungi, PCR-DGGE fingerprints revealed that Rhizopus oryzae, Rhizopus microsporus and Aspergillus sp. were the most frequent species in Yao Qu, while Monascus sp. dominated in Hong Qu. Three non-Saccharomyces yeasts (Saccharomycopsis fibuligera, Pichia guilliermondii and Pichia farinose) were also detected in some starter samples. Multivariate comparisons of DGGE fingerprints showed the complex bacterial and fungal communities were different between Hong Qu and Yao Qu. The Shannon–Weaver diversity index (H′) and Simpson dominance index (D), calculated from the DGGE profiles also showed considerable qualitative differences in the community structure between Hong Qu and Yao Qu. PCR-DGGE was found to be useful for evaluating the quality and the type of traditional wine starters. The prevalence of potential spoilage microorganism highlights the need for more attention when evaluating the microbiological safety of naturally fermented, traditional food products. Moreover, the above results are relevant for the development of starter cultures and predictability of fermentation process for traditional Hong Qu glutinous rice wine, and to aid their intermediate and large scale production. ► First comparative molecular ecological study on Hong Qu glutinous rice wine starter. ► PCR-DGGE was useful for evaluating the quality of traditional rice wine starters. ► Predominant and potential spoilage microorganisms were identified.