Analysis of Beijing Douzhir Microbiota by High-Throughput Sequencing and Isolation of Acidogenic, Starch-Flocculating Strains

Abstract

Beijing Douzhir is a traditional Chinese fermented drink produced by the natural fermentation of mung beans as the raw material. Ma tofu is an edible by-product of Douzhir processing. Douzhir microbiota, particularly bacteria involved in the natural fermentation process, has not been clearly established, resulting in limited industrial Douzhir production. Here, three uncooked Douzhir samples (D group) and three uncooked Ma tofu samples (M group) (two replicates per sample) were collected from three manufacturers in different locations in Beijing. The composition and diversity of the bacterial communities in each sample were analyzed by high-throughput sequencing. In total, 637 operational taxonomic units (OTUs) were revealed in the D group through database alignment, and 656 OTUs were found in the M group. The Chao, ACE, and Shannon indices were not significantly different in Douzhir samples from different manufacturers (p > 0.05). Representatives of six phyla were found in all 12 samples. Dominant bacteria were isolated and identified using mung bean juice as the growth medium. In both Douzhir and Ma tofu samples, dominant bacteria belonging to Firmicutes and Proteobacteria comprised > 94% of the total microbiota. The dominant bacteria included members of the Lactococcus, Acetobacter, Streptococcus, and Lactobacillus genera. Considering the dominant-microbiota information, we employed a plate-separation technique and isolated two strains of acid-producing bacteria from the Douzhir and Ma tofu samples with starch-flocculating activity: Acetobacter indonesiensis and Lactococcus lactis subsp. lactis. Such strains can serve as a foundation for the standardized industrial production of Douzhir.

Fermentation improves flavors, bioactive substances, and antioxidant capacity of Bian-Que Triple-Bean Soup by lactic acid bacteria

“…Accordingly, a strain of Lactococcus lactis subsp . lactis YM313 screened from Beijing Douzhir which had excellent fermentation flavor ( Xu et al, 2018 ) and a strain of Lacticaseibacillus casei YQ336 screened from soybean acid slurry which could rapidly produce acid ( Xu et al, 2019 ) were used as a starter culture for TBS fermentation. The volatile flavor substances changes in TBS and Bian-Que Triple-Bean Soup after fermentation (FTBS) were analyzed by SPME-GC–MS and electronic nose.…”

The Relationship between Microbial Community Succession and Flavor Formation during the Natural Fermentation of Hongqu sufu

“…Xu Qiong et al [9] used HTS to sequence the genes in the 16 SrDNAV1-V3 regions of the Hongqu sufu strain to analyze the bacterial diversity in Hongqu sufu in different regions, and the research deepened the understanding of bacterial community composition and diversity in Hongqu sufu. Many studies have applied this technique to the analysis of microbial diversity during fermentation, such as in tempeh [10], bean juice [11], miso [12], Qula [13], and so on. In terms of research on sufu flavor compounds, Ran Chunxia et al reported the following finding [14]: the extraction and analysis of volatile compounds of sufu by headspace solid-phase microextraction gas chromatography-mass spectrometry technology combined with headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) technology indicates that HS-SPME-GC-MS technology is most mature for the analysis of flavor compounds in sufu.…”