Regulation of cereal protein on the microbial and metabolic diversity during the Chinese liquor fermentation

Abstract:

[Background] Cereal protein of raw material can provide nutrients such as nitrogen sources for the growth of microbial community, and then form a variety of metabolites during Chinese liquor fermentation. Cereal protein includes albumin, globulin, kafirin and gluten. However, the regulation of cereal protein on microbial diversity and metabolic diversity is still unclear. [Objective] This study aimed to reveal the key cereal protein that are significantly related to microbial diversity, and the effect of their regulation on microbial diversity and metabolic diversity. [Methods] The cereal protein was determined by Osborne's method; Identification of microbial diversity and metabolic diversity via HS-SPME-GC-MS and high-throughput sequencing during fermentation with 4 cultivars of sorghum. The key cereal protein was verified by simulated fermentation in vitro. [Results] The cereal protein of 4 sorghum was significant difference (ANOSIM:R=0.85, P=0.001); The bacterial diversity of sorghum S4 was significantly higher than others (P<0.05) at day 5 of fermentation with 4 sorghum; The metabolic diversity of sorghum S3 was significantly higher than others (P<0.05) at day 5 of fermentation with 4 sorghum. The contents of albumin and globulin were significantly correlated with the dominant bacterial diversity (R²=0.34, P<0.05; R²=0.58, P<0.05) and metabolic diversity (R²=0.58, P<0.05; R²=0.36, P<0.05) at day 5 of fermentation. Thus, they are defined as the key cereal protein; In vitro validation confirmed that the dominant bacterial diversity and metabolic diversity would increase with the increase of albumin and globulin content. When the albumin content is 3.0 g/L, the dominant bacteria diversity and metabolite diversity are 0.72 and 0.65, respectively; when the globulin content is 3.0 g/L, the dominant bacterial diversity and metabolite diversity are 0.66 and 0.81, respectively. [Conclusion] The study revealed the regulation of albumin and globulin in raw material on the diversity of bacteria and metabolites, and providing a new perspective for improving the controllability and quality of Chinese liquor fermentation.