Dynamics of microbial succession and functionality in the ecosystem of spontaneous solid-state Chinese liquor fermentation

Traditional spontaneous solid-state food fermentations are processes in complex ecosystems containing multiple and undefined microbiota, metabolites and raw materials (mainly cereals). It has a long history of safe use to meet human’s demand. However, to guarantee the yield, safety and quality of the products, these traditional uncontrolled processes are facing the challenge of standardization and sustainability. The very prerequisite to control such a complex ecosystem is to understand it. In the ecosystem of a spontaneous food fermentation, various biotic and abiotic factors are critical to microbial community function and thus metabolic profiles. Meanwhile, microbial community (with multi-species) will evolve in the dynamic fermentation stages compared with pure culture using isolated strains. For example, researches have observed abundant microbial dynamic coexistence patterns that contribute to food stability and quality during Chinese liquor (baijiu), vinegar, kefir, cheese or wine fermentation. Nevertheless, rare studies have achieved the rational control of complex bioprocess as most fermentation regulation studies have been largely limited to correlations and ex situ adapted cultures of core species in the past ten years. Deeper insights of the dynamic fermentation bioprocess are in need to obtain a large number of products (efficient bioprocessing) while ensuring the quality (sustainable food fermentation). Therefore, taking Chinese liquor fermentation as an example, we aim to systematically reveal the dynamic microbial succession and metabolic functional mechanism to better control stability of fermentation flavour and yield.