Strong-Flavor Baijiu Pit Mud Microbiome in the Context of Modern Industry: From a Black Box Under Empiricism to the Gradual Revelation of Microbial Ecosystems

Abstract

Chinese strong-flavor Baijiu (CSFB), one of the most popular categories in the alcoholic beverage market, is supposed to comply with the current industry development trend and achieve mechanization, modernization, and unification of production. Solid-state fermentation in the mud cellar is the fundamental characteristic of CSFB. Pit mud, which provides the necessary conditions for producing the precursors of crucial flavor substances, plays a decisive role in CSFB's characteristics and quality. How to intervene and regulate the microbiome of pit mud, either using top-down or bottom-up approaches, to ultimately obtain an ecosystem that consistently provides the characteristic flavor substances in unified, standard, and mechanized production has become an urgent problem to be solved. This review summarizes the current knowledge of the pit mud microbiome in Baijiu fermentation, focusing on evolution and assembly patterns, functional roles, and ecological succession over batch-to-batch fermentation for decades or even centuries. Key challenges are identified, including controlling microbial interactions and enabling standardized, large-scale production of microbiome adaptations. This review also explores the application of advanced techniques such as omics tools and synthetic community design to improve microbiome regulation. We hold the view that the understanding of pit mud microbial ecosystems combined with technological advances provides an opportunity for intelligent microbiome management. By utilizing these tools, the production of CSFB can move in the direction of more consistent flavor and better quality control, with the potential for significant improvements in microbial engineering and industrial practices.