LAUSR

BACKGROUND The feasibility of fortification techniques to improve the quality of medium-temperature Daqu (MTD) by inoculation functional isolates has been demonstrated. However, it is unclear what is the effect of inoculation on the controllability during the MTD fermentation process. Here, inoculated a single strain of Bacillus licheniformis, and the microbiota composed of Bacillus velezensis and Bacillus subtilis were to investigate the synergistic effect of biotic and abiotic factors on the succession and assembly of the MTD microbiota during the process. RESULTS The biotic factors promoted the proliferation of microorganisms that arrived early at the MTD. Subsequently, this alteration might inhibit microorganisms that colonized later in the MTD microecosystem, thereby assembling a different but more stable microbial community. Moreover, the biotic factors making bacterial community assembly were dominated by variable selection earlier, while the fungal community assembly was dominated mainly by extreme abiotic factors rather than biotic factors. Interestingly, fermentation temperature and moisture were significantly associated with the succession and assembly of the fortified MTD community. Meanwhile, the effect of the environmental variables on endogenous variables was also significant. Thus, changes in endogenous variables could be mitigated by adjusting environmental variables to regulate the process of MTD fermentation. CONCLUSION Biotic factors cause rapid changes of the microbiota during the MTD fermentation process, which could be controlled indirectly by regulating environmental variables. Meanwhile, a more stable MTD ecological network might be beneficial to enhancing the stability of MTD quality. This article is protected by copyright. All rights reserved.