Abstract: Revealing the ecological roles of rare and abundant taxa in the whole bacterial community in a fermentation system can provide clues for understanding the bacterial community structure and its succession pattern during fermentation. In the present study, we investigated the roles and functions of the rare taxa (RT), conditionally rare taxa (CRT) and abundant taxa (AT) sub-communities in the whole bacterial community during the third round of stacking fermentation via high-throughput sequencing. In general, the results showed that the three sub-communities displayed distinct succession patterns. The high level of alpha diversity in the RT sub-community suggested its important role in maintaining the ecological stability of the whole bacterial community during fermentation. The species-time relationship (STR) model implied that the reduction in the number of species in the bacterial community was primarily attributable to the rapid decrease in the RT sub-community. The time-decay relationship (TDR) model combined with the results of Mantel test and β diversity contribution suggested that AT determined the strength and trend of succession of the whole bacterial community, and that CRT boosted them. RT microbes were located at the center of the co-occurrence network, thereby evidencing their roles in maintaining the ecological stability. The constrained correspondence analysis (CCA) showed that the succession patterns of the distinct sub-communities were significantly correlated with specific endogenous physicochemical factors. Moreover, the responses of CRT microbes to environmental changes were more sensitive than the other sub-communities, and structural variations in CRT could impact the whole community system.

Key words: succession pattern; ecological system; endogenous physicochemical factors; β diversity; co-occurrence network