Obtainment of lignocellulose degradation microbial community: the effect of acid-base combination after restrictive enrichment.

Microbial communities for bioconversion of lignocellulose have received widespread attention. Many cellulose-degrading microbial communities have been enriched from different sources. Combining two microbial communities with acidic and basic properties (acid-base combination) is a technique used alongside restricted enrichment culturing. Understanding how changes to microbial communities result in community's structure and function is important for mechanistic reconstruction of microbiomes. In this study, we analyzed changes in microbial community structure to elucidate determination of the mechanisms of acid-base combination. We found that after restricted enrichment, the bacteria that were primarily retaining included not only those that decompose and utilize lignocellulose, such as Clostridium and Pseudomonas, but also synergistic microbiota such as Alkalobacillaceae. When the proportion of these two types of bacteria was unbalanced, the degradative ability of the microbial community was low, or pH changes of it did not compound regular changes, which may lead to the failure of restricted enrichment. Microbial communities were re-constituted by acid-base combination, whereby the degrading and synergistic strains were adjusted to a more appropriate proportion. The acid-base combination fixed the instability of microbial communities caused by the randomness of restrictive screening enrichment; it provided an effective method for obtaining high-quality lignocellulose-degrading microbial community.