Molecular analyses of the functional microbial community in composting by PCR-DGGE targeting the genes of the β-glucosidase.

The study investigated the β-glucosidase-producing microbial communities and the enzymatic dynamics of CMCase and β-glucosidase during the process of cattle manure-rice straw composting. In order to analyze the succession of functional community by PCR-denaturing gradient gel electrophoresis (DGGEs), three sets of PCR primers were designed to amplify the family 1 and 3 β-glucosidase genes from both bacteria and fungi. The results showed in general that the stable functional community composition as well as for the high level enzymatic activities of both cellulase and β-glucosidase occurred during the last phase (days 14-31) of composting. In the process of composting, that functional groups were determined by the stable bands (GH1-F, GH1-H, GH1-G, GH3E-D and GH3E-E) may significantly contribute to the increase of β-glucosidase activities in the later phase. Especially, the bands from the family 1 β-glucosidase genes were appeared before that from the family 3 β-glucosidase genes from fungi, then the former was substituted for the latter gradually in the cooling phase. We found significant correlations between the β-glucosidase activity and the communities of the functional bacteria and fungi. The results indicated that different β-glucosidase-producing microbe release different amounts or activities of β-glucosidase, and that the composition of microbial communities may play a major role in determining overall β-glucosidase activity during the composting process.