Molecular analyses of the diversity and function of the family 1 β-glucosidase-producing microbial community in compost.

Abstract

The diversity and transcription efficiency of GH1 family β-glucosidase genes were investigated in natural and inoculated composts using a DNA clone library and real-time qPCR. Compositional differences were observed in the functional communities between the two composting processes. Proteobacteria, Actinobacteria, Firmicutes, and Chloroflexi were the dominant phyla. Twenty representative β-glucosidase genes were quantitatively analyzed from the DNA and RNA pools. Principal component analysis and Pearson's correlation analysis showed that cellulose degradation is correlated with the composition and succession of functional microbial communities, and this correlation was mainly observed in Proteobacteria and Actinobacteria. Compared with inoculated compost, the functional microbial communities in natural compost with a low diversity index exhibited a weak buffering capacity for function in response to environmental changes. This may explain the consistency and dysfunction of cellulose degradation and transcriptional regulation by dominant β-glucosidase genes. Except for the β-glucosidase genes encoding constitutive enzymes, individual β-glucosidase genes responded to environmental changes more drastically than the group β-glucosidase genes. The correlation results suggested that β-glucosidase genes belonging to Micrococcales play an important role in the regulation of intracellular β-glucosidase. These results indicated that the responses of functional microorganisms were different during both composting processes and were reflected at both the individual and group levels.