Microbial Community Dynamics During the Composting Process of Animal Manure as Analyzed by Molecular Biological Methods

Abstract

Composting is a useful technique that transforms livestock manure into stable organic fertilizer. In composting, the biodegradation of substrates is conducted by microbial communities of bacteria, archaea, and fungi. Bacteria are assumed to play an important role in the decomposition of organic substances. However, only a few studies have tracked bacterial communities throughout the composting process. Furthermore, the role of archaea in composting remains to be fully elucidated. To uncover the dynamics of these bacterial and archaeal communities, a variety of molecular biological methods like PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) and clone library were utilized. A clone library constructed from bacterial 16S rRNA genes showed that the structure of the bacterial community changed dynamically with compost processing time. At first, phyla Firmicutes and Bacteroidetes were dominant. Phylum Firmicutes maintained abundance for 20 days, indicating that these bacteria may be active under high temperatures. In the final compost, the library consisted of sequences belonging to the phyla Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria.