Investigation of the microbial community in a microbiological additive used in a manure composting process

The objectives of this study were to investigate the fate of microorganisms by using cultivation methods as well as DNA analyses in a commercial microbiological additive (MA) in the course of the composting. Almost all the predominant species in the microbial succession during composting process determined by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) were in disagreement with those determined by the clone library method. None of the microbial species in the composting stages corresponded to the microorganisms identified in the MA either by the cultivation method or DNA analysis. The results in regard to predominant microorganisms of the MA detected from the liquid medium by the PCR-DGGE did not correspond with those detected from the MA itself and composting processes. Although no evidence was found that predominant species in the MA itself dominate in the composting process, predominant species diversity in the MA itself was markedly changed after culturing at different thermophilic temperatures. These results suggested that cultivable microorganisms in the MA did not become predominant in the composting process: however, some microorganisms that are detected from the MA itself by the DNA analysis may act effectively in the composting process.