Changes in Bacterial Communities during a Pilot-Scale Composting Process of Dairy Manure

Abstract

The microbial communities involved in the composting of manure remain poorly understood. This study conducted aerobic composting of dairy manure and sawdust. Four 16S rRNA gene clone libraries were constructed from samples at Days 6, 14, 21, and 42, and a total of 375 clones were sequenced. The bacterial community structure and composition varied significantly during the composting process. Larger differences at the genus level were observed in each sample. Early in the thermophilic stage (Day 6), three main genera, Pseudomonas, Sphingobacterium, and Bacillus, were identified. Most clones affiliated with genera Cellvibrio, Devosia, Rheinheimera, and Luteimonas were detected at the thermophilic stage (Day 14). Dominant bacteria at the cooling stage (Day 21) were more diverse at the genus level, and included Flavobacterium, Myroides, Cellvibrio, Sphingobacterium, Rhodothermus, Bacillus, and Clostridium. Cellvibrio. spp increased to the highest abundance (12.4%) at the manured stage (Day 42). These results could provide a better understanding of bacterial communities during manure composting.