Succession of the microbial communities and metabolic functions in composting or deep burial processing of dead...

1. This study examined the effects of composting and deep burial techniques on degradation efficiency of dead chickens. Different raw materials (crushed branches or rape straws) and disinfectants (quicklime or bleaching powder) were applied in composting and deep burial process, respectively. The whole process lasted for 90 d in both summer and winter.2. High throughput sequencing displayed that Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria and Deinococcus-Thermus were the most dominant bacterial phyla during the experiment. The relative abundance of Firmicutes dwindled gradually with prolonged composting duration, while Proteobacteria, Bacteroidetes and Deinococcus-Thermous increased gradually over time.3. The bacterial functions identified from the KEGG pathway showed that amino acid and carbohydrate metabolism were the major microbial metabolic pathways that determined final degradation efficiency. At the end of the trial, the decomposition status of chicken carcases and faecal coliforms were measured.4. The results demonstrated that the optimum decomposition effect was obtained in composting compared with other treatment groups. Low ambient temperature reduced degradation efficiency, due to restricted microbial activity. In addition, faecal coliforms were not completely removed by the deep burial process of dead chickens in winter.5. These findings provide a theoretical basis for the feasibility of composting chicken carcases instead of deep burial.