Characterization of gas profiles and bacterial community dynamics during the decomposition of pig carcasses in simulated soil burial and composting systems

Pilot-scale test systems simulating soil burial and composting of pig carcasses were constructed in field, and monitored the changes in temperature and gas for 340days. The envelope material samples were collected using special sampling devices without disturbance, and bacterial community dynamics were analyzed by high-throughput pyrosequencing. Soil temperature increased to 25°C on the 180th day and then gradually decreased to 10°C. The compost temperature reached 40°C on the 85th day and then remained over 44°C even after the 334th day. The intensities of odor gases from the compost bin were higher than those from the soil pit. Based on the odor gas profiles and the morphological properties of carcasses excavated, it was estimated that the active and advanced decay stages were reached earlier by composting than by soil burial. The dominant bacterial communities in the soil were aerobic and/or facultatively anaerobic gram negative bacteria such as Pseudomonas, Gelidibacter, Mucilaginibacter, and Brevundimonas. However, the dominant bacteria in the composting system were anaerobic, thermophilic, endospore-forming, and/or halophilic gram positive bacteria such as Pelotomaculum, Lentibacillus, Clostridium, and Caldicoprobacter. Different dominant bacteria played important roles in the decomposition of pig carcasses in the soil and compost. This study provides useful comparative date for the degradation of pig carcasses in the soil burial and composting systems.