Contributions of thermotolerant bacteria to organic matter degradation under a hyperthermophilic pretreatment process during chicken manure composting

Abstract

Composting technology comprising hyperthermophilic pretreatment (at ≥85 °C for 2 to 4 h, HTPRT) and aerobic composting was adopted to accelerate organic matter transformation and enhance nitrogen retention in chicken manure composting. The differences in physio-chemical parameters, successions, and metabolism functions of the bacterial community between HTPRT (85 °C, 4 h) and conventional composting (CK) were compared. The HTPRT composting system reached maturity 18 days in advance of CK. The HTPRT piles showed a lower maximum N loss (27.1% vs. 39.0%). The bacterial structure in the HTPRT system differed remarkably from that in CK. Ureibacillus (22.7%) and Ammoniibacillus (14.1%) were the most predominant species in the thermophilic phase of HTPRT pile, while the curing phase was dominated by Thermobifida (12.8%) and Saccharomonospora (11.8%). The authors' results suggest that HTPRT improved the physical properties of the feedstock by reducing the bulk density, which favored microbiological activity, and thus improving composting efficiency.