Dynamics of physicochemical properties, microbial composition, and antibiotic and antibiotic resistance genes during chicken manure composting with strain T4

Co-composting of chicken manure and edible mushroom residue inoculated with oxytetracycline-degrading strain T4 was conducted to reduce the risk of residual oxytetracycline and tetracycline resistance genes (TRGs) to the ecological environment.

Three treatments (CK: without bacteria agent T4 inoculated; AM: 1% bacteria agent T4 inoculated in mesophilic phase; AC: 1% bacteria agent T4 inoculated in cooling phase) were set to investigate dynamics of physicochemical properties, microbial composition, and antibiotic and antibiotic resistance genes.

The bacteria agent T4 inoculated in the mesophilic phase was conductive to the reservation of nutrients and maturity of chicken manure and improved oxytetracycline degradation (t_1/2 was 2.77 days, and the total degradation rate was 80.78%). Bacterial community dynamic analysis showed that strain T4 reduced microbial richness and diversity in composting. In addition, the bacteria agent T4 could reduce the relative abundance of encoding efflux pump (EFP) TRGs significantly, and inoculated in the mesophilic phase was better than the cooling phase while having little effect on ribosomal protection protein (RPP) TRGs and enzymatic inactivation (EI) TRG.

Inoculation of strain T4 in the initial stage of composting could be a promising technology to solve the problem of oxytetracycline residue and its resistance genes in chicken manure. It was also found that the abundance of TRGs was affected by bacterial composition and dynamic, which was affected by the physicochemical properties of composting and fates of oxytetracycline, and vice versa.