Simultaneous reductions in antibiotic, antibiotic resistance genes and nitrogen loss during bioaugmentation tylosin fermentation dregs co-composting

Abstract

Considering the main problems presented in the typical solid wastes antibiotic fermentation dregs (AFDs) composting that the residual antibiotics could result in the propagation of antibiotic resistance genes (ARGs), and the reduced value of agronomic production caused by the ammonia gas (NH3) emissions. This study established a bio-augmented tylosin fermentation dregs (TFDs) aerobic co-composting system to investigate the effects of a novel isolated high-efficiency strain Klebsiella sp. TN-1 inoculation on tylosin degradation, reduction in ammonia emissions, and ARG abundances during this process.Results showed that the application of strain Klebsiella sp. TN-1 extended the thermophilic stage and promoted compost maturity. Moreover, bio-enhanced co-composting with strain Klebsiella sp. TN-1 led to a totally degradation of tylosin, and removed most of ARGs, metal resistance genes (MRGs) and mobile genetic elements (MGEs), and also effectively reduce ammonia emission by 49.76 %.via increasing ammoxidation rates. Principal co-ordinates analysis further suggested that the strain Klebsiella sp. TN-1 had little influence on the bacterial community composition, while the changes of other physical and chemical properties during this process were the main reasons for the evolution of bacterial community and propagation of ARGs in the TFDs co-composting.This study suggests the potential of the bio-enhanced strain Klebsiella sp. TN-1 for antibiotic biodegradation and its application for nitrogen conservation in the AFDs co-composting process, which could decrease the risk of ARGs spreading and make compost products more secure.