Fungus Reduces Tetracycline-Resistant Genes in Manure Compost by Predation of Bacteria

Antibiotic resistance has emerged as one of the most pressing global threats to public health. This study showed that the fungus Phanerochaete chrysosporium seeded to the composting reactor (CR) could remarkably reduce tetracycline-resistant genes (TRGs). It was found that the reduction efficiencies of the five main TRGs (i.e. tetW , tetO , tetM , tetPA , and tet(32) ) were increased by a factor 8 to 100 as compared to the control without addition of P. chrysosporium . This could be attributed to the observed decrease in the quantity of bacteria, while the enumeration based on green-fluorescence protein labeling further showed that P. chrysosporium became dominant in CR. On the other hand, bacteria in compost could invade the fungal cells via the cell wall defect of chlamydospore or active invasion. It appeared that the invasive bacteria locked in the fungus could not survive, resulting in bacterial death and degradation of their TRGs by the fungal nucleases. As such, it is reasonable to consider that the predation of tetracycline-resistant bacteria by fungus was mainly responsible for the enhanced removal of TRGs in compost. Thus, this study may offer new insights into microbial control of antibiotic resistant genes.