Black soldier fly larvae can effectively degrade oxytetracycline bacterial residue by means of the microbial community and antibiotic resistance genes in their gut

Antibiotic bacterial residue is a unique hazardous waste, and its safe and effective disposal has always been a concern of pharmaceutical enterprises. The black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), is a saprophytic insect that can digest organic waste efficiently and in an environmentally friendly way. Here, the feed mixture was formulated as 0:1 (CK), 1:20 (TW), and 1:2 (TD) oxytetracycline bacterial residue:soya meal (mass ratio, dry weight). The degradation of OBR and oxytetracycline, the microbial community, the incidence of antibiotic resistance genes (ARGs) and the microbial function of the gut were examined. The highest oxytetracycline tolerance of the larvae ranged from 3042~4653 mg kg-1 dry weight. When the larvae were harvested, 70.83%, 59.30% and 54.54% of the substrates had been consumed for CK, TW and TD, respectively. Moreover, 65.85% and 63.28% of the oxytetracycline was degraded effectively in TW and TD, respectively. These findings demonstrate that OBR can be reduced effectively by black soldier fly larvae with intestinal microorganisms, and the larvae can be used as a bioremediation tool for the treatment of hazardous waste. Finally, the abundant ARGs and MGEs in the gut deserve further attention and should be considered in environmental health risk assessments.