Biodegradation of polyurethane by black soldier fly larvae and the function of gut microorganisms

The unreasonable disposal of polyurethane leads to resource waste and environmental pollution. Black soldier fly (Hermetia illucens) larvae facilitate the bioconversion of various organic wastes, but the degradation of polyurethane by black soldier fly larvae and the response mechanism of black soldier fly larvae gut microorganisms remain unclear. In this study, a s tandard diet (CK), polyurethane foam, and starvation were applied to rear black soldier fly larvae. We found that 82% of black soldier fly larvae survived, and their weight increased by 19 mg per larva after 16 d of feeding with polyurethane foam and water. The consumption rate of polyurethane was 0.35 mg/day per larva, and the cellular texture of polyurethane foam was damaged. X-ray photoelectron spectrometer and Fourier transform infrared spectroscopy suggested that ester, ether and urethane bonds were cracked. Analysis of gut microorganisms indicated that Dysgonomonas, Morganella, and Klebsiella were the most abundant genera in CK, while Providencia, Scatolibacter, and Chryseobacterium were the most abundant genera in polyurethane, indicating that gut microbial community could respond to a harsh environment and offer a stable survival and adaption strategy for black soldier fly larvae. In addition, a polyurethane-degradation strain from black soldier fly larvae gut named Delftia sp. A2 was isolated, suggesting the potential of gut microorganisms to discover other functional strains. In summary, we found that black soldier fly larvae could survive and gain weight with the polyurethane as the sole substrate and polyurethane consumption influenced gut microbial community.