Examining the potential of plastic-fed black soldier fly larvae (Hermetia illucens) as "bioincubators" of plastic-degrading bacteria.

AIMS: Larvae of the black soldier fly (BSFL), Hermetia illucens, are recognized for their remarkable feeding flexibility and ability to convert a variety of organic waste streams into useful end products. Their ability to feed on both harmful and recalcitrant waste streams is thought to be due in part to plasticity in their gut microbiota, which shifts rapidly to select for taxa better suited to the incoming diet. Here, we aimed to exploit this feeding plasticity by using BSFL as "bioincubators," to grow and isolate plastic-degrading bacteria. METHODS AND RESULTS: We fed larvae wheat bran containing a mix of microplastic (polyethylene terephthalate, polylactic acid, and polyhydroxybutyrate) and determined the community composition of plastic-degrading microorganisms using a combination of culturing techniques and next-generation sequencing. On average, more than a third of the gut microbiome was made up of genera that have previously demonstrated plastic degradation capabilities. To confirm this assessment, we isolated seven bacterial strains from plastic-fed BSFL that were positively identified as polyhydroxybutyrate-degraders in vitro. CONCLUSIONS: Our results provide proof of concept that plastic-fed H. illucens could be used as bioincubators to grow plastic-degrading bacteria. We believe our methodology provides a simple model for verifying in silico results with in vitro tests and should be used to enhance the future isolation and characterization of novel plastic-degrading taxa.