D3202: Evaluation of the effects of bokashi fermentation of feedstocks on black soldier fly (Hermetia illucens) gut microbiomes

Large-scale rearing of the black soldier fly Hermetia illucens (Diptera: Stratiomyidae) (BSF) for sustainable bioconversion is a rapidly growing industry. BSF larvae (BSFL) promote a circular economy by upcycling agricultural waste into valuable biomass for feedstock and fertilizer amendments. BSFL exhibit lower pathogen susceptibility compared to other edible insects and can grow in suboptimal rearing conditions. However, contaminated substrates pose a potential risk of zoonotic disease transmission in the downstream use of BSF products in feed and agriculture. Bokashi substrate fermentation is an anaerobic composting strategy that increases larvae performance and reduces greenhouse gas emissions. As a substrate pretreatment, bokashi fermentation may mediate pathogen inoculation risks and optimize the decontamination of organic waste. This study aims to explore the effect of bokashi fermentation on the microbial diversity of the BSFL gut microbiome. Understanding substrate pretreatment and fermentation on BSFL is important for optimizing rearing operations and reducing potential health risks. In this study, we fed BSFL fermented and unfermented brewery’s spent grains in addition to a control Gainesville diet. We also removed the intestinal tract of mature fifth instar larvae and extracted DNA in preparation for sequencing. After successfully preparing samples for 16S ribosomal RNA Illumina sequencing, I aim to characterize and determine the abundance of microbes within the BSFL digestive tract. I expect the digestive tracts of larvae reared in unfermented spent grains to exhibit an increased diversity and abundance of coliforms compared to larvae fed bokashi fermented spent grains.