Abstract:
The sustainable utilization of black soldier fly (BSF) for recycling organic waste into
nutrient-rich biomass, such as high-quality protein additive, is gaining momentum, and
its microbiota is thought to play important roles in these processes. Several studies have
characterized the BSF gut microbiota in different substrates and locations; nonetheless,
in-depth knowledge on community stability, consistency of member associations,
pathogenic associations, and microbe–microbe and host–microbe interactions remains
largely elusive. In this study, we characterized the bacterial and fungal communities
of BSF larval gut across four untreated substrates (brewers’ spent grain, kitchen food
waste, poultry manure, and rabbit manure) using 16S and ITS2 amplicon sequencing.
Results demonstrated that substrate impacted larval weight gain from 30 to 100%
gain differences among diets and induced an important microbial shift in the gut of
BSF larvae: fungal communities were highly substrate dependent with Pichia being the
only prevalent genus across 96% of the samples; bacterial communities also varied
across diets; nonetheless, we observed six conserved bacterial members in 99.9%
of our samples, namely, Dysgonomonas, Morganella, Enterococcus, Pseudomonas,
Actinomyces, and Providencia. Among these, Enterococcus was highly correlated with
other genera including Morganella and Providencia. Additionally, we showed that diets
such as rabbit manure induced a dysbiosis with higher loads of the pathogenic bacteria
Campylobacter. Together, this study provides the first comprehensive analysis of
bacterial and fungal communities of BSF gut across untreated substrates and highlights
conserved members, potential pathogens, and their interactions. This information will
contribute to the establishment of safety measures for future processing of BSF larval
meals and the creation of legislation to regulate their use in animal feeds.
