A Molecular Survey of Bacterial Species in the Guts of Black Soldier Fly Larvae (Hermetia illucens) Reared on Two Urban Organic Waste Streams in Kenya

Abstract

Globally, the expansion of livestock and fisheries production is severely constrained due to the increasing costs and ecological footprint of feed constituents. The utilization of black soldier fly (BSF) as an alternative protein ingredient to fishmeal and soybean in animal feed has been widely documented. The black soldier fly larvae (BSFL) used are known to voraciously feed and grow in contaminated organic wastes. Thus, several concerns about their safety for inclusion into animal feed remain largely unaddressed. This study evaluated both culture-dependent sequence-based and 16S rDNA amplification analysis to isolate and identify bacterial species associated with BSFL fed on chicken manure (CM) and kitchen waste (KW). The bacteria species from the CM and KW were also isolated and investigated. Results from the culture-dependent isolation strategies revealed that Providencia sp. was the most dominant bacterial species detected from the guts of BSFL reared on CM and KW. Morganella sp. and Brevibacterium sp. were detected in CM, while Staphylococcus sp. and Bordetella sp. were specific to KW. However, metagenomic studies showed that Providencia and Bordetella were the dominant genera observed in BSFL gut and processed waste substrates. Pseudomonas and Comamonas were recorded in the raw waste substrates. The diversity of bacterial genera recorded from the fresh rearing substrates was significantly higher compared to the diversity observed in the gut of the BSFL and BSF frass (leftovers of the rearing substrates). These findings demonstrate that the presence and abundance of microbiota in BSFL and their associated waste vary considerably. However, the presence of clinically pathogenic strains of bacteria in the gut of BSFL fed both substrates highlight the biosafety risk of potential vertical transmission that might occur, if appropriate pre-and-postharvest measures are not enforced.

Bacterial biota composition in gut regions of black soldier fly larvae reared on industrial residual streams: revealing community dynamics along its intestinal tract

“…To elaborate on these findings, this work also looked at additional substrates to test that assumption and included, for the first time, the analysis of the microbial community in the hindgut. In fact, to the best of our knowledge, the microbial composition of BSF larval gut was analyzed either on the whole organ (Klammsteiner et al, 2020;Shumo et al, 2021;Zhang et al, 2021;IJdema et al, 2022) or by subdividing the midgut in its three main regions (Bruno et al, 2019b). The introduction of the hindgut as separate sample provides new, interesting insights.…”

Isolation and identification of bacteria with capability of starch, cellulose and protein decomposition from Frass of Black Soldier Fly (Hermetia Illucens) Larvae

“…and Bordetella sp. were detected in KW [29]. When screened and isolated bacteria from the gut of Black Soldier larvae treated rice straw feed, Supriyatna, and Ukit (2016) [30] found that six out of nine cellulose degrading bacteria belonged to Bacillus, where Bacillus sp.…”

Effects of Disinfectants on Larval Growth and Gut Microbial Communities of Black Soldier Fly Larvae

“…According to a previous study, Morganella morganii and Providencia spp. together have the ability to produce urease, which results in the generation of significant amounts of biogenic amines, which could neutralize the gut’s acidic digestive fluids, preventing some bacterial species from being hydrolyzed [ 37 ]. Thus, the decline of Morganella and Providencia in GT1–2 and PT1–2 might have an impact on larval digestion and the gut microbial composition.…”