Rapidly mitigating antibiotic resistant risks in chicken manure by Hermetia illucens bioconversion with intestinal microflora

Abstract

Summary Antibiotic resistance genes (ARGs) in animal manure are an environmental concern due to naturally occurring bacteria being exposed to these wastes and developing multidrug resistance. The bioconversion of manure with fly larvae is a promising alternative for recycling these wastes while attenuating ARGs. We investigated the impact of black soldier fly (BSF, Hermetia illucens) larval bioconversion of chicken manure on the persistence of associated ARGs. Compared with traditional composting or sterile larval treatments (by 48.4% or 88.7%), non‐sterile BSF larval treatments effectively reduced ARGs and integrin genes by 95.0% during 12 days, due to rapid decreases in concentrations of the genes and associated bacteria as they passed through the larval gut and were affected by intestinal microbes. After larval treatments, bacterial community composition differed significantly, with the percentage of Firmicutes possibly carrying ARGs reduced by 65.5% or more. On average, human pathogenic bacteria populations declined by 70.7%–92.9%, effectively mitigating risks of these bacteria carrying ARGs. Environmental pH, nitrogen content and antibiotic concentrations were closely related to both bacterial community composition and targeted gene attenuation in larval systems. Selective pressures of larval gut environments with intestinal microbes, larval bacteriostasis and reformulation of manure due to larval digestion contributed to ARG attenuation.

Effects of different levels of Hermetia illucens larvae meal on performance, egg quality, yolk fatty acid composition and oxidative status of laying hens

“…The increased feed intake observed in the laying hens of present study can be attributed to the improvement of the diet palatability related to HILM (Bovera et al 2015;Cullere et al 2016). It is possible to assume that the improvement of production performance is related to the improvement of metabolism, immunity and intestinal health (Cutrignelli et al 2018;Cai et al 2018;Sypniewski et al 2020). However, Schiavone et al (2018) showed that 50% or 100% replacement of soybean oil with HILM in broiler chickens diets has no adverse effects on the daily feed intake or feed conversion ratio.…”

Reference gene selection for quantitative gene expression analysis in black soldier fly (Hermetia illucens)

“…Second, due to exposure to heavy metals and antibiotics in the environment (especially in pig manure), there have been many studies on heavy metals and antibiotics in H . illucens [45–47].…”

Identification of Bacteria in Two Food Waste Black Soldier Fly Larvae Rearing Residues

“…Wynants et al (2018) studied BSFL rearing with a variety of mostly grain-based substrates in several laboratory and industry-scale settings, Jiang et al (2019) with food waste in an industry-scale setting, and Bruno et al (2019) with a standard substrate for fly rearing, vegetables and fish waste in a laboratory setting ( Table 3). Considering that substrate digestion by BSFL (Cai et al, 2018;Bruno et al, 2019) and other fly larvae (e.g., Lucilia sericata, Diptera: Calliphoridae) (Mumcuoglu et al, 2001;Lerch et al, 2003) decreases bacterial richness along the digestive tract (Gold et al, 2018;Vogel et al, 2018), different feeding rates, intervals, and larval densities among studies could be especially relevant ( Table 3). One could expect that the substrate and residue bacterial community is altered to a greater extent by BSFL when less feed is provided per larvae (i.e., lower feeding rate and/or higher larval density).…”

“…Jiang et al (2019) were the first to determine bacterial community dynamics throughout one rearing cycle and found that BSFL rearing affects and alters the substrate bacterial community over time to increase the capacity to decompose the substrate. Lalander et al (2013) and Erickson et al (2004) also reported a reduction in certain bacteria during BSFL rearing, and Cai et al (2018) and Liu et al (2020) reported a reduction in antibiotic resistance genes in bacteria. These results contradict the findings of Bruno et al (2019), who did not identify a significant influence of BSFL on substrate microbiota during rearing.…”