Impact of Processed Food (Canteen and Oil Wastes) on the Development of Black Soldier Fly (Hermetia illucens) Larvae and Their Gut Microbiome Functions

Abstract

Canteens represent an essential food supply hub for educational institutions, companies, and business parks. Many people in these locations rely on a guaranteed service with consistent quality. It is an ongoing challenge to satisfy the demand for sufficient serving numbers, portion sizes, and menu variations to cover food intolerances and different palates of customers. However, overestimating this demand or fluctuating quality of dishes leads to an inevitable loss of unconsumed food due to leftovers. In this study, the food waste fraction of canteen leftovers was identified as an optimal diet for black soldier fly (Hermetia illucens) larvae based on 50% higher consumption and 15% higher waste reduction indices compared with control chicken feed diet. Although the digestibility of food waste was nearly twice as high, the conversion efficiency of ingested and digested chicken feed remains unparalleled (17.9 ± 0.6 and 37.5 ± 0.9 in CFD and 7.9 ± 0.9 and 9.6 ± 1.0 in FWD, respectively). The oil separator waste fraction, however, inhibited biomass gain by at least 85% and ultimately led to a larval mortality of up to 96%. In addition to monitoring larval development, we characterized physicochemical properties of pre- and post-process food waste substrates. High-throughput amplicon sequencing identified Firmicutes, Proteobacteria, and Bacteroidota as the most abundant phyla, and Morganella, Acinetobacter, and certain Lactobacillales species were identified as indicator species. By using metagenome imputation, we additionally gained insights into the functional spectrum of gut microbial communities. We anticipate that the results will contribute to the development of decentralized waste-management sites that make use of larvae to process food waste as it has become common practice for biogas plants.

Growth efficiency, intestinal biology, and nutrient utilization and requirements of black soldier fly (Hermetia illucens) larvae compared to monogastric livestock species: a review

“…Using a metagenomics approach Dysgonomonas sp. were identified by Klammsteiner et al [ 129 ] and Jiang et al [ 80 ]. The same methodology was used to identify a cellulase (CS10) in BSFL that belongs to the glycosyl-hydrolase family 5 with one catalytic domain, broad pH spectrum and optimal activity at pH 6 and 50 °C [ 130 ].…”

16S rRNA Gene Sequencing Reveals Specific Gut Microbes Common to Medicinal Insects

“…In many insect species, Dysgonomonas are involved in complex polysaccharide degradation ( Bruno et al, 2019 ), competent to break down abundant α-galactose in indigestible plant carbohydrates ( Lee et al, 2018 ), and positively associated with genes for sulfate, carbohydrate, and nitrogen metabolism ( Jiang et al, 2019 ). Morganella contributes to the stabilization of the intestinal flora of insects ( Duarte et al, 2018 ), and clinically, it is considered as a pathogenic microorganism associated with insects for feed and food because of its potential to cause serious infections ( Raimondi et al, 2020 ; Klammsteiner et al, 2021 ). Actinomyces facilitate the degradation of lignin and chitin, are usually symbiotic in the gut of various animals, and produce various antibiotics to inhibit the growth of other microorganisms, which are also beneficial to larvae ( Wang et al, 2014 ; Hanning and Diaz-Sanchez, 2015 ; Klammsteiner et al, 2020 ; Tanga et al, 2021 ).…”

“…Some samples of P. americana (Food waste rearing) were donated by Shandong Kunpeng Agricultural Development Co., Ltd. (Jinan, China), and the samples of P. brevitarsis (Edible fungi residue rearing) were provided by CangZhou Academy of Agriculture and Forestry Sciences (Cangzhou, China). The remaining gut microbial raw sequence data were obtained from NCBI 1 , including a total of 104 samples for the medicinal insects (10 samples for M. domestica and 94 samples for P. americana ), and a total of 89 samples for non-medicinal insects (12 samples for D. melanogaster , 66 samples for H. illucens , and 11 samples for T. molitor ) ( Tinker and Ottesen, 2016 ; Leftwich et al, 2017 ; Zhao et al, 2017a ; Li H. et al, 2019 ; Cifuentes et al, 2020 ; Klammsteiner et al, 2020 , 2021 ; Peng et al, 2020 ; Shelomi et al, 2020 ; Urbanek et al, 2020 ) ( Supplementary Table 1 ).…”

Directional Changes in the Intestinal Bacterial Community in Black Soldier Fly (Hermetia illucens) Larvae

“…Several researchers have found that environmental and feeding sources have a significant influence on the overall composition of the insect microbial community [ 14 ], such as Hermetia illucens intestinal microbiota [ 28 , 52 , 53 ] and Drosophila melanogaster gut microbiota [ 54 ]. Thus, before sequencing data analysis, it was supposed that all of the group samples would have more target bacteria in them because the larvae were fed sterile food waste with different target bacteria.…”