Cytoprotective and Antioxidant Effects of Hydrolysates from Black Soldier Fly (Hermetia illucens).

The black soldier fly (BSF), Hermetia illucens, has been recognized as one of the most promising insect species for its ability to valorize organic waste while producing a valuable larval biomass with a great potential as a sustainable source of nutrients, including proteins and bioactive molecules. In the present study, BSF larvae were used to produce and characterize the protein hydrolysates (BPHs) that were then evaluated for their potential biological activity in vitro. The BPHs obtained from the BSF larvae proteins by enzymatic digestion were characterized by Nuclear Magnetic Resonance (NMR) and polyacrylamide gel electrophoresis and assessed for their antioxidant activity (BPHs in the range of 0.1 to 1.5 mg/mL) in L-929 cells. Our findings show that BPHs can exert a dose-dependent cytoprotective role against H2O2-iduced oxidative stress in cells. This antioxidant activity relies on the reduction of ROS levels in challenged cells as measured by flow cytometry and fluorescence microscopy, together with the induction and nuclear translocation of Nrf2, as evaluated by qPCR and indirect immunofluorescence analysis, respectively. Overall, our findings on the remarkable biological activity of the BPHs obtained in a large-scale process strongly suggest the application of BPHs as ingredients promoting animal health in feed formulations.

Black Soldier Fly (Hermetia illucens) Larvae and Prepupae Defatted Meals in Diets for Zebrafish (Danio rerio).

The black soldier fly (BSF) Hermetia illucens is receiving increasing attention as a sustainable fishmeal alternative protein source for aquaculture. To date, no studies have explored the effects of fishmeal replacement with BSF V instar larvae or prepupae meals due to their peculiar nutritional properties on fish performances. This study investigated the effects of 100% replacement of fishmeal (control diet) with defatted BSF meals (V instar larvae and prepupae meals, treatments) on growth performance and welfare of zebrafish (Danio rerio), from larvae to adults, in a 60-day feeding trial. Following the inclusion of BSF meals, the expression of key genes involved in growth (igf1, igf2, mstnb, myod1, myog, myf5), hydrolysis of chitin (chia.2, chia.3, chia.5), immune- (il1b, il6, tnfα), and stress- (hsp70 and nr3c1) responses, as assessed by qPCR, was modulated in all of the molecular pathways, except for the stress response. Overall, our findings showed that both BSF meals can totally replace fishmeal without adverse impacts on adult zebrafish growth parameters (final total and standard length, final body weight, weight gain, daily growth rate, specific growth rate) and welfare, with BSF prepupae meal inducing the most beneficial effects, thus suggesting their potential application to meet fish requirements in aquaculture.

Waste Valorization via Hermetia Illucens to Produce Protein-Rich Biomass for Feed: Insight into the Critical Nutrient Taurine.

Insects have been recognized as sustainable alternative sources of nutrients for food and feed. The Black Soldier Fly (BSF), Hermetia illucens, is a particularly promising species for its great potential in the waste valorization to produce, during the bioconversion process, high-value fat and proteins that currently represent a valuable source for fish feed. The present study aims to evaluate the efficiency to use substrate proteins in two different BSF developmental stages as sustainable biotechnological tools for vegetable waste management. We provide insights into the nutritional values of both V instar larvae and prepupae in terms of valuable amino acids with special focus on taurine, a crucial nutrient for fish. Moreover, we cloned four key genes from BSF involved in the taurine biosynthesis pathway, 2-aminoethanethiol dioxygenase (Hiado), cysteine dioxygenase (Hicdo), cysteine sulfonate decarboxylase (Hicsad), and glutamate decarboxylase (Higad). The gene expression analysis in larvae and prepupae by qPCR showed development-specific profiles suggesting they influence the taurine content during BSF development. These findings showed peculiar phenotypes in larvae and prepupae that can be selected for different biotechnological applications as sustainable source of relevant amino acids and taurine to support the increasing demand for animal feed and aquafeed in the next decades.

Hermetia illucens (Diptera: Stratiomydae) larvae and prepupae: Biomass production, fatty acid profile and expression of key genes involved in lipid metabolism.

The Black Soldier Fly (BSF) Hermetia illucens provides a promising strategy in the waste valorisation process and a sustainable alternative source of valuable nutrients, including lipids for food and feed. In the present study, the differences in growth performances and nutritional values of BSF V instar larvae and prepupae reared on vegetable waste were analyzed and compared focusing on fat content. V instar larvae showed higher capacity to bioconvert the substrate into biomass than prepupae. The nutritional composition and the fatty acid profiles were dependent on the developmental stage. The expression levels of acetyl-CoA carboxylase (acc), fatty acid synthase (fas), lipase (lip) and acyl-CoA dehydrogenase (acd) genes involved in the lipid metabolism pathway and herein characterized for the first time, were evaluated in order to understand the molecular basis underlying the observed differences in fatty acid profiles. Our results suggest that the different fatty acid profiles of BSF V instar larvae and prepupae may be related to the modulation of the lipid metabolism-related genes expression during larval development. Our study highlights substantial differences between H. illucens V instar larvae and prepupae giving important features regarding the opportunity to modulate the preferable fatty acid profile to meet the industrial requirements.

Molecular characterization and expression analysis of heat shock protein 70 and 90 from Hermetia illucens reared in a food waste bioconversion pilot plant.

Two full-length cDNAs of heat shock protein (HSP) genes (Hihsp70 and Hihsp90) were cloned from the black soldier fly (BSF) Hermetia illucens larvae reared in a food waste bioconversion pilot plant. The Hihsp70 and Hihsp90 transcripts were 2243 and 2507bp long, contained 1923 and 2166bp open reading frames encoding proteins of 640 and 721 amino acids with a molecular mass of 69.8 and 83kDa, respectively. Comparative analysis of protein sequences revealed the presence of the conserved HSP motifs in both proteins, showing high homology to their counterparts in other insect species from six different orders. Hihsp70 and Hihsp90 transcriptional expression profiles during two key developmental stages in the bioconversion process were evaluated by quantitative real time PCR showing that both genes were modulated during larval development. HiHsp70 mRNA expression levels during the II instar larvae was higher in respect to the V instar larvae. A similar difference in mRNA expression levels, but in a less extent, was found for the Hihsp90. Moreover, a diverse transcript level between the two genes at the V larval stage was observed where Hihsp90 was up-regulated compared to Hihsp70. These results suggested the involvement of Hsp70 and Hsp90 in H. illucens development and provide further evidences on the ecological and evolutionary importance of HSPs in the insect developmental processes together with valuable information on molecular features of adaptability to peculiar rearing conditions during food waste bioconversion.