Protein films from black soldier fly (Hermetia illucens, Diptera: Stratiomyidae) prepupae: effect of protein solubility and mild crosslinking

Electroconductive Bionanocomposites from Black Soldier Fly Proteins for Green Flexible Electronics

Printed and flexible electronics hold the potential to revolutionize the world of electronic devices. A primary focus today is their circularity, which can be achieved by using biobased materials. In this study, electrically conductive bionanocomposite materials suitable for flexible electronics were fabricated using proteins from the black soldier fly (BSF, Hermetia illucens). The valorization of BSF biomacromolecules is currently being pursued in the framework of emerging circular economy models for the bioconversion of the Organic Fraction of Municipal Solid Waste (OFMSW), where BSF has been demonstrated to act as an extremely efficient bioconverter to provide lipids, chitin, and proteins. Here, the BSF protein extracts were characterized by proteomic techniques, revealing a pool of myofibrillar proteins able to interact through intermolecular β-sheet interactions. Flexible and electroconductive bionanocomposite materials were next formulated by combining BSF proteins with a conductive carbon black (CCB), either in its pristine form or functionalized with 2-(2,5-dimethyl-1H-pyrrol-1-yl)-1,3-propanediol (serinol pyrrole, SP), using water as the only solvent and incorporating glycerol and carboxymethylcellulose (CMC) as additional green ingredients. A sustainable, low-pressure cold plasma (LPCP) technology was ultimately proposed to achieve high film surface hydrophobicity. Characterized by effective biodegradability, strain-sensing properties, high electrical conductivity (up to 0.9 × 10-2 S/cm at a filler content of 8% v/v (15% w/w)), and high surface hydrophobicity, the bionanocomposites presented here may be well suited for disposable flexible electronics, as in wearable devices, electrostatic discharge fabrics, or packaging, hence offering new routes toward OFMSW valorization and the development of green flexible electronics.

Structural characterization, HepG2 cell cytoprotective ability, and antioxidant mechanism of novel antioxidant peptides identified from black soldier fly larvae (Hermetia illucens L.)

This study isolated a novel antioxidant peptide from black soldier fly larvae (BSFL) using enzymatic hydrolysis. Firstly, the BSFL enzymatic hydrolysate was fractionated through ultrafiltration, with the <3 kDa fraction exhibiting the strongest DPPH and ABTS radical scavenging activity. Subsequently, this fraction was further fractionated through gel filtration chromatography and RP-HPLC. Totally, 153 peptides were identified through LC-MS/MS analysis, from which a novel peptide EDEGTYKCVLS (Pep6) was screened according to activity prediction and verification. Pep6 exhibited high radical scavenging capacity and cytoprotective effect on HepG2 cells against H2O2 damage, meanwhile significantly increasing the intracellular antioxidant enzymes activity. Molecular docking analysis indicated that Pep6 competitively bound to Keap1, thereby inhibiting the formation of Keap1-Nrf2 complex, ultimately protecting cells from oxidative stress damage. In this study, a novel antioxidant peptide Pep6 was identified from BSFL, and its antioxidant mechanism was elucidated, providing a theoretical basis for its use as a natural antioxidant.

Valorization of organic waste through black soldier fly: On the way of a real circular bioeconomy process

The transition from a linear to a circular production system involves transforming waste into valuable resources. Insect-mediated bioconversion, particularly using black soldier fly (BSF) larvae, can offer a promising opportunity to convert the organic fraction of municipal solid waste (OFMSW) into protein-rich biomass. However, current regulatory restrictions do not allow the use of this substrate to obtain insect proteins for animal feed, prompting the exploration of other applications, such as the production of bioplastics. Here, we explored at laboratory scale an innovative and integrated circular supply chain which aims to valorize the OFMSW through BSF larvae for the production of biobased materials with high technological value. BSF larvae reared on this organic waste showed excellent growth performance and bioconversion rate of the substrate. The use of well-suited extraction methods allowed the isolation of high-purity lipids, proteins, and chitin fractions, which are building blocks to produce biobased materials. In particular, the protein fraction was used to develop biodegradable plastic films which showed potential for replacing traditional petroleum-based materials, with the possibility to be fully recycled back to amino acids. Socioeconomic analysis highlighted values generated along the entire supply chain, and life cycle assessment pointed out that lipid extraction was the most challenging step: implementation of more sustainable methods is thus needed to reduce the overall environmental impact of the proposed chain. In conclusion, this study represents a proof of concept gathering evidence to support the feasibility of an alternative supply chain that can promote circular economy while valorising organic waste.

Microbial Enzyme Biotechnology to Reach Plastic Waste Circularity: Current Status, Problems and Perspectives

The accumulation of synthetic plastic waste in the environment has become a global concern. Microbial enzymes (purified or as whole-cell biocatalysts) represent emerging biotechnological tools for waste circularity; they can depolymerize materials into reusable building blocks, but their contribution must be considered within the context of present waste management practices. This review reports on the prospective of biotechnological tools for plastic bio-recycling within the framework of plastic waste management in Europe. Available biotechnology tools can support polyethylene terephthalate (PET) recycling. However, PET represents only ≈7% of unrecycled plastic waste. Polyurethanes, the principal unrecycled waste fraction, together with other thermosets and more recalcitrant thermoplastics (e.g., polyolefins) are the next plausible target for enzyme-based depolymerization, even if this process is currently effective only on ideal polyester-based polymers. To extend the contribution of biotechnology to plastic circularity, optimization of collection and sorting systems should be considered to feed chemoenzymatic technologies for the treatment of more recalcitrant and mixed polymers. In addition, new bio-based technologies with a lower environmental impact in comparison with the present approaches should be developed to depolymerize (available or new) plastic materials, that should be designed for the required durability and for being susceptible to the action of enzymes.

The Variety of Applications of Hermetia illucens in Industrial and Agricultural Areas-Review

Hermetia illucens (Diptera: Stratiomyidae, Linnaeus, 1978), commonly known as the black soldier fly (BSF), is a saprophytic insect, which in recent years has attracted significant attention from both the scientific community and industry. The unrestrained appetite of the larvae, the ability to forage on various organic waste, and the rapid growth and low environmental impact of its breeding has made it one of the insect species bred on an industrial scale, in the hope of producing fodder or other ingredients for various animals. The variety of research related to this insect has shown that feed production is not the only benefit of its use. H. illucens has many features and properties that could be of interest from the point of view of many other industries. Biomass utilization, chitin and chitosan source, biogas, and biodiesel production, entomoremediation, the antimicrobial properties of its peptides, and the fertilizer potential of its wastes, are just some of its potential uses. This review brings together the work of four years of study into H. illucens. It summarizes the current state of knowledge and introduces the characteristics of this insect that may be helpful in managing its breeding, as well as its use in agro-industrial fields. Knowledge gaps and under-studied areas were also highlighted, which could help identify future research directions.

Morphofunctional characterization of hemocytes in black soldier fly larvae

In insects, the cell-mediated immune response involves an active role of hemocytes in phagocytosis, nodulation, and encapsulation. Although these processes have been well documented in multiple species belonging to different insect orders, information concerning the immune response, particularly the hemocyte types and their specific function in the black soldier fly Hermetia illucens, is still limited. This is a serious gap in knowledge given the high economic relevance of H. illucens larvae in waste management strategies and considering that the saprophagous feeding habits of this dipteran species have likely shaped its immune system to efficiently respond to infections. The present study represents the first detailed characterization of black soldier fly hemocytes and provides new insights into the cell-mediated immune response of this insect. In particular, in addition to prohemocytes, we identified five hemocyte types that mount the immune response in the larva, and analyzed their behavior, role, and morphofunctional changes in response to bacterial infection and injection of chromatographic beads. Our results demonstrate that the circulating phagocytes in black soldier fly larvae are plasmatocytes. These cells also take part in nodulation and encapsulation with granulocytes and lamellocyte-like cells, developing a starting core for nodule/capsule formation to remove/encapsulate large bacterial aggregates/pathogens from the hemolymph, respectively. These processes are supported by the release of melanin precursors from crystal cells and likely by mobilizing nutrient reserves in newly circulating adipohemocytes, which could thus trophically support other hemocytes during the immune response. Finally, the regulation of the cell-mediated immune response by eicosanoids was investigated.