Bioconversion of agro-industrial food and wastes by insects and microalgae

As the global population grows by over 9 billion in 2050, food commodity production will rise, leading to substantial amounts of agricultural waste. These residues can be used as feed for insects representing an alternative protein source for food and feed. Additionally, insect-rearing residues (frass, exuviae, etc.) can be used for other industrial applications (e.g., production of biofertilizers and chitosan). Thus, identifying optimal and low-cost substrates is essential to improve the insect's growth and nutritional composition, and to make insect rearing sustainable. Using microalgae is another promising approach to valorize agro-industrial food by-products and wastes (FBPW) of various origins. According to several studies, microalgae can effectively remove phosphorus and nitrogen while accumulating valuable biomass. Biomass from microalgae can also be exploited for several purposes, such as source of pigments, starch, and bioactive compounds.

1) FBPW will be tested as rearing substrates for Tenebrio molitor (ENEA, UNIMI) and Hermetia illucens (UNIMI). Insects’ growth, bioconversion ability and nutritional value will be monitored to find the optimal diet for each insect species. This will generate exuviae that could be exploited for extracting chitosan (UNIMI), and frass that could be tested as biofertilizers (ENEA). 
2) FBPW and wastewaters from food industries (e.g., dairies) will be used for culturing microalgae (e.g., Synechocystis sp. and Chlorella sp.). After having established pre-treatment protocols, the process will be optimized using eventually also metabolically engineered strains. The resulting microbial biomass, rich in carotenoids, will undergo extraction (IBBA-CNR).  

1. Identification of at least one optimal FBW-based diet for each insect species.

2. Optimization of insect-rearing conditions for the valorization of by-products/waste.

3. Evaluation of insect residues for chitosan production for active packaging, and insect-rearing frass efficacy as a biofertilizer.

4. Optimized protocols for balanced effluent media for the growth of algal strain growth and definitions of best growth conditions (inoculum density, temperature, light intensity, pH, etc.).

5. Set up a transformation protocol for green algae as a platform for high-value carotenoids production.