Disclosing the production of fungal chitinases and proteases using insect by-products as substrates in solid-state fermentation.

Background

The world population is projected to reach nearly 9.7 billion by 2050, significantly increasing the demand for novel and sustainable protein sources. Edible insects, such as Tenebrio molitor, emerge as promising alternatives due to their high nutritional value, but adult insects and frass are direct and abundant by-products of this industry. This study aimed to valorize insect by-products through solid-state fermentation (SSF) to produce chitinases and proteases with high industrial value.

Results

Various fungi were tested in SSF, with Phanerochaete chrysosporium CECT 2777 and Aspergillus uvarum MUM 08.01 standing out as the most efficient protease producers, while Aspergillus niger CECT 2088 showed higher chitinolytic activity. Maximum chitinase (53.3 U g-1) and protease (366 U g-1) production was achieved on the 11th and 9th day of SSF of frass and adult insects, respectively, allowing the optimization of fermentation time. Increasing the solid load in SSF up to 50 g dry weight (DW) of frass did not decrease chitinase production (47.8 U g-1) compared to using 10 g DW, while protease activity decreased 70% and 44% when the quantity of adult insects increased up to 50 g DW and 100 g DW, respectively.

Conclusion

This work is pioneering in demonstrating the great potential of reusing Tenebrio molitor by-products to obtain value-added chitinases and proteases through SSF, contributing to reducing waste accumulation of insect origin and promoting the development of a circular economy. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.