Solid-State Fermentation of <i>Trichoderma</i> spp.: A New Way to Valorize the Agricultural Digestate and Produce Value-Added Bioproducts

Abstract

In this study, the agricultural digestate from anaerobic biogas production mixed with food wastes was used as a substrate to grow <i>Trichoderma reesei</i> RUT-C30 and <i>Trichoderma atroviride</i> Ta13 in solid-state fermentation (SSF) and produce high-value bioproducts, such as bioactive molecules to be used as ingredients for biostimulants. The <i>Trichoderma</i> spp. reached their maximum growth after 6 and 3 SSF days, respectively. Both <i>Trichoderma</i> species were able to produce cellulase, esterase, and citric and malic acids, while <i>T. atroviride</i> also produced gibberellins and oxylipins as shown by ultraperformance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) profiling. Experimental evaluation of germination parameters highlighted a significant promotion of tomato seed germination and root elongation induced by <i>T. atroviride</i> crude extracts from SSF. This study suggests an innovative sustainable use of the whole digestate mixed with agro-food waste as a valuable substrate in fungal biorefineries. Here, it has been applied to produce plant growth-promoting fungi and bioactive molecules for sustainable agriculture.