Utilization of agricultural waste for the production of Trichoderma spores via solid-state fermentation

Abstract

Trichoderma sp. production through solid-state fermentation represents a promising strategy for agricultural bioinputs. In this study, two agricultural residues, corn cob and coffee husk, were evaluated as substrates for Trichoderma sp. spores production. Both substrates were subjected to alkaline hydrolysis (2.4 % NaOH for 30 min) and heat treatment (90 °C for 10 min). In addition, the effect of nutrient supply with KH₂PO₄, (NH₄)₂SO₄, urea, and CaCl₂ was evaluated. Precooked rice (90°C for 5 min), conventionally used for fungal production, was used as control substrate. Spore production was monitored over a 20-day incubation period. Conidial viability, dry weight yield, and axenicity of the final product were determined. The results showed a progressive increase in sporulation throughout the incubation period. The highest yield was obtained with heat-treated coffee husk supplemented with nutrients, reaching 5.04 × 10¹⁰ spores/g of substrate, with conidial viability above 98 %, a dry weight yield of 3.35 %, and no detectable microbial contamination. Similarly, heat-treated corn cob supplemented with nutrients achieved 4.83 × 10¹⁰ spores/g of substrate, with viability above 98 %, a dry weight yield of 3.07 %, and no detectable microbial contamination. The control treatment consisting of nutrient-supplemented rice produced 5.10 × 10¹⁰ spores/g of substrate, with no detectable microbial contamination and a dry weight yield of 3.8 %. These results show that the agricultural residues, particularly when subjected to heat treatment and nutrient supplementation, are suitable substrates for efficient production of Trichoderma sp., being an alternative to conventional substrates.