Reaproveitamento do resíduo agroindustrial de arroz para cultivo microbiano

Abstract

Biological control has emerged as a promising alternative to agrochemicals for pest and disease management, driven by the growing demand for more sustainable agricultural practices. Among the microorganisms employed, the filamentous fungus Trichoderma harzianum stands out for its potential in both biological control and plant growth promotion, typically cultivated in solid-state fermentation (SSF) using rice as the main substrate. At the end of the cultivation process, this rice becomes an underutilized residue with no established application. This study evaluated the feasibility of reprocessing this material for reuse in successive cultivation cycles. The residual rice was transformed into a pressable formulation and used as a substrate for a new cultivation cycle of T. harzianum. Spore production, cell viability, physicochemical properties, and the effect of sodium bentonite as an additive to enhance productivity were assessed. Among the main findings, the formulation of residual rice supplemented with 2% bentonite achieved a maximum yield of 1.4 × 10⁹ spores per gram of dry substrate, a level comparable to fresh parboiled rice (2.2 × 10⁹ spores per gram of dry substrate), while maintaining the viability of the microorganism cultivated on the residue. Elemental analysis (CHN) revealed carbon and nitrogen contents similar to those of fresh rice, indicating that additional nutritional supplementation was unnecessary. Overall, the results demonstrate that the reuse of cultivated rice is technically feasible and represents an effective strategy for reducing costs and enhancing sustainability in the production of Trichoderma-based biopesticides, while also contributing to the valorization of agro-industrial residues in biofactories.