Biotechnological valorization of rice waste from Trichoderma production through the development of a streptomyces-based biological soil conditioner

Abstract

Sustainable soil management is vital for maintaining agricultural productivity while mitigating the environmental impacts of intensive pesticide use. This study evaluated the use of rice waste generated during Trichoderma asperelloides production as a substrate for the cultivation of Streptomyces sp. BEI-18 A through solid-state fermentation to obtain a biological soil conditioner. The rice waste from Trichoderma production (RWTP) underwent solid-state fermentation (SSF) for seven days, and the product was characterized according to the Brazilian Normative Instruction No. 35/2006 for soil conditioners and amendments. Biological analyses included colony-forming unit (CFU) counts, enzymatic activity (β-glucosidase and arylsulfatase), and respirometry. The conditioner was also applied to soil at different rates in maize (Zea mays L.) pot experiments to assess its effects on soil biological parameters. The application of the biological soil conditioner increased microbial abundance, enzymatic activity, and CO₂ release compared to the control, increasing β-glucosidase classification from moderate to adequate. Although physicochemical parameters did not meet the criteria for physical or chemical classification, the material met the requirements for classification as a biological soil conditioner. The results indicate that rice waste from T. asperelloides production can be reused as a substrate for producing bioinputs capable of enhancing soil biological activity. Rice waste from Trichoderma production was reused as substrate for Streptomyces growth. Solid-state fermentation produced a Streptomyces-based biological soil conditioner. The biological soil conditioner enhanced microbial activity, β-glucosidase, and CO₂ release in soil. Valorization strategy promotes circular economy and supports UN SDGs 2, 9, 12 and 15.