Rice Recycling: A Simple Strategy to Improve Conidia Production in Solid-State Cultures

Abstract The aim of this work was to propose a strategy to revalorize the residual rice remaining at the end of a conventional conidia production process in solid-state culture. The proposal involved the reuse of rice in successive cycles of conidia production. As a result, the reuse of rice in successive cycles significantly increased the production and productivity parameters of the fungal strains Trichoderma asperellum Th-Th4 (3) and Metarhizium robertsii Xoch-8.1. Conidia production in T. asperellum Th-Th4 (3) increased from 1.0×109 to 4.9×109 con/gds, while in M. robertsii Xoch-8.1, this parameter increased form 5.7×108 to 3.8×109 con/gds. In addition, this strategy did not affect the viability of the conidia produced using recycled rice relative to the conidia produced using fresh substrate (unrecycled rice). The proposed recycling approach was simple, and completely free of extra -drying, -sterilization, and -reinoculation steps. The technique required minimal operational intervention and thus can be easily adopted by small bio-factories or self-supply units.