Oxalic acid as the main molecule produced by trichoderma asperellum MG323528 fermented on corn stover based medium

Abstract

Background and Objective: Organic acids have several pharmaceutical, food, agricultural and medical applications. Corn stover represents a serious environmental problem. The present study investigated the bio processing of such readily available low-cost biomass with microorganism into valuable organic acids that expected to neutralize the negative impact on the environment and minimize the production costs. Materials and Methods: A novel cellulolytic Trichoderma asperellum MG323528 was selected as a new corn stover decomposer that could transform it into various bio-products. The fungus was incorporated in corn stover-based medium for the production of organic acids. The Box-Behnken experimental design was applied to maximize the total organic acids production especially oxalic acid. Results: The optimum composition of solid-state fermentation medium was found to contain17.83 mg P from rock phosphate, 5.61 mg N from (NH4)2SO4 and 9.84 mg MgSO4·7H2O per 1 g of corn stover, yielding a total of 209.11±1.20 mmol organic acids. According to the HPLC screening, the main organic acids detected in the fermented corn stover was oxalic acid, representing about 78% of the total organic acids, in addition to minor amounts of citric, formic, salicylic and ascorbic acids. Conclusion: This kind of homo-fermentation could be considered for large-scale production of oxalic acid on an economic medium of CS using the promising T. asperellum MG323528 strain.