On-Site Production of Enzymatic Cocktails Using a Non-conventional Fermentation Method with Agro-Industrial Residues as Renewable Feedstocks

Abstract

Agro-industrial residues have great potential as low-cost feedstocks for production of hydrolytic enzymes, which play a key role in the economics of cellulosic ethanol production. The goal of this research was to add value to agro-industrial byproducts such as wheat bran (WB), soybean bran, and sugarcane bagasse [either untreated (SCB) or pretreated (SCBp)] by using these materials for on-site production of enzymes employing a non-conventional solid-state and submerged fermentation method. The results were compared to conventional submerged fermentation, and three enzymatic cocktails were selected for use in SCBp hydrolysis. The non-conventional method was successfully validated for enzyme production using all the feedstocks. Compositional analysis and FTIR spectra showed the advantages of using WB, rather than SCB, due to its lower C:N ratio and lower contents of lignin and phenolic derivatives. The use of a WB:SCB mixture resulted in endoglucanase production that was up to 91 % higher than achieved using SCB alone. The best hydrolysis performance was achieved with the WB enzymatic cocktail, and the mixture of WB:SCBp resulted in cocktails with performance 51 % higher than cocktails produced with SCBp alone. The non-conventional on-site enzyme production using agro-industrial byproducts could potentially contribute to the implementation of large-scale 2G ethanol plants.