Growth of Aspergillus niger and Trichoderma reesei from sugarcane bagasse: microbial consortium for biotechnological processes development to production of citric acid and ethanol

Abstract

Solid-state cultivation (SSC) is characterized by microbial growth on solid supports, in many cases agroindustrial by-products, in limited water conditions. Due to these characteristics, filamentous fungi are micro-organisms most frequently used for obtaining the most diverse byproducts. The use of mixed cultures or, in this case, fungal consortia, presents as main advantage complementation in terms of hydrolytic enzymes, which leads to better utilization of the molecules on the solid support. Citric acid and ethanol are important commercial bioproducts used in various sectors of the economy, which could be obtained by a sequential process CES-fermentation from bagasse sugarcane impregnated with vinasse, minimizing costs from two generated by-products in the same industrial platform. In this context, the present study aims to assess the CES consortium of Aspergillus niger and Trichoderma reesei for the production of citric acid from sugarcane bagasse and vinasse, with subsequent introduction of yeast to obtain ethanol via conversion of glucose present the fungal extract. Whereas previous work of our research group at the Center for Agricultural Sciences of UFSCar indicate the feasibility from type SSC, this proposal aims the use of microbial consortia and obtaining ethanol as a "proof of concept" of the use of SSC´s residual glucose, leading to a better use of structural polysaccharides of sugarcane bagasse. Thus, our research hypothesis is the production of citric acid via SSC from sugarcane bagasse and vinasse with high yield and subsequent production of ethanol from fungal extract with less interference inhibitors, common in acid hydrolysis lignocellulosic material. The academic study back up the assessment of a SSC unconventional at different scales, adding two by-products generated in the same industrial platform and using mixed microbial cultures. It is also worth noting that were not found in the works literature on the use of wastewater as impregnating solution particles for SSC, nor the use of microbial extract obtained for driving other biotechnological processes, suggesting the innovative nature of the research. In addition, there is a regional aspect highlighted by the use complement different typical agro-industrial by-products of the industrial sector of the Araras region and CCA/UFSCar. (AU)