Produção de bioetanol por co-cultivo de fungos.

Abstract

The great challenge for second generation ethanol is to find strategies that allow the bioconversion of polysaccharides in lignocellulosic materials in simple carbohydrates. In this regard, the knowledge of the biotechnology field has been acting on the development process configurations that operate on performance efficiency of fermentable sugars for bioethanol production. The aim of the present study was to develop a process for second generation ethanol production from lignocellulosic biomass using co-cultivation fungi. Two growing conditions were addressed to enhance the use of microorganisms involved in this process. The first step was in aerobic condition, driven the CDSA12 filamentous fungus to synthesize enzymes that hydrolyze polysaccharides to fermentable sugars. At the second stage, in anaerobic condition JP1 Saccharomyces cerevisiae metabolize carbohydrates converted by cellulolytic enzymes producing ethanol. The broth was constituted by the in natura bagasse at Experiment 1 and by hydrothermally pretreated bagasse at Experiment 2. The results show that the ethanol production process by fungi co-culture is effective to reduce the costs connected to the use of commercial enzymes for the hydrolysis of cellulose. The CDSA 12 fungus was capable to secrete the enzyme carboxymethylcellulose (CMCase) producing the same enzymatic activity about 0.465 and 0.54 U.mL-1 at Experiments 1 and 2, respectively. Throughout the entire process, the pH remained in the optimum range to produce CMCase when synthesized from filamentous fungi. The hydrolysates polysaccharide (Reducing Sugar - RS) presented a maximum concentration of 18.89 and 18.83 g.L-1 at Experiments 1 and 2, respectively. At Experiments 1 and 2 the yield relating to conversion of cellulose to ethanol was 0.341 and 0.182 g.g-1, while ethanol productivity was 0.244 and 0.391 g.L-1.h-1, respectively. Therefore, the configuration of the bioethanol production process by fungi co-cultivation is feasible to reduce the operating costs of the production system.