Estratégias de utilização de biomassas lignocelulósicas para produção de coquetéis enzimáticos por Penicillium ucsense S1M29 em cultivo submerso

Abstract

In the present work, four different lignocellulosic biomasses - sugarcane bagasse, elephant grass, eucalyptus/pine pulp and corn harvest residues - were evaluated for the production of cellulases and xylanases by Penicillium ucsense S1M29, in submerged culture. In stirred tank reactor, in a batch regime, the use of sugarcane bagasse and corn harvest residues proved to be more promising, resulting in higher activities of FPA, endoglycanases, exoglycanases, β-glucosidases and xylanases. In fed-batch, increases in enzymatic activities were observed, except for eucalyptus/pine pulp. Sugarcane bagasse doubled FPA activity, while for elephant grass and corn harvest residue, this increase was 2.7 times. For eucalyptus/pine pulp there was a marked decrease in activity, proving its inefficiency for use in enzyme complex production in a submerged process. Increases in activity were greater for β-glucosidases when produced using elephant grass (8.6 times) and sugarcane bagasse (4.6 times). The stability and optimal activity of crude enzyme extracts from P. ucsense produced in different biomasses were also evaluated, and compared to two controls – enzymes produced in commercial cellulose and a commercial enzyme cocktail Celluclast®. The higher activities related to enzymes produced in lignocellulosic biomasses were observed at temperatures between 60 and 70°C, and pH varying between 4 and 5.5. Regarding thermostability and stability at different pH values, the enzymes were more stable, after 72h, at pH between 4 and 5. The temperatures that resulted in greater stability after 72h were between 40 and 50°C, for the majority of the enzymes evaluated, with emphasis on endoglycanases and β-glucosidases produced in corn harvest residues, which were more stable at 60 and 65°C, respectively. Regarding the use of different crude extracts in the hydrolysis of lignocellulosic biomass, the enzymes proved to be efficient when compared to the commercial Celluclast® cocktail. The results obtained are promising for the development of large-scale enzyme production processes using lignocellulosic waste, since enzyme titers close to or higher than those produced with commercial cellulose were achieved, and the enzymes produced have desirable characteristics for a possible commercial application of these cocktails. Another important factor is that the development of such a process can help reduce the costs of cellulolytic enzymes, and consequently in the production process of second-generation ethanol, as well as other microbial metabolites of economic interest. [resumo fornecido pelo autor]