Seleção de fungos filamentosos produtores de lipases com potencial de aplicação para a produção de biodiesel por catálise enzimática

Abstract

Microbial lipases are very prominent biocatalysts due to their ability to catalyze a wide variety of reactions in aqueous and non-aqueous media. In this work, the selected filamentous fungi were isolated from leaves decomposed in the Buritizal River, located in Taquaruçu in the State of Tocantins and identified with the ITS gene, were screened for lipase production with hydrolytic activity and esterification. Fusarium solani showed the highest production of lipase, with 2.37 U/mL and esterification activity of 0.07 U/mL using medium 3 containing: KH2PO4 1.00 gL-1, MgSO4 H2O 1.123 gL-1, CuSO4, 06 gL-1. Supplementation of this culture medium with organic nitrogen sources increased lipase production in (461.29%) 3.48 U/mL using tryptone and (419.35%) 3.22 U/mL using yeast extract, all the results were always analyzed with reference to the initial activity of the fungus 0.62 U/mL. Among the vegetable oils evaluated in the work, degummed cotton oil induced lipase production in (1212.90%), 8.14 U/mL. A Plackett-Burman factorial design with 15 experiments was conducted to evaluate the influence of seven factors on the production of lipases by F. solani. The factors investigated were: peptone, tryptone, yeast extract, calcium chloride, potassium phosphate, magnesium sulphate and copper sulphate, which were kept in five fixed variables containing: cotton oil, pH, temperature, agitation and time and as a response to enzymatic activity. The concentration of tryptone, calcium chloride and magnesium sulphate had a significant effect (p < 0.10) on lipase production and were studied consecutively through a complete DCCR (rotational composite) design, in order to optimize production of the fungus F. solani lipases. After optimization using DCCR, maximal lipolytic activities of 24.84 U/mL were obtained with the use of 10 gL-1 tryptone, 3.50 gL-1 calcium chloride and 0.50 gL-1 magnesium, 1 gL-1 potassium phosphate and 1% soybean oil. The statistical model showed a correlation of 85.67% with the experimental data. The biochemical characterization of lipase showed that the enzyme has a better performance at pH 7 at a temperature of 40 ° C, where the statistical model showed a correlation of 94.15% with the experimental data. In this way the lipases produced by F. solani have potential for application and use in the production of biodiesel, and can be an alternative to the conventional processes in the production of biofuels.