Seleção de leveduras de frutos do cerrado tocantinense para produção de hidrolases e otimização de suas condições de cultivo

Abstract

Enzymes have an essential role in various segments, for example, in detergents, pharmaceuticals, textile and food industries. The identification of new microbial sources for production of enzymes is of great industrial interest, as well as the optimization of culture medium for production. The application of statistical approaches involving the Plackett- Burman and response surface methodologies are useful tools for understanding and optimizing interactions between the various parameters involved in the production of a particular enzyme. This study aimed to evaluate the enzymatic production potential of yeasts strains from babassu coconuts (Orbignya sp.), buriti palm (Mauritia flexuosa), tucumán (Bactris inundata), inajá (Attalea maripa) and macaúba (Acrocomia aculeata), typical fruits of the Cerrado in Tocantins. A total of 142 yeasts were tested for their ability to produce lipase, amylase, protease and pectinase in specific solid media at incubation time of 21 days at 35 °C. A total of 61 strains were positive for lipase, of which 28 (45.9%) had an enzymatic index (EI) ≥ 2. Only one yeast presented halo indicator of amylase production (EI = 1.57), and there were no positive results for pectinase and protease. Subsequently, the yeast coded with number 13, which obtained the best lipolytic activity on solid medium, was subjected to cultivation in liquid medium according to a Plackett-Burman experimental design followed by a rotational central composite design to optimize the enzyme production conditions. The best condition, with lipase activity of 41.45 U.mL-1, was found to be 10 g.L-1 of yeast extract, 10 g.L-1 peptone, 30 g.L-1 (NH4) 2SO4, 1 g.L-1 Tween 20, 1.5 g.L-1 MgSO4.7H2O, 0.7 g.L-1 KH2PO4 and 10 g.L-1of olive oil. When compared with buriti and babassu oils, the olive oil was the best inducer for the lipase production.