Abstract
Working with conventional microorganisms for bioconversion of industrial substrates is a challenge. In this sense, has been studied the possibility of replacing the conventional microorganisms with new strains prospected from specific environments. In the case of the dairy, the cheese whey is considered the main by-product, with lactose being its highest concentration constituent (about 90 % of the organic load). This carbohydrate is produced at a high and constant rate by the dairy industry each year. In this sense, is important to have viable alternatives to convert the lactose, available as a residue form, into value added products. The objective of this study was to select and evaluate the fermentative potential of strains prospected from the dairy industry, evaluating their kinetic parameters of growth, specific substrate consumption and formation of metabolites. The strains were cultivated in mineral medium with and without supplementation for the biochemical test. And The selected strains were grew in 250 mL Erlenmeyer flasks, pH 6.0 and lactose, glucose or galactose as the sole carbon source (10 g L-1) at 30 °C. The isolated were able to grow and produce ethanol in cultivation with lactose, glucose and galactose. In addition, less expressive growth was observed when galactose was used as carbon source. It was observed that when compared to glucose, some strains shows grown in lactose presented specific maximum growth rates (µmax) equal to or greater than those presented with glucose. This allows affirming that these strains are promising in the use of lactose as carbon source, since it efficiently metabolizes a disaccharide as much as it does with a monosaccharide. The characteristic of the studied strains of convert lactose efficiently reveals their potential for residue treatment applications.
