Produção, purificação e caracterização de β-galactosidase a partir de Enterococcus faecium utilizando liquido metabólico de microalgas em meio de cultura comercial

Abstract

β-galactosidase commonly known as lactase, stands out as one of the most important enzymes used in food processing. Conventionally, its main application has been the hydrolysis of lactose in dairy products. One of its main sources are lactic acid bacteria, such as Enterococcus faecium, known for its ability to grow in different types of culture media. However, a large-scale production of these product generates high culture medium costs, leading to the search for alternatives for a total or partial replacement of that. The metabolic liquid of photosynthetic microorganisms can be an option due to the amount of vitamins, sugars and proteins present in the medium, which can be reused for the microorganism growth and bioactive production. The aim of this work was avaluate the production, purification and characterization of β-galactosidase from E.faecium using culture supernatant of the microalgae in commercial culture medium. Initially, a selection of the best alternative medium was performed using three microalgae supernatant (Chlorella vulgaris, Dunaliella tertiolecta and Scenedesmus sp) with different concentrations in commercial medium, then the best medium was submitted to the experimental design with response surface analysis aiming of optimizing the production conditions of the enzyme, through the following variables: pH, temperature, culture time and lactose concentration. The results showed that the medium containing C.vulgaris supernatant was the best in the production of the enzyme. The higher β-galactosidase activity was 30.83 U/ml with variables pH 8, 5% lactose concentration and temperature of 31°C. β-galactosidase was purified using ion exchange chromatography and molecular weigth was determinated by SDS- PAGE eletrophoresis. The purified fold was 3,05 with 7,02% of yield. The purified enzyme was then characterized aiming its industrial uses with maximal activity at 40°C and pH 7.0. When tested for stability, the enzyme keeping active for 45 min at 30 °C and optimum pH. These results indicate that β-galactosidase of E.faecium showed potential industrial application from low cost residue.