Produção de proteases por Aspergillus ochraceus URM 604 obtidas por fermentação em estado sólido utilizando farelo de trigo e resíduo de café como substrato

Abstract

Proteases are enzymes of great commercial interest, since it has several industrial applications, such as the pharmaceutical, food, beverages and cleaning products. Among the organisms capable of producing these enzymes are filamentous fungi, having as advantages the possibility of secreting enzymes in the extracellular medium and growing on low-cost substrates. The Solid State Fermentation (SSF) is one of the recommended techniques in the cultivation of filamentous fungi, especially because it simulates its natural habitat, favoring their growth. Aiming the importance of proteases and the growing demand of the global market needs, it is necessary to search for new sources and better production methods. Thus, the objective of this research was to produce proteases by the filamentous fungus Aspergillus ochraceus URM 604 under SSF using substrates derived from the agribusiness, in 2³ factorial design. It was investigated the influence of the type of substrate (coffee residue, wheat bran and 1: 1 coffee + wheat bran), amount of substrate (3g, 5g and 7g ) and humidity (20, 40 and 60%) to determine the ideal conditions for protease production. Fermentation took place for 7 days at 30 °C and the metabolic extract was used for further analysis. For biochemical and physical analysis the protein activity, total proteins, temperature and optimal pH of the obtained enzyme were determined. When analyzing the influence of the variables adopted in the 2³ factorial design, only the type of substrate was a significant parameter. The best substrate was wheat bran, which showed a specific enzymatic activity of 218.27 U / mg under 3g of substrate and 60% humidity. The other conditions also showed high results when compared to the literature. The optimum temperature of the enzyme produced was 50°C and the optimum pH was pH 8-9 (alkaline protease). Thus, this research shows that the fungus A. ochraceus URM 604 has biotechnological potential for protease production under SSF using low-cost substrates such as coffee grounds and wheat bran, this being the first report for the species.