Abstract
Production of phytase by Aspergillus japonicus URM 5633 was investigated by solid state fermentation (SSF) using cassava bast as substrate. The effects of temperature, pH and initial moisture on phytase production were studied using a full factorial design 23. The maximum phytase activity was 174 U/g dry substrate. The optimum conditions for phytase production were pH 6.5 and 40% initial moisture at 26°C with 96 h of fermentation. A factorial design 22 was created to optimise phytase production, where the initial moisture and temperature were the variables studied. The parameters for phytase production were fixed at 30% initial moisture, 30°C and pH 5.5, and the maximum activity obtained was 183.1 U/g dry substrate. The effects of glucose concentration, nitrogen source type and nitrogen source concentration in phytase production was studied using the 23 factorial design. Nitrogen source concentration was significant for phytase activity and had a negative effect, indicating that smaller values increased enzyme activity. The optimum activity for phytase occurred at pH 3.6 and at an apparent optimum temperature of 60°C. Phytase was stable in the pH range of 2.4-3.0 at 30-70°C. The enzymatic activity increased significantly in the presence of FeSO4. Key words: Filamentous fungus, residue, enzyme, production, characterization.
Highlights
Brazil is one of the largest producers of cassava in the world
Fungi are important producers of extracellular enzymes and are relatively easy to grow in controlled environments (Santos, 2007)
Screening is often the first step to select microorganisms with characteristics intended for Industrial applications, which allows the characterization and selection of fungal strains with optimal enzyme production (Maciel et al, 2013)
Summary
Brazil is one of the largest producers of cassava in the world. The industrial process for the production of cassava derivatives generates large amounts of waste in the form of bark and bast. There is a high demand for use of industrial wastes as substrates to reduce the environmental impact and generate resources (Ferreira and Silva, 2011). Solid state fermentation (SSF) systems have generated much interest lately because they offer economical and practical advantages, including the use of agro-industrial residues as substrates for obtaining products with added value, higher concentration and improved recovery in.
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