Abstract
The increase in agricultural practices has necessitated the judicious use ofagricultural wastes into value added products. In this study, an extracellular, organic solvent and oxidant stable, serine protease was produced by Aspergillus flavusMTCC 9952 under solid state fermentation. Maximum protease yield was obtained when the strain was grown under wheat bran and corn cob mixture (1:1) incubated for 48 h at pH 9.0 and temperature 37°C with 50% of initial moisture content. The partially purified enzyme showed wide range of pH optima (8.0-12.0) and pH stability (7.0-12.0), whereas, optimum temperature was 40°C and was stable over a wide range of temperature 30-45°C. The protease was extremely stable towards several organic solvents. The enzyme retained 80% of its original activity in the presence of non ionic and ionic surfactants and 100% with 10% H2O2 after 1 h of incubation at 30°C. In addition, the enzyme showed excellent compatibility with some commercial powder detergents. The compatibility of our protease with several detergents, oxidants and organic solvents suggests its possible use in detergent industry and peptide synthesis. Key words: Alkaline protease, solid state fermentation, PMSF, organic solvent.
Highlights
Proteases are commercially important enzymes (Ferrero et al, 1996; Kumar et al, 1999) which account for approximately 60% of global industrial enzyme sales (Rao et al, 1998)
Aspergillus, Penicillium and Rhizopus are widely used for protease production since several species of these genera are regarded as safe (GRAS) strains (Pandey, 1992)
In view of the above, we report here the production of alkaline protease by Aspergillus flavus MTCC 9952, with an aim to find a set of culture conditions using agro industrial wastes and characterize the properties of partially purified enzyme leading to the development of detergent formulations and for peptide synthesis in non aqueous media
Summary
Proteases are commercially important enzymes (Ferrero et al, 1996; Kumar et al, 1999) which account for approximately 60% of global industrial enzyme sales (Rao et al, 1998). Proteases occur widely in plants and animals, but commercial proteases are produced exclusively from microorganism (Chutmanop et al, 2008). Aspergillus, Penicillium and Rhizopus are widely used for protease production since several species of these genera are regarded as safe (GRAS) strains (Pandey, 1992). Aspergillus has ideally been an organism of choice for bulk production of industrial enzymes, as the fungi can be grown on relatively inexpensive agricultural. Enzyme production can be carried out by both submerged fermentation (SmF) and solid-state fermentation (SSF), the latter being a technique of choice (Pandey et al, 2001; Sandhya et al, 2005). Alkaline serine proteases (EC 3.4.21) are active and stable at neutral to alkaline pH (7-12), and find extensive applications in protein chemistry and protein engineering as well as in industries such as detergents, leather, protein recovery, meat tenderization etc. (Lauer et al, 2000; Johnvesly and Naik, 2001)
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