Production and Optimization of Alkaline Protease in the Solid-State Fermentation by Bacillus licheniformis

Introduction and Objectives: Proteases are enzymes that hydrolyze proteins by the addition of water across peptide bonds. Proteases are one of the most important groups of industrial enzymes used in pharmaceutical and food industry for peptide synthesis. These are used in leather industry for dehairing and as an additive of detergent formulation in detergent industry. Alkaline proteases are known to constitute 60-65% of the global industrial market among various types of proteases. The aim of this study was to production and optimization of alkaline protease in the solid-state fermentation by bacillus licheniformis. Materials and Methods: Bacillus Licheniformis PTCC 1595 was obtained from the Iranian Research Organization for Science and Technology (IROST). In this work, design of experiments (DOE) methodology using full factorial design was applied to evaluate the influence of different carbon sources (rice husk, rice bran, wheat bran), nitrogen Sources (urea, yeast extract, peptone, casein) and pH (7, 8, 9, 10) on Alkaline proteases production. The fermentation process was held at a temperature of 37 °C for 48 hours. Measurement of the enzyme activity was carried out by measuring optical density at 660 nm. Results: The highest alkaline protease activity (154.07 U/ml) was achieved when rice husk as carbon source, urea as nitrogen source, at pH 10.Conclusion: In the present study, the effect of different carbon sources, nitrogen sources and pH on alkaline protease production by bacillus licheniformis was studied. The results showed that rice husk, by-product of rice industry can be used efficiently for alkaline protease production under solid-state fermentation.

Keywords:

Alkaline Protease , Bacillus licheniformis , Solid-State Fermentation , Design of experiments