Optimized production and properties of thermostable alkaline protease from Bacillus subtilis SHS-04 grown on groundnut (Arachis hypogaea) meal

Folasade M Olajuyigbe

doi:10.4236/aer.2013.14012

Abstract

Production of alkaline protease from Bacillus subtilis SHS-04 was investigated under different fermentation conditions involving low-cost substrates with the aim of optimizing yield of enzyme. Maximum enzyme production (1616.21 U/mL) was achieved using groundnut meal (0.75%) as nitrogen source and 0.5% glucose as carbon source at 48 h cultivation period, pH 9, 45 ° C and 200 rpm. The yield was 348% increase over comparable control samples. The alkaline protease had optimum temperature of 60 ° C and remarkably exhibited 80% relative activity at 70 ° C. It was highly thermostable showing 98.7% residual activity at 60 ° C after 60 minutes of incubation at pH 9.0 and was stable in the presence of organic solvents studied. These properties indicate the viability of the protease for biotechnological and industrial applications. The optimized yield of enzyme achieved in this study establishes groundnut meal as potential low-cost substrate for alkaline protease production by B. subtilis SHS-04.

Highlights

Proteases constitute one of the most important groups of global industrial enzymes accounting for about 60% of the total enzyme sales [1]
This isolate was identified as B. subtilis in the Biotechnology Unit of the Federal Institute of Industrial Research, Lagos, Nigeria based on methods described in Bergey’s Manual of Systematic Bacteriology [14] and maintained on nutrient agar slants stored at 4 ̊C
Protease production started in the exponential phase corresponding with growth of organism and optimum production of 464.5 U/ mL was evident at 48 hour which was the late exponential phase of B. subtilis SHS-04

Summary

Introduction

Proteases constitute one of the most important groups of global industrial enzymes accounting for about 60% of the total enzyme sales [1]. Enzyme production by any organism is influenced by many factors such as pH, incubation temperature, incubation time, growth rate of culture and medium composition [4]. Reducing the cost of enzyme production by optimization of fermentation medium and process parameters is the major goal of basic research for industrial applications [6]. To this extent, the search for inexpensive carbon and nitrogen sources such as agricultural residues and marine by-products for use in media composition for protease production has been continuous

Methods

Results

Conclusion