Comparative Evaluation of Agroindustrial Byproducts for the Production of Alkaline Protease by Wild and Mutant Strains of Bacillus subtilis in Submerged and Solid State Fermentation

Hamid Mukhtar,Ikramul Haq

doi:10.1155/2013/538067

Hamid Mukhtar, Ikramul Haq

Open Access

https://doi.org/10.1155/2013/538067

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Abstract

The present study describes the screening of different agroindustrial byproducts for enhanced production of alkaline protease by a wild and EMS induced mutant strain of Bacillus subtilis IH-72EMS8. During submerged fermentation, different agro-industrial byproducts were tested which include defatted seed meals of rape, guar, sunflower, gluten, cotton, soybean, and gram. In addition to these meals, rice bran, wheat bran, and wheat flour were also evaluated for protease production. Of all the byproducts tested, soybean meal at a concentration of 20 g/L gave maximum production of the enzyme, that is, 5.74 ± 0.26 U/mL from wild and 11.28 ± 0.45 U/mL from mutant strain, during submerged fermentation. Different mesh sizes (coarse, medium, and fine) of the soybean meal were also evaluated, and a finely ground soybean meal (fine mesh) was found to be the best. In addition to the defatted seed meals, their alkali extracts were also tested for the production of alkaline protease by Bacillus subtilis, but these were proved nonsignificant for enhanced production of the enzyme. The production of the enzyme was also studied in solid state fermentation, and different agro-industrial byproducts were also evaluated for enzyme production. Wheat bran partially replaced with guar meal was found as the best substrate for maximum enzyme production under solid state fermentation conditions.

Highlights

Microorganisms represent an excellent source of proteolytic enzymes owing to their broad biochemical diversity and their suitability to genetic manipulation
The random mutagenesis of the wild strain of Bacillus subtilis was carried out using ethyl methane sulfonate (EMS) for enhanced production of proteases according to the protocols developed in our labs
Of all the agroindustrial byproducts evaluated, soybean meal was found to be the best substrate for production of alkaline protease showing a yield of 5.74 ± 0.26 U/mL and 11.28 ± 0.45 U/mL

Summary

Introduction

Microorganisms represent an excellent source of proteolytic enzymes owing to their broad biochemical diversity and their suitability to genetic manipulation. Microbial proteases account for approximately 40% of the total worldwide enzyme sales [1]. Proteases from microbial sources are preferred to the enzymes from plant and animal sources, since they possess almost all the characteristics desired for their biotechnological applications. The microbial enzymes are not subjected to any of the production and supply limitations. Alkaline proteases are produced by a large number of bacterial species; Bacillus species possess remarkable biotechnological value due to their nonpathogenicity of various species and the ability to produce extracellular protease in large amounts. Protease production has been reported by alkalophilic Streptomyces spp. Protease production has been reported by alkalophilic Streptomyces spp. [10], Pseudomonas spp. [11], Photorhabdus spp. [12], Lactobacillus spp. [13], Alcaligenes faecalis [14], and Xanthomonas maltophilia [15]

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