Effects of carbon and nitrogen sources on production of proteases by Bacillus subtilis IC-5

The effects of various carbon and nitrogen sources were evaluated on production of proteases by Bacillus subtilis IC-5. Both type and concentration of carbon and nitrogen sources influenced the production of proteases. Among the carbon sources glucose was found to be the most effective. It gave maximum production at 2% w/v concentration i.e., 1875 and 950 U/ml, alkaline and neutral protease, respectively. The response of Bacillus subtilis IC-5 towards synthesis and excretion of enzymes varied with the type of nitrogen sources. The addition of organic nitrogen sources to basal medium repressed the synthesis of proteases while the addition of inorganic nitrogen source such as sodium nitrate was found to be the best stimulating for alkaline and neutral protease synthesis. Sodium nitrate enhanced the production up to 62.40 and 10.52% of alkaline and neutral protease, respectively against w.r.t. control. Introduction Industrial enzymes are obtained from three major sources i.e., plant, animal and microorganisms. The extraction of enzymes from plant or animal source is limited and seasonal in case of plant source. However, production of enzymes by fermentation process is unlimited and can be produced round the year. Proteolytic enzymes are ubiquitous in occurrence, being one of the largest and most important groups of enzymes which accounts for about 30% of total worldwide production (Horikoshi 1996) and about 60% of sale (Beg et al. 2003). The extracellular proteases have commercial value and find multiple applications in various industrial sectors. The detergent industry has emerged as one of the major consumers of hydrolytic enzymes working at higher pH (Adinarayana et al. 2003). It is used as cleansing additives in detergents to facilitate the release of proteinacious materials in stains due to grime, blood, milk, etc (Olajuyigbe and Ajele 2005). Proteolytic enzymes applied in other industries are food, pharmaceutical, leather, silk and recovery of silver from used X-ray films (Prakasham et al. 2002). Proteases are produced by a wide range of microbes i.e., bacteria, mould and yeast (Gupta et al. 2002). Among bacterial strains of Bacillus sp. dominate the industrial quarters. The extracellular protease production by microorganisms is greatly influenced by media components especially carbon and nitrogen sources being the main energy and growth promoting factors (Kole et al. 1988). The selection of cost effective nutrients (carbon and nitrogen) is of utmost desire for optimum production of enzymes (Varela et al. 1996). In present study, the effects of carbon and nitrogen sources and their concentrations on production of proteolytic enzymes by Bacillus subtilis were investigated. *Author for correspondence: . Department of Botany, University of Balochistan, Quetta, Balochistan, Pakistan. Department of Zoology, University of Balochistan, Quetta, Balochistan, Pakistan.