Production of extracellular alkaline protease under Solid State Fermentation (SSF) by Bacillus megaterium NCIM-2087 was tested on substrates of different agrowastes, including soy cake, wheat bran, rice bran and green gram husk, with a pH ranging from 8-11, particle size above 7 mm, inoculum levels 1 mL to 5 mL/10 g of substrate, incubation time from 12 to 96 h and relative moisture levels from 60% to 140%. The peak alkaline protease produced by B. megatarium NCIM-2087 was observed in the soy cake substrate (5961.0 U/g), at pH 9, particle size 4-18 mm, 3 mL/10 g of substrate inoculum level, 60 h of incubation time and at 100% relative moisture level.

Proteases are the essential constituents of all living organisms on earth, including prokaryotes, fungi, plants and animals, due to their role in many physiological and pathophysiological processes. Proteases constitute two-thirds of the total enzymes used in various industries, and this proportion is expected to increase substantially by the year 2005 (Gupta et al., 2002). Proteases from microbial source account for approximately 40% of the total enzyme sales worldwide (Godfrey and West, 1996).

Proteolytic enzymes can be classified as acidic, neutral and alkaline proteases based on their optimal pH. Acidic proteases are used in meat tenderization, production of fermented foods and also in acidic clearing compositions (Rao et al., 2007). Neutral and alkaline proteases are used in detergent and leather tanning industries due to their eco-friendly nature (Rao et al., 1998). Alkaline proteases have numerous applications in food industries (Kalisz, 1988; and Outtrup and Boyce, 1990), silver recovery from x-ray films (Fujiwara et al., 1991) and several bioremediation processes. In a recent study, Puri (2001) reported degumming property in silk by alkaline protease from Bacillus sps.

Most of the early studies on alkaline proteases were on Submerged Fermentation (SMF). Solid State Fermentation (SSF) is advantageous over SMF due to its low investment, simple energy needs and low contamination rates. Additionally, low cost of substrates, such as agroindustrial wastes (soy cake, wheat bran, sugar cane bagasse, rice bran, etc.), further reduces the production cost (Mitchell et al., 2002). However, SSF processes present some limitations including optimal growth of a few species of microorganisms under reduced moisture levels. The literature review shows an extensive use of filamentous fungal species in SSF due to their ability to grow well under low moisture conditions (Germano et al., 2003). However, there are a few reports on the production of enzymes by SSF using bacteria in the recent years (Yang and Wang, 1999; and Uyar and Baysal, 2004).

Biotechnology Journal, Bacillus Megatarium, Alkaline Protease, Soy Cake, Wheat Bran, Rice Bran, Green Gram Husk, Particle Size, Inoculum Level, Incubation Time, Moisture, Solid State Fermentation, SSF, Optical Density, OD, National Chemical Laboratory, NCL, Total Solubility of Nutrients, TSN, Microbial Culture.