ORIGINAL PAPER Optimization of novel hyperthermostable b amylase production by Bacillus subtilis DJ5 using solid agroresidual substrates A. Poddar • S. C. Jana Received: 17 January 2012 / Revised: 3 January 2013 / Accepted: 16 March 2013 / Published online: 17 April 2013 Ó Islamic Azad University (IAU) 2013 Abstract Eight different low cost starchy agroresidues namely Barley (B), Wheat bran (WB), Sattu (S), Rice powder (RP), Corn flour (CF), Rice husk (RH), Yellow peas split (YPS) and arrowroot (A) were used for solid culturing of Bacillus subtilis DJ5 for production of novel hyperthermostable b amylase. Various process parameters like initial moisture content, inoculum load, medium pH and incubation temperature affecting enzyme production were optimized to ensure maximum enzyme yield. Only 10 % inoculums load and medium pH of 6.9 was found sufficient to achieve maximum enzyme production in all substrates in a decreasing order, B [ WB [ S [ RP [ CF [ RH [ YPS [ A. Optimum b amylase production was highly dependent on initial moisture content of sub- strate as observed from varying requirement of moisture for different substrates. Only 50 % moisture was sufficient for maximum enzyme production of 84.29 U/gdm in CF. For B, RH, YPS, and A 60 % initial moisture resulted in higher production of 120.34, 35.19, 26.59, and 21.58 U/ gdm, respectively, at 37 °C. However, for S and RP higher (70 %) moisture content allowed 113.4 and 85.56 U/gdm enzyme production, respectively. Under optimized condi- tions, maximum b amylase production was observed after 25 h for A, YPS, RH, RP; 41 h for B, WB, CF, and 45 h for S. Keywords Agroresidues Á Barley Á Moisture content Á Wheat bran Introduction Advancement of science and technology in the agricultural field has successfully accumulated huge amount of crops and crop residues. Improper preservation and lack of proper management of these residues is posing a serious threat to the environment (Gustavsson et al. 2011). Beside human consumption, large parts are being used as cattle feed, power generation, still huge amount of crop residues are left unutilized (Parfitt et al. 2010). It must be managed in other ways to reduce wastage and environmental pol- lution. In a view to proceed in that direction, microbiolo- gists have successfully used solid state fermentation (SSF) to convert agroresidues into economically important value added products (Pandey et al. 1999; Pandey and Soccol 2000; Kim and Dale 2004; Haddadin et al. 2001) that not only the helps in waste management (Pandey et al. 2000a, b, c), but also strengthen economy of a country. History tells us that SSF technology was initiated early with the civilization as the process is less complicated, requires minimum process monitoring. SSF process is carried out on a non-soluble material that acts both as physical support and as source of nutrients in absence of free flowing water (Pandey 2003). SSF offers numerous advantages over submerged fermentation (SmF) in pro- cessing of agro-industrial residues as it has low capital investment, lower levels of catabolite repression (Gonza ´lez and Torres 2006) and end product inhibition, low waste- water output, better product recovery, and high quality production (Lonsane et al. 1985) and are environmentally friendly. During the last decade, an increased attention was paid to the use of various agro-industrial wastes for amylase production using SSF (Alva et al. 2007). Amylases being the most important industrial enzymes have found a wide A. Poddar Á S. C. Jana (&) P.G. Department of Microbiology, Bidhannagar College (Govt. of West Bengal), EB 2, Salt Lake City, Kolkata 700064, West Bengal, India e-mail: subhasjana1959@gmail.com 123 Int. J. Environ. Sci. Technol. (2014) 11:1127–1134 DOI 10.1007/s13762-013-0275-3