Journal of School of Public Health and

  Background and Aim: Xylanases are widely used in various food industries, including livestock and poultry feed industries, the pulp and paper industry, as well as the pharmaceutical industry. Several strains of microorganisms are capable of producing this enzyme by different mechanisms, Bacilliaceae being one of its important sources at the commercial scale. The culture medium for xylan is expensive and, therefore, it is not economical to use in producing xylanase by Bacillus subtilis S7e. The purpose of this study was to explore the possibility of using industrial-agricultural wastes as a source of carbon and nitrogen in submerged fermentation, for producing xylanase in amounts higher than that which can be produced by xylan culture (10048 U/).

  Materials and methods: The indigenous strain of Bacillus subtilis S7e was cultured in the xylan medium, followed by incubation at 30°, 37° and 40° C. Then the nitrogen sources (rapeseed meal, soybean meal, tomato seeds, tea seeds, peptone, Vinas alcohol, casein, and ammonium sulfate) and carbon sources (molasses, wheat bran, rice bran, rice industry waste, gluten waste, malt waste, whey powder, and bagasse) were substituted for the meat and yeast extracts and the xylan culture medium, respectively.

  Results : The maximum enzyme activity was observed at 30° C after 48 hours of incubation (6183U/l). Rapeseed meal with an enzyme activity of 10048U/l and molasses with an enzyme activity of 3759U/l were found to be the best nitrogen and carbon sources for Bacillus subtilis S7e , respectively.

  Conclusion: Based on the findings of this study, f rom an economic point of view, agricultural-industrial wastes (rapeseed meal and molasses) are an excellent substitute for the more expensive culture media currently in use for producing the enzyme xylanase.