DETERMINING THE POTENTIAL OF SUBMERGED FERMENTATION ON WHEAT BRAN FOR PRODUCTION OF XYLANASE

Abstract

Utilization of agro-industrial byproducts represents a way to broaden the palette of products derived from the less attractive and usually cheaper sources. The underutilized agroindustrial byproducts have attracted attention in recent years due to their effect on the environment. Wheat bran (WB) represents a byproduct of wheat industry and is a good source of fiber. Valorization of industry byproducts leads to reduction in production cost of enzymes due to high expenditure of expensive substrates required for microbial growth during the production process. Hydrolytic enzyme xylanase which transforms xylan into xylose is possible to produce using various microbial strains. Production of xylanase was investigated via submerged fermentation by Penicillium chrysogenum using a defined fermentation broth supplemented with adequate amount of WB (1 and 2.5% (w/v)). Submerged fermentation was carried out in a shaking incubator (100 rpm, 30 °C, n=2) over the course of 10 days. Crude enzyme samples were investigated each day for xylanase enzyme activity via 3,5-dinitrosalicylic acid (DNS) assay for reducing sugars using 1% (w/v) beechwood xylan solution in 50 mM Sodium Citrate buffer, pH 5.0 at 37 °C. Maximum activity was achieved on the 4th (1% (w/v) WB) and 5th (2.5% (w/v) WB) day of fermentation, 3.93±0.31 IU/ml and 4.48±0.067 IU/ml, respectively. pH (4–10) and temperature (25–60 °C) optima were determined via DNS method, and the optimal conditions were determined to be pH 5.0–5.5 and 37 °C. The influence of the addition of different metal ions and reagents on the enzyme activity was determined. The most beneficial effect was noted for the addition of MnCl2 and dithiothreitol. The increase of enzyme activities recorded was 22–29% for MnCl2 and 53–59% for dithiothreitol. It was concluded that P. chrysogenum can be further exploited in an enzyme production optimization process to increase xylanase activity.