Bioprocessing of Agricultural Wastes as Optimised Carbon Source and Optimisation of Growth Conditions for Xylanase Production by Aspergillus brasiliensis in Agitated Solid State Fermentation (Ssf)

Abstract

Objective: Xylanase has been involved in many industrial applications especially in the pulp and paper, baking, detergent as well as food and beverage industries. This enzyme is produced by various microorganisms, mainly from fungal species. Therefore, in this study, Aspergillus brasiliensis ATCC 16404 was investigated for the optimum xylanase production under agitated solid state fermentation (SsF) using different agricultural wastes as alternative inexpensive carbon source. Methods:A. brasiliensis was cultured in 10 g agricultural waste with addition of 2% yeast extract as the nitrogen source up to 120 h of SsF to elucidate xylanase production. Effect of various agricultural wastes such as wheat bran, rice bran, soybean hulls, barley husk, maize and palm kernel cake (PKC) on xylanase activity were enumerated in a stepwise manner, where one parameter was investigated at a time approach to obtain the optimum carbon source for the maximum xylanase production by A. brasiliensis. Thereafter, growth temperatures from 25 to 45°C, initial medium pH from 4 to 10 and agitation speeds of 50 to 200 rpm were also elucidated to determine the optimum growth conditions for the maximum production of xylanase by A. brasiliensis.Results: Based on our results, the highest xylanase activity of 7.30 ± 1.93 U/mL was obtained using wheat bran as the prime carbon source with the initial medium pH 6.5 at 30°C at the agitation speed of 150 rpm. Conclusion:Thus, in our study, the maximum xylanase production by A. brasiliensis using solid state bioprocessing of wheat bran as the carbon source was achieved with the addition of 2% yeast extract as the nitrogen source under the optimum growth conditions of 30°C with medium pH 6.5 at 150 rpm.