Hooi Ling Ho and Stephanie Ak Sali
Objective: Xylanase production by Aspergillus species has become valuable and attractive due to its vast applications in pulp and paper, food and beverage, detergent and textiles industries. Xylanase is one of the hemicellulolytic enzymes that capable of hydrolysis of ß-1,4 xylans present in the lignocellulosic materials. Therefore, Aspergillus brasiliensis ATCC 16404 was used to investigate the maximum production of xylanase using various agricultural residuals in solid state fermentation (SsF).
Methods: SsF is the fermentation process of culturing microorganisms using humid solid substrates without emerging in culture broth. SsF has always been an attractive substitute of liquid culture for xylanase production due to its higher productivity per reactor volume, lower capital investment and lesser energy demand. Hence, various parameters of medium formulation were investigated to obtain the maximum activity of xylanase by A. brasiliensis in SsF. Additionally, to reduce the costs of production, agricultural residuals were used instead of xylan. In this study, the optimisation of carbon source using agricultural residuals combined with nitrogen source was elucidated for the maximum xylanase production by A. brasiliensis in SsF.
Results: From our results, 10 g wheat bran as the optimum agricultural residual was able to produce xylanase activity of 6.7091 U/mL at 48 h of SsF. Subsequently, 6.7115 U/mL of xylanase was obtained using wheat bran as the optimised carbon source at the substrate to moisture content ratio of 1:1. Interestingly, when 2% yeast extract was added, further study reviewed the maximum xylanase activity increased to 28.75%.
Conclusion: In conclusion, the optimum medium formulation for the maximum production of xylanase by A. brasiliensis was achieved using 10 g wheat bran as the optimised carbon source at the substrate to moisture ratio of 1:1 combined with 2% yeast extract as the optimum nitrogen source cultured at optimum temperature of 30°C at 150 rpm up to 48 h of SsF.
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