Utilization of Corn Cob Waste for Cellulase-Free Xylanase Production by Aspergillus niger DX-23: Medium Optimization and Strain Improvement

详细信息    查看全文

• 作者：Dhara I. Desai ; Bragadish D. Iyer
• 关键词：Xylanase ; Aspergillus niger DX ; 23 ; Corn cob waste ; Optimization ; Strain improvement ; Response surface methodology
• 刊名：Waste and Biomass Valorization
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：8
• 期：1
• 页码：103-113
• 全文大小：
• 刊物类别：Engineering
• 刊物主题：Engineering, general; Environment, general; Renewable and Green Energy; Industrial Pollution Prevention; Waste Management/Waste Technology; Environmental Engineering/Biotechnology;
• 出版者：Springer Netherlands
• ISSN：1877-265X
• 卷排序：8

文摘

Aspergillus niger DX-23 produces a cellulase-free xylanase which showed efficient deinking of old newspaper pulp for recycled paper production. Towards economical production of the above xylanase when various agro-waste biomass were evaluated as substrates, under shake flask conditions, A. niger DX-23 produced highest amount of xylanase (59.5 ± 5.0 U/mL) using corn cob powder as substrate. A central composite design was used to optimize concentration of corn cob powder, NaNO₃ and KH₂PO₄ in the medium for maximum xylanase production. The optimum concentration of the above nutrients were determined to be 37.0 g/L corn cob powder, 2.5 g/L of NaNO₃ and 1.0 g/L of KH₂PO₄ at which level xylanase yield of 110.4 U/mL was obtained, which was 82.9 % more than the yield obtained in unoptimized medium. Moreover, under shake flask conditions, 5.0 % (v/v) of inoculum, pH of 5.0 and incubation time of 84 h was found to be suitable for maximum xylanase production. At laboratory fermentor level, A. niger DX-23 produced 79.4 U/mL (after 96 h) and 117.9 U/mL (after 72 h) xylanase using untreated corncob powder and alkali treated corn cob powder, respectively. In order to obtain higher xylanase procuring strains, A. niger DX-23 was mutagenized using UV rays. In optimized medium mutant strain of A. niger produced 150.9 ± 3.4 U/mL of xylanase which was 118.0 % higher than the xylanase yield obtained for parent type in unoptimized medium (60.2 ± 2.6 U/mL). The above results suggested effectiveness of the combined strategy of medium optimization and mutation towards enhanced production of xylanase by A. niger.