Optimization of culture conditions for the production of an extracellular ribonuclease by <Emphasis Type="Italic">Aspergillus niger</Emphasis> in a benchtop bioreactor |
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Authors: | Ya-Hong Xiong Jian-Zhong Liu Hai-Yuan Song Liang-Nian Ji |
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Institution: | (1) Biotechnology Research Center and Department of Chemistry, Zhongshan University, 510275 Guangzhou, China |
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Abstract: | SummarySelf-directing optimization was successfully employed to determine the optimal combination of engineering parameters, viz., pH, aeration rate and agitation rate, for extracellular ribonuclease production by Aspergillus niger SA-13-20 in a batch bioreactor. Maximal RNase production of 5.38 IU ml–1 was obtained at controlled pH of 2.33, aeration rate of 1.67 v/v/m and agitation rate of 850 rev/min. The effect of oxygen on the fermentation was also investigated. With increase in volumetric oxygen transfer coefficients (KLa), cell growth and RNase production first increased and then decreased. RNase production was further increased to 7.10 IU ml–1 and the fermentation time was shortened from 96 to 72 h by controlling dissolved oxygen concentration at 10% saturation by aerating oxygen after about 28 h of fermentation under the above optimal condition. The kinetic model showed that RNase production by A. niger SA-13-20 was growth-associated. |
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Keywords: | Aspergillus niger dissolved oxygen ribonuclease self-directing optimization volumetric oxygen transfer coefficient |
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