Optimization Of Culture Conditions Of N.sitophila On Manganese Peroxidase Production, Purification And Characterization Of The Enzyme

Neurospora sitophila belongs to Sordariaceae of ascomycotina, has considerable ability to degrade lignin. Although it is true that mechanisms for Neurospora sitophila to degrade lignin had been studied into details by previous research and what's more, the ligninolytic enzyme produced by Neurospora sitophila had been purified and characterized, while manganese of Neurospora sitophila had not been concerned much so far.In this paper, activities of three main ligninolytic enzymes produce by Neurospora sitophila was investigated, thus their producing curve was obtained, which revealed that among the three enzymes, activity of lignin peroxidase was the highest with 6.45 U/ml on the 6th day of culture; and that of manganese was the second with 0.4 U/ml on the third day of culture, while activity of laccase was feeble. Then with the purpose of getting the manganese interested, culture conditions of Neurospora sitophila had been optimized. Conditions considerd included: ratio and variety of carbon source and nitrogen source, initial pH and manganese concentration of culture media etc. Orthogonal experiment had been employed to invest influences of carbon source, nitrogen source and manganese concentration on enzyme producing. Results suggested that: (1)low carbon and high nitrogen improved lignin peroxidase production, and that manganese addition had no significant effect on peroxidase production but increased other phenylic peroxidase production. All those results were not the same as those reported previously. (2)NeurosporasitopHila growed best in the media composed of 2g/L lignocellulose, 0.5g/L glucose, 1g/L ammonium tartrate and 1g/L yeast extract with pH of 6.0 and sufficient oxygen supply. Activity of manganese reached to 0.8U/L with two fold increasement under those culture conditions.We also do some research on the enzymatic characterization of MnP3. The conclusion as following: 60℃ is the optimum reactive temperature;5.0 is the optimum reactive pH;when Mn²⁺ concentration is 2mM,get the fast reactive rate; Cu²⁺,Fe²⁺,Fe³⁺ promote the reactive rate of the enzyme,but Zn²⁺,Ba²⁺,Mg²⁺ restrain the reaction;the stability of the enzyme is not good, so this restrict its usage .