Fermentation Characteristics of Mortierella alpina in Response to Different Nitrogen Sources
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The fermentation characteristics of Mortierella alpina were investigated in response to various nitrogen sources. Influences on nitrogen source and glucose uptake rate, mycelial morphology of M. alpina, and pH of medium in relation to different nitrogen sources were discussed. Effects of different nitrogen sources on cell growth, fatty acid composition, arachidonic acid (ARA), and total lipid concentration were also evaluated. It revealed that the maximum nitrogen source uptake ratio was obtained when corn steep liquor was used as nitrogen source. When yeast extract was used as the sole nitrogen source, glucose was completely exhausted at the end of fermentation. The maximum dry cell weight obtained from medium with yeast extract as nitrogen source had the highest total lipid concentration. Sodium nitrate was the favorable nitrogen source for ARA accumulation, and the highest ARA percentage in total fatty acids was obtained, 35.9%. Urea was identified as the favorable nitrogen source for ARA production, the highest ARA concentration obtained from urea was 5.8 g/l. Compared with inorganic nitrogen sources, organic nitrogen compounds are favorable for both cell growth and total lipids accumulation.
KeywordsArachidonic acid Mortierella alpina Nitrogen source Fermentation characteristics
This work was financially supported by the Key Program of National Natural Science Foundation of China (No. 20936002), the National Basic Research Program of China (Nos. 2007CB707805 and 2009CB724700), the Fifth of Six Projects Sponsoring Talent Summits of Jiangsu Province (No. 2008-D-63), the College Industrialization Project of Jiangsu Province (No. JH09-30), the Fok Ying Tung Education Foundation (No. 123014), and the Program for New Century Excellent Talents in University from the Ministry of Education of China (No. NCET–09–0157).
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