Effects of Medium Components and Fermentation Conditions on Cytidine Production by Recombinant Escherichia coli CYT20
Recently, cytidine is gaining more attention as a precursor for antiviral drugs. Cytidine is produced by some microorganisms fermentation. Cytidine producing strain Escherichia coli CYT20 was bred in our previous study. Glucose, (NH4)2SO4, and temperature
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Effects of Medium Components and Fermentation Conditions on Cytidine Production by Recombinant Escherichia coli CYT20 Haitian Fang, Xixian Xie, Qingyang Xu, Chenglin Zhang and Ning Chen Abstract Recently, cytidine is gaining more attention as a precursor for antiviral drugs. Cytidine is produced by some microorganisms fermentation. Cytidine producing strain Escherichia coli CYT20 was bred in our previous study. Glucose, (NH4)2SO4, and temperature were selected as variables for optimization of fermentation medium and conditions for cytidine production. Among ingredients, different concentrations of initial glucose and (NH4)2SO4 had positive effects on cytidine production, and pH 7.0 and temperature 36 °C were favoured fermentation conditions for cytidine production by E. coli CYT20. After shake flask batch fermentation, production of cytidine was measured by high performance liquid chromatography. The results showed that it was 1,866 mg/l under optimized condition and it was 1,115 mg/l under un-optimized condition, cytidine production was increased by 67.4 %. Keywords Culture conditions Optimization
Cytidine Escherichia coli Fermentation
2.1 Introduction Cytidine is a nucleoside molecule that is formed when cytosine is attached to a ribose or deoxyribose ring. Cytidine is used as a precursor of a number of commonly used antiviral drugs. The production of cytidine depends on direct fermentation of carbohydrates by auxotrophic and regulatory mutant of Escherichia coli and Bacillus H. Fang X. Xie Q. Xu C. Zhang N. Chen (&) College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, People’s Republic China e-mail: [email protected] H. Fang College of Agriculture, Ningxia University, Yinchuan 750021, People’s Republic China
T.-C. Zhang et al. (eds.), Proceedings of the 2012 International Conference on Applied Biotechnology (ICAB 2012), Lecture Notes in Electrical Engineering 249, DOI: 10.1007/978-3-642-37916-1_2, Ó Springer-Verlag Berlin Heidelberg 2014
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subtilis [1, 2]. Among these species, E. coli stains have been developed by mutagenesis or genetic manipulation for its high growth rate and well-known physiological characteristics [3]. A mutant of E. coli CYT20, which was released from the repression and inhibition of two key enzymes by end-products was isolated, and the concentration of glucose as a carbon source and (NH4)2SO4 as a nitrogen source for the production of cytidine by this stain was optimized [4]. It is important to maintain the optimal fermentation conditions throughout the production process, including temperature, pH and carbon source content, and nitrogen source content [5–7]. A variable temperature control strategy is an efficient technique to control the organism’s growth rate and achieves high yields of biomass and metabolites. The above-mentioned approach has been successfully applied in the productions of cytidine. In this study, the effects of the nitrogen source, the initial concentration of carbon source, temperature, and
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