Effect of amplification of desensitized purF and prs on inosine accumulation in Escherichia coli |
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Authors: | Shimaoka Megumi Takenaka Yasuhiro Kurahashi Osamu Kawasaki Hisashi Matsui Hiroshi |
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Affiliation: | Fermentation and Biotechnology Laboratories, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa 210-8681, Japan. |
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Abstract: | The effect of a phosphoribosylpyrophosphate (PRPP) synthetase gene (prs) that was desensitized to feedback inhibition by ADP on inosine accumulation was investigated using an inosine-producing mutant of Escherichia coli. At the same time, various types of plasmid having a PRPP amidotransferase gene (purF) that was desensitized to feedback inhibition by AMP and GMP were also investigated to improve inosine productivity using a compatible plasmid containing prs with a plasmid containing purF. The recombinant E. coli I-9 harboring a low-copy-number plasmid having the desensitized-purF (pMWKQ) accumulated 3.6 g/l inosine from 40 g/l glucose in a 2-d culture. Furthermore, desensitized-prs amplification, in addition to purF, resulted in the accumulation of 6.2 g/l inosine. Additionally, through these experiments, a spontaneous mutant with an enhanced inosine-producing ability compared with the parent strain I-9 was obtained. The spontaneous mutant I-9m harboring only pMWKQ and I-9m harboring both pMWKQ and pSTVDA (a plasmid having the desensitized-prs) accumulated 6.7 g/l and 7.5 g/l inosine, respectively, from 40 g/l glucose in a 3-d culture. |
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