Improvement of production of l-aspartic acid using immobilized microbial cells |
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Authors: | Isao Umemura Satoru Takamatsu Tadashi Sato Tetsuya Tosa Ichiro Chibata |
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Affiliation: | (1) Research Laboratory for Applied Biochemistry, Tanabe Seiyaku Co., Ltd., 16-89, Kashima-3-chome, Yodogawa-ku, Osaka, Japan;(2) Research and Development Headquaters, Tanabe Seiyaku Co., Ltd., 16-89, Kashima-3-chome, Yodogawa-ku, Osaka, Japan |
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Abstract: | Summary In our laboratory, EAPc-7 a strain having higher aspartase activity was derived from Escherichia coli ATCC 11303. For the improvement of l-aspartic acid productivity using EAPc-7 cells immobilized in -carrageenan, it was necessary to eliminate the fumarase activity which converts fumaric acid to l-malic acid. Several treatments for specifically eliminating fumarase activity from EAPc-7 cells were tested and it was found that when EAPc-7 cells were treated in a culture broth (pH 4.9) containing 50 mM l-aspartic acid at 45° C for 1 h, fumarase activity was almost completely eliminated without inactivation of the aspartase.The treated cells, immobilized in -carrageenan, were used for continuous production of l-aspartic acid from ammonium fumarate. The formation of l-malic acid was negligible and the half-life of the immobilized preparation was 126 days.Productivity of immobilized preparation of treated EAPc-7 cells in l-aspartic acid production was six times of that of the parent cell preparation. |
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