| Co-Investigator(Kenkyū-buntansha) |
ICHIKAWA Sosaku University of Tsukuba, Institute of Applied Biochemistry, Assistant Professor, 応用生物化学系, 講師 (00292516)
SATO Seigo University of Tsukuba, Institute of Applied Biochemistry, Professor, 応用生物化学系, 教授 (10205924)
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| Research Abstract |
Chitosan oligosaccharides, especially penta-and hexa-oligosaccharides, have attracted much attention because they exhibit many physiological activities such as antibacterial, antitumor, and immunoenhance activities. However, the efficient method to produce them has not been developed because these oligosaccharides are the intermediates of chitosan hydrolysis and stricter control of the hydrolysis reaction must be achieved. In this study, in order to develop the bioreactor for production of chitosan oligosaccharides, the chitosan hydrolysis using immobilized chitosanases was investigated, with regard to the yield of the intermediate target products, pentamer and hexamer of chitosan oligosaccharides. At first, highly stable chitosanase immobilized on an agar gel support was prepared by the multipoint attachment method. Using this immobilized chitosanase, the effects of the operation conditions on the yield of pentamer and hexamer were studied in batch experiments. In the batch hydrolysis
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of chitosan, the composition of oligosaccharides produced was changed by changing of the reaction conditions such as enzyme density of support surface, support particle size, reaction temperature, agitator speed, and initial substrate concentrations. It was believed that these factors all related to the reaction rate and mass transfer rate at the surface of the support materials immobilizing the enzymes. These effects were summarized as a correlation with Damkohler_number (Da) defined as the ratio of the maximum reaction rate to the maximum mass transfer rate, and a clear relationship between the yield of the target intermediates and Da was obtained. In the continuous reaction, the effects of the operation conditions on the yield of the target intermediates were also correlated with Da. From these results, the optimum condition for continuous production of pentamer and hexamer was determined. Under this condition, the continuous production of these oligosaccharides was carried out for a month with a yield of over 37%. Less
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