Vol.4 No.4 2012

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Research paper : Efficient production of active form of vitamin D3 by microbial conversion (Y. Yasutake et al.)−235−Synthesiology - English edition Vol.4 No.4 (2012) 4 Significance of high activation of enzyme in the production processComment (Kazunori Nakamura)You describe the increase of the activity of the enzyme itself in achieving high activation. I think you need to provide some description on how effective this activity increase is in the actual production process. I think it will be better if the reader can image how much cost reduction can be ultimately achieved by such a process.Answer (Yoshiaki Yasutake, Tomohiro Tamura)In the laboratory level analysis, high enzyme activation or the increased intracellular accumulation of enzymes were achieved, yet these have not led to the dramatic improvement of the production volume of 25(OH)VD3. This may be because VD3 is a fat-soluble substance, and transfer into and out of the cell is limited greatly compared to water-soluble molecules. The conversion rate was improved significantly by increasing the solubility by trapping the VD3 in cyclodextrin, but the improvement of activity dependent on the accumulation volume of the intracellular enzyme was not confirmed. As described in the paper, we obtained the result that the conversion activity could be increased by removing the barrier of VD3 cell membrane permeability by using the antibacterial substance nisin. However, when the nisin-treated cell was used, the production volume of the hydroxylated VD3 increased according to the accumulation volume of the intracellular enzyme. I predict that similar effect will be obtained if highly active enzymes are used. In the near future, if we could use the system, in which the membrane permeability is improved using nisin, in actual production, I think the highly active enzyme can exert its potential sufficiently.

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