研究者詳細 - 倉田　博之

論文 - 倉田　博之

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Software of living systems 査読有り

Ohtake H., Tsuji T., Kurata H.

Kagaku Kogaku Ronbunshu 25 ( 2 ) 174 - 176 1999年03月

担当区分：責任著者掲載種別：研究論文（学術雑誌）

To understand the elaborate system of a living organism, it is essential to know its "software", as well as its "hardware". The software of a living organism may be defined as the package of algorithms (methods and procedures) for its survival. The hardware of a living organism is encoded by genes on the chromosome. Its behaviors should be explainable on the basis of algorithms. The algorithms of a living system can be viewed as biological information that has been envolved over its long history of evolution. Among living organisms are bacteria that are probably the simplest systems for analyzing the software of living organisms. In the present paper, we describe our method for constructing a virtual bacterial system as a tool for analyzing the software of a living organism. We also describe bacterial algorithms for surviving during phosphate starvation and exhibiting an intelligent behavior called chemotaxis. In addition, we demonstrate a mobile robot whose behavior is controlled by a computer program designed on the basis of the bacterial chemotaxis algorithm.

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Intermittent light irradiation with a second-scale interval enhances caffeine production by Coffea arabica cells 査読有り

Kurata H., Achioku T., Okuda N., Furusaki S.

Biotechnology Progress 14 ( 5 ) 797 - 799 1998年09月

担当区分：責任著者掲載種別：研究論文（学術雑誌）

We developed novel equipment that intermittently illuminates Coffea arabica cell suspensions at a second-scale interval and investigated how intermittent irradiation enhances caffeine biosynthesis by C. arabica cells. The light/dark cycles consisting of 2 s of illumination and 18 s of darkness enhanced caffeine production, reaching the same level as for continuous light. The intermittent illumination increased the production efficiency regarding light consumption by a factor of 10. Caffeine production was determined by light intensity regardless of intermittent or continuous light irradiation. We propose a new concept for designing a photobioreactor that is applicable to secondary metabolite production by plant cell culture.

DOI： 10.1021/bp980065u

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Light enhanced target gene expression in tobacco BY-2 by the combination of overexpressed phytochrome and rbcS3A promoter 査読有り

Kurata H., Furusaki S., Kado C.

Biotechnology Letters 20 ( 5 ) 463 - 468 1998年07月

担当区分：責任著者掲載種別：研究論文（学術雑誌）

Enhanced expression of the rbcS3A promoter was achieved by overproducing phytochrome in BY-2 tobacco cells. The transformed cells contained the oat phytochrome A gene fused the 35S promoter of Cauliflower Mosaic Virus (CaMV) and the gus gene to the rbcS3A promoter. The transformed cells exhibited 1.5- to -2.8 fold enhanced the β-glucuronidase (GUS) activity when subjected to light.

DOI： 10.1023/A:1005484011673

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The light/dark cycle operation with an hour-scale period enhances caffeine production by Coffea arabica cells 査読有り

Kurata H., Achioku T., Furusaki S.

Enzyme and Microbial Technology 23 ( 7-8 ) 518 - 523 1998年01月

担当区分：責任著者掲載種別：研究論文（学術雑誌）

The intermittent light irradiation with an hour-scale period is used for producing caffeine by Coffea arabica cells. Three factors concerning the light/dark cycle operation such as light intensity, the length of the cycle (period), and the ratio of the illumination time to the dark time (light/dark ratio) were investigated to optimize the caffeine production efficiency regarding light consumption. The light/dark ratio of 1/1 enhanced caffeine production, reaching the same level as continuous light; thus, the intermittent light irradiation improved the production efficiency twofold. The production was not influenced by the period, but was determined by light intensity regardless of intermittent or continuous light irradiation. Copyright (C) 1998 Elsevier Science Inc.

DOI： 10.1016/S0141-0229(98)00081-7

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Light-controlled expression of a foreign gene using the chalcone synthase promoter in tobacco BY-2 cells 査読有り

Kurata H., Takemura T., Furusaki S., Kado C.

Journal of Fermentation and Bioengineering 86 ( 3 ) 317 - 323 1998年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The light-activated chalcone synthase (CHS) gene promoter was used to control the expression of a foreign gene - the uidA gene, whose product is β-glucuronidase (GUS) - in tobacco BY-2 cell suspensions. Light enhanced GUS specific activity rapidly and greatly in transgenic BY-2 containing a fusion of the CHS promoter and uidA gene. GUS production was turned on/off by using a light/dark cycle. The level of promoter activity was almost proportional to the intensity of light, surpassing the strength of the 35S promoter of Cauliflower Mosaic Virus (CaMV). Intermittent illumination induced the same level of GUS production as continuous light. The CHS promoter is thus useful for producing a foreign protein in plant cell bioreactors.

DOI： 10.1016/S0922-338X(98)80137-2

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Light irradiation causes physiological and metabolic changes for purine alkaloid production by a Coffea arabica cell suspension culture 査読有り

Kurata H., Matsumura S., Furusaki S.

Plant Science 123 ( 1-2 ) 197 - 203 1997年03月

担当区分：責任著者掲載種別：研究論文（学術雑誌）

Light irradiation not only enhanced purine alkaloid (caffeine and theobromine) production by a Coffea arabica cell suspension culture, but also caused physiological changes in cell growth, and sugar and oxygen uptake rates. Both sugar and oxygen uptake rates showed maxima between 7 and 10 W/m 2 of light intensity, where the specific production rate reached the highest, although the specific cell growth rate was reduced by more than 50%. Light acts as a stress for enhanced production. The activities of enzymes related to purine alkaloid production were induced by light after a lag-time of 1 day. Light is an inducer for these enzymes. However, the de novo synthesis of purine alkaloids required at least 6 days of light irradiation. This discrepancy was caused by the insufficient supply of purine rings, the precursors for biosynthesis of purine alkaloids.

DOI： 10.1016/S0168-9452(96)04588-8

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Increased alkaloid production in a suspension culture of Coffea arabica cells using an adsorption column for product removal 査読有り

Kurata H., Kawai A., Seki M., Furusaki S.

Journal of Fermentation and Bioengineering 78 ( 1 ) 117 - 119 1994年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Since caffeine suppresses purine alkaloid (caffeine and theobromine) production by Coffea arabica cells, the effect of removing caffeine from the medium was investigated using the hydrophobic resin Amberlite XAD-4. An in situ removal method did not result in increased production because the adsorbent removed not only the products, but also essential components (hormones). Therefore, the use of an adsorption column employing the hydrophobic resin was investigated with a 35-d semicontinuous culture under light irradiation. Caffeine was removed within 30 min by the adsorption column on day 23 of the cultivation. In this system, the negative effects of hormone removal by the adsorbent were canceled out by the addition of fresh medium. This method increased alkaloid production 1.4-fold compared to the culture with no removal treatment. © 1994.

DOI： 10.1016/0922-338X(94)90192-9

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Immobilized Coffea arabica cell culture using a bubble‐column reactor with controlled light intensity 査読有り

Kurata H., Furusaki S.

Biotechnology and Bioengineering 42 ( 4 ) 494 - 502 1993年08月

担当区分：責任著者掲載種別：研究論文（学術雑誌）

Coffea arabica cells immobilized by calcium alginate gel were photocultured using a bubble‐column reactor under controlled light intensity. This process was carried out after their alkaloid productivity was improved by increasing the cell density in the initial gel matrix and preculturing the immobilized cells in the dark prior to light irradiation. The cells were grown in the form of a biofilm on gel beads, producing 100 mg/L of purine alkaloids in a 24‐day batch culture. Alkaloid production was relatively constant with respect to light intensity changes, and also cell growth was not suppressed much at high light intensity, with these behaviors being different from those obtained using suspended cells. These phenomena are explained by estimating the light intensity gradient within the cell‐immobilizing particles and by measuring the viable cell distribution within them. It subsequently suggests that the subsurface cells affect both the production and growth behaviors. © 1993 John Wiley & Sons, Inc. Copyright © 1993 John Wiley & Sons, Inc.

DOI： 10.1002/bit.260420413

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Nonisotropic Scattering Model for Estimation of Light Absorption Rates in a Suspension Culture of Coffea arabica Cells 査読有り

Kurata H., Furusaki S.

Biotechnology Progress 9 ( 1 ) 86 - 92 1993年01月

担当区分：責任著者掲載種別：研究論文（学術雑誌）

A nonisotropic scattering model is proposed to estimate the light absorption rates in a heterogeneous photoreactor containing plant cells of Coffea arabica and is compared with an isotropic scattering model. In order to determine the directions of noniso‐tropically scattered light, optical theorems (geometrical optics and wave optics) are applied to light scattering caused by a homogeneous and perfect sphere. Two parameters, relative refractive index and attenuation coefficient, are used to characterize the ideal sphere. The primary feature of this model is that various phenomena of light scattering and absorption can be simulated by the combination of the two parameters. A measuring system composed of parallel plates was developed for evaluating the model. The nonisotropic scattering model was successfully applied to the heterogeneous reactor with the cultured plant cells. Copyright © 1993 American Institute of Chemical Engineers (AIChE)

DOI： 10.1021/bp00019a600

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Influence of light irradiation rates and irradiation modes on caffeine production and cell growth in suspension culture of coffea arabica cells 査読有り

Kurata H., Seki M., Furusaki S., Furuya T.

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 24 ( 6 ) 783 - 788 1991年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The effect of light on caffeine production by Coffea arabica cells was investigated using chemical actinometry for the purpose of industrial application of plant cell cultures. Caffeine production by the Coffea arabica cells was greatly increased by light. About a six-day irradiation period was required to increase the caffeine production in a batch culture. Caffeine production significantly increased at a low light irradiation rate of 0.11 J/L/s. Meanwhile, cell growth was suppressed by increasing the irradiation rate. Maximum production was achieved at a moderate irradiation rate of 0.70 J/L/s in a 20-day batch culture. It was shown there was a light irradiation rate that optimized production. Since long-term continuous light greatly suppressed cell growth, the culture was divided into two stages: the production period in the light and the growth period in the dark. The high production and good growth were maintained for 65 days. © 1991, The Society of Chemical Engineers, Japan. All rights reserved.

DOI： 10.1252/jcej.24.783

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Effect of Light on Caffeine Production by Plant Cells of Coffea arabica<sup>a</sup> 査読有り

KURATA H., SEKI M., FURUSAKI S., FURUYA T.

Annals of the New York Academy of Sciences 613 ( 1 ) 538 - 541 1990年12月

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