| Project/Area Number |
63860016
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
製造化学・食品
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| Research Institution | The University of Tokyo |
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Principal Investigator |
ARAI Soichi The University of Tokyo, Dept. of Agric. Chem., Associate Professor, 農学部, 助教授 (20011934)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Michiko The Univ. of Tokyo, Dept. of Agric. Chem., Lecturer, 農学部, 助手 (90107409)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥7,200,000 (Direct Cost: ¥7,200,000)
Fiscal Year 1989: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1988: ¥4,900,000 (Direct Cost: ¥4,900,000)
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| Keywords | Ice nucleation bacterium / Ice nucleation gene / Ice nucleation protein / Freeze concentration / Egg white / Orange juice / 氷核活性細菌 |
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| Research Abstract |
Erwinia ananas, one of the manor ice nucleation-active bacteria living in Japan, was used as material. We first prepared an outer membrane fraction from the material and entrapped it in a calcium alginate gel to produce an ice nucleating agent which can be applied to freeze concentration of fresh foodstuffs such as raw egg white sol and squashed orange juice. It followed that the use of this agent facilitated the concentration of these foodstuffs with no appreciable loss and deterioration of their constituents. The concentration of labile biological tissues and constituents can be similarly carried out by the use of the technique developed here. Our study is directed toward applying it on an enlarged scale.
On the other hand, we also carried out a study of using a purified ice nucleation protein as a possible constituent of the outer membrane. According to the principal amino acid motif, AGYGSTLT, encoded by the known ice nucleation gene of Psudomonas syringas, we synthesized a corresponding oligonucleotide as a probe to screen a positive clone from an E. ananas gene library. The clone was comprised of 5159 base pairs, encoding a protein constituted with 1322 amino acids. It was then subcloned into E. coli YA28 for transformation to an ice nucleation bacterium. The transformant produced an expected ice nucleation protein, 130 Kd, on the form of inclusion body. This protein, even at a concentration of 0.1 mug in 1 ml of bulk water, was able to freeze the water with no great degree of supercooling. It would be possible to entrap the protein in calcium alginate gel prior to being used, in order to minimize its loss and also to warrant its reuse. Our study is progressing to applying this technique to freeze concentration of foods and other important biomaterials.
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