1990 Fiscal Year Final Research Report Summary
Applications and Production of an Extracelllular Ice-Nucleating Substance by the Ice-Nucleating Bacteria
| Project/Area Number |
01550766
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
発酵工学
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| Research Institution | Kansai University |
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Principal Investigator |
OBATA Hitoshi Kansai University Faculty of Engineering Professor, 工学部 (00067646)
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| Co-Investigator(Kenkyū-buntansha) |
TOKUYAMA Tai Kansai University Faculty of Engineering Professor, 工学部, 教授 (60067519)
HASEGAWA Yoshie Kansai University Faculty of Engineering Lecturer, 工学部, 専任講師 (30156327)
TANISHITA Junichi Kansai University Faculty of Engineering Lecturer, 工学部, 専任講師 (50067584)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Ice-Nucleating bacteria / Erwinia uredovora / Pseudomonas viridiflava / Ice-Nucleating temperature / Extracellular Ice-Nucleating substance / Ice-Nucleating medium / Protease / Protein-Modifying reagent |
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| Research Abstract |
When Erwinia uredovora (KUIN-3) was cultured aerobically in a medium consisting of Simmons-citric acid broth (pH 6.1) for 24 hr at 18 ^ﾟC, the ice-nucleating activity of strain KUIN-3 cells was obtained. The ice-nucleating temperature, T_<50>(^ﾟC) was detected at -2.8 ^ﾟC in cell suspensions (1.1 x 10^8 cells/ml) of KUIN-3.
The production of an extracellular ice-nucleating substance by KUIN-3 was examined. In an ice-nucleating medium containing yeast extract, 30 g ; sucrose, 10 g ; DL-serine, 2 g ; DL-alanine, 2 g ; K_2SO_4, 8.6 g and MgSO_4・7H_2O, 1.4 g, in one liter of distilled water, maximum growth was obtained with 1.1 mg/ml of the extracellular ice-nucleating substance at 18 ^ﾟC after 48 hr of shaking.
Cell-free ice nuclei were shed from Pseudomonas viridiflave (KUIN-2) cells with 2 % Triton X-100 in the presence of 10 mM EDTA-2Na. KUIN-2 shed cell-free ice nuclei (0.22 mg protein/ml) active at -4.9 to -5.8 ^ﾟC. The ice-nucleating activity was greatly decreased by treating the cell-free ice nuclei for 30 min at 40 ^ﾟC, and was completely lost by heating at 90 ^ﾟC. The ice-nucleating activity of the cell-free ice nuclei was inhibited by the addition of proteases, protein-modifying reagents and denaturants. It is suggested that the ice-nucleating activity sites of cell-free ice nuclei contain proteins. The ice-nucleating activity of cell-free ice nuclei containing Mg^<2+> occurred within the temperature range -3.3 to -3.6 ^ﾟC.
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