1991 Fiscal Year Final Research Report Summary
Role of Surface-Active Lipids in Fractal Morphogenesis.
| Project/Area Number |
02808026
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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 |
物質生物化学
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| Research Institution | Niigata University |
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Principal Investigator |
MATSUYAMA Tohey Niigata University School of Medicine Dept. of Bacteriology, Associate Professor, 医学部, 助教授 (00047200)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAGAWA Yoji Niigata University General Education Dept. Associate Professor, 教養部, 助教授 (10018799)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Fractal / Morphogenesis / Surface-active lipids / Bacterial colony / Serratia marcescens / Bacterial lipids |
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| Research Abstract |
Surface-active exolipids produced by Serratia spp. were shown to be active in promotion of fractal colony morphogenesis. Structures of these novel lipids were determined. Serrawettin (form S. marcescens) W2 was a cyclodepsipeptide containing a fatty acid (3-hydroxydecanoic acid) and five amino acids. The peptide was proposed to be D-leucine (N-bonded to the carboylate of the fatty acid)-L-serine-L-threonine-D-phenylalanine-L-isoleucine (bonded to the 3-hydroxyl group). Rubiwettin (from S. rubidaea) R1 was proposed to be a mixture of 3-(3'-hydroxytetradecanoyloxy) decanoate, 3-(3'-hydoxyhexadecenoyloxy) decanoate and minor molecular isomers. The structure of rubiwettin RG1 was proposed to be beta-D-glucopyranosyl 3-(3'-hydroxytetradecanoyloxy) decanoate. As suggested by the diffusion-limited aggregation model (DLA) theoretically, fractal dimensions of bacterial colonies were shown to be 1.7 - 1.8 by the box-counting method. In the fractal colony growth, shielding and repulsion effects were also recognized. Thus, bacterial colony growth in a two-dimensional nutrient concentration field was shown to results in fractal pattern formation through diffusion-limited processes. Surface tension seems to exert profound effect on bacterial translocation on the agar surface. Biosufactant described by us may lighten such burden working at the growing colony periphery. Similar pattern formations were demonstrated by computer simulation of DLA model introducing a surface tension parameter.
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