| Project/Area Number |
12680628
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional biochemistry
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| Research Institution | NIIGATA UNIVERSITY |
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Principal Investigator |
MATSUYAMA Tohey NIIGATA UNIVERSITY Graduate School of Medical and Dental Sciences, Associate Professor, 大学院・医歯学総合研究科, 助教授 (00047200)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUSHITA Mitsugu Chuo University Faculty of Science and Engineering, Professor, 理工学部, 教授 (20091746)
NAKAGAWA Yoji Faculty of Agriculture Professor, 農学部, 教授 (10018799)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2001: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2000: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | bacteria / biofilms / drug resistance / Serratia marcescens / bacterial population system / cell membrane lipids / membrane filter / Pseudomonas aeruginosa / バイフィルム / 細菌集団行動 / 表面 / Bacillus subtilis / Proteus mirabilis / 集団構造 |
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| Research Abstract |
1. Drug resistance of bacterial biofims (Bf) has been considered to be due to extracellular polysaccharide (EPS) which may hinder diffusion of drugs. In searching for other reasons of drug resistance, we isolated Serratia marcescens mutants which are able to construct thick Bf, but the formed Bf are defective in developing drug resistane. Since planktonic cells of these mutants showed normal drug susceptibility, these mutants seemed to be defective in Bf specific resistance mechanisms. Sequencing and homology analyses with three identified genes indicated that functions related to biosynthesis of LPS and EPS, and siderophore uptake may be involved in drug resistance at the population level of Bf.
2. In Bf, local micro-conditions such as pH, concentration of nutrients or O_2 are heterogeneous. Consequently, bacteria composing Bf are heterogenous. So, if some bacteria are in drug resistant status, it will be difficult to eradicate Bf. We found that Pseudomonas aeruginosa and some other ba
… More
cterial species change their cellular membrane from phospholipid-rich to ornithinelipid-rich composition under phosphorus-poor condition. Such drastic changes in bacterial membranes may induce susceptibility changes to chemicals and physicochemical factors. So, bacteria growing under phosphorus-poor condition was examined for susceptibility. There were no remarkable resistance increase to antibacterial drugs, but bacteria having ornithinelipid-rich membrane showed strong acid resistance.
3. Planktonic bacteria coexisting with Bf demonstrated increased drug resistance. Unknown substances released from Bf seemed to contribute to the increased drug resistance. Effects of membrane permeable substances from Bf were examined with planktonic bacteria in the chamber facing the MF membrane which carried Bf of P. aeruginosa on the another face. The planktonic bacteria certainly showed increased drug resistance. In addition, in the chamber separated by MF membrane we found bacteria which should be contained in the chamber with Bf. A novel bacterial activity, "membrane filter (pore size, 0.22 mm) passing-through activity" was discovered. Less
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