| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
This study was performed to identify the environmental factors that induce coccoid formation of Helicobacter pylori (Hp), and to clarify their significance in the bacterial life cycles. The results of this study are summarized as follows;
1. We found that an anti-oxidant, sodium bisulfite, induces coccoid formation of exponentially growing Hp cells, which consequently results in cell death. Since coccoid formation can be implicated to be a course of bacterial differentiation, the result suggests that growth-and-differentiation status of Hp is coordinately regulated in response to environmental factors surrounding the bacterial cells.
2. In order to search the environmental factors from natural resources, we established a method with which we can explore and screen the coccoid formation factors (CF) and their activity. Using this system, we found two distinguishable activities in the long-term culture of Hp ; one induces, and the other inhibits the coccoid formation. CF in the bacterial culture showed a molecular weight less than 3,000, is resistant to heating (100℃, 5 min), and sensitive to a reducing agent.
3. We found that NaCl at physiological concentrations in solution significantly inhibits coccoid formation of Hp. This inhibitory activity seemed to be unrelated to osmotic stress by NaCl, because increased osmolarity created by uncharged saccharide did not induce the inhibition. Further experiments using several salts with different combinations of anions and cations suggested that Na^+ could be an inducing agent of the inhibition
4. Amiloride, a inhibitor for Na^+/H^+ antiporter, partially released the inhibition by Na^+, suggesting that Na^+ incorporated in bacterial cells may influence physiological status of Hp, leading to differentiation of Hp to coccoid form.
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