| Budget Amount *help |
¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 1994: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1993: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1992: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Research Abstract |
In low nutrient level of the seawater, some bacteria devise a survival strategy, namely, the bacteria are able to lyse other bacterial cells and to grow by utilizing organic matters released from lysed cells. The aim of this study was to isolate the bacteria having bacteriolytic activity from coastal area and to elucidate a mode of their bacteriolysis and a role of them in microbial ecology. The following are main results in this study.
1. Many bacterial strains having bacteriolytic activity were isolated from the coastal seawater and seaweeds. Most of them were identified to Alteromonas, Alcaligenes, Vibrio and Cytophaga.
2. During the growth of Alteromonas sp.No.8-R isolated from the culture bed of Laminaria japonica, four bacteriolytic bands (a, b, c and d) were detected in the culture supernatant and the cells at different stage of growth. Bacteriolytic band d was detected in the supernatant from the logarithmic phase to the stationary phase and disappeared at the decreasing phase. B
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and b was maintained in intracellular to the stationary phase and detected in the culture supernatant at the decreasing phase. Band a and c were detected in the culture supernatant in the decreasing phase. Band a and c were detected in the culture supernatant in the decreasing phase.
3. The bacteriolytic enzyme b produced by Alteromonas sp.No.8-R was purified from the culture supernatant. The enzyme was estimated to have a molecular weight of 74kDa. Optimum pH and temeperature of the enzyme were 8.0 and 40^oC,respectively. From the result of this experiment, it is presumed that the enzyme b may be an intracellular enzyme or autolysin.
4. Changes in cell numbers of Alteromonas sp.No.8-R,a non-obligate bacterial predator, and two type of bacterial prey, Moraxlla sp.and Micrococcus sp.were investigated in a mixed incubation prepared with sterilized artificial seawater. A marked decrease was observed in the number of predators, while the number of No.8-R changed with the cell density of prey bacteria.
5. The bacteriolytic substance d was partialy purified from the culture supernatant of Alteromonas sp.No.8-R.The substance d was estimated to have a molecular weight of 2.5-3.0 kDa. The substance was stable to heat and ureae treatment. These result suggested that d is not a bacteriolytic enzyme, but some bacteriolytic substance such as a bacteriocin. Less
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