| 研究実績の概要 |
The Microcystis - N111, Pseudanabaena - N512, Ambiguum - N2119 were obtained from NIES, Japan and cultured in incubators with BG11 as the nutrient supply. To multiplying the cultures took around five months. Initial experiments were conducted to understanding the critical values and behaviors of species which can be applied for the control approaches. As for the first experiment we exposed two species (Microcystis, Pseudanabaena) to different light intensities 0, 50, 100, 150 and 200 umol/m2/s photosynthetically active radiation intensity (PAR) and observed the oxidative stress in term of H2O2 content and the antioxidant activity in term of Peroxidase activity (POD). It was revealed that with the increasing light intensity, H2O2 was proportionately increased until 0-50 umol/m2/s light range. The 100 and 200 umol/m2/s showed opposite trends. When the H2O2 to POD correlation concerned it revealed that the relationship is negative for both species. The second experiment was conducted to investigate the diurnal variation of parameters APX, CAT, SOD and OD730. Under the experiment two species (Microcystis, Ambiguum) were exposed to varying light intensity every three hours from 0 - 300 umol/m2/s during 6:00 to 12:00 and 300 - 0 during 12:00 to 18:00. The same method was used for the 600 umol/m2/s. It was revealed that the APX, CAT, and SOD followed an increasing trend with the increasing light intensity and decreased with the decreasing light intensity. However, the values were always high with the higher intensity. The OD730 was not significantly change under the conditions.
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| 今後の研究の推進方策 |
The future studies will be targeted on understanding the Cyanobacteria responses to Temperature and light combined exposure conditions which is common in natural conditions. Three species (Microcystis - N111, Pseudanabaena - N512, Ambiguum - N2119) will be used for the studies. This experiment will be able to determine threshold H2O2 concentration which each species would survive. The temperature will be controlled at 10, 20 and 30 °C with the light intensities 0, 10, 30, 50, 100, 300, 600 umol/m2/s. Further, it is expected to continue research with light intensity and the flow velocity combined. Flow velocity will be kept at 0, 2, 5, 8, 10 cm/s with light intensities within 0 - 600 umol/m2/s range. Further high intensities up to 1000 umol/m2/s range will be applied with different temperature and flow conditions; however, based on the results of the previous experiments, range of temperature and flow velocity will be determined. Data of these experiments will be used to derive emphatical equations which will be abled explain the stress level of light intensities and the velocities on three species. Same time, practically possible stress combinations with light stress which can bring the stress exceeding the threshold H2O2 content will be determined and tested.
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