Studies On The Adaptability Of Three Arctic Microalgae To Temperatures

In order to study the adaptability of three algal species (Skeletonema marinoi, Chlorella sp. and Chlamydomonas sp.),which separated from melted glacial water to different temperatures,the growth curve, antioxidant enzyme system, the composition of fatty acid,ultrastructure and pigment at different temperatures(0℃,4℃,8℃) were examined in detail. The results were listed as follows:1. According to the results of growth curve,it was found that the situation of growth is different at different temperatures. The life cycle of Chlamydomonas sp. is shortest (about 28 d),but the life cycle of Skeletonema marinoi were longest. Skeletonema marinoi had the adaptability of low temperature clearly,but the lower temperature can restrain the velocity of growth. Chlorella sp. are easy to adapt the relative higher temperature,and Chlamydomonas sp. had adaptability in large range of temperature, there has no prominent difference at different temperatures.2. In the life curve of Skeletonema marinoi,the difference between 0℃and 4℃of antioxidant enzyme system and the content of MDA was very prominent(p < 0.01)and the difference between 0℃and 8℃of CAT activity of Skeletonema marinoi and Chlorella sp was prominent too(p < 0.05);the difference of antioxidant enzyme system and the content of MDA of 3 algal species were not prominent,in their life cycles,based on its own special metabolizable mechanisms,they could make a balance within their cell under antioxidant enzyme system at different temperatures, and keep their body in a normal metabolizability and growth system,so they have well adaptability at different temperatures.3. The three microalgae presents mainly in the form of polyunsaturated fatty acid, which play a crucial role in keeping the fluidity of membrane for adapting the different environment. The content of C20:4 in Skeletonema marinoi is highest under the most adaptable temperature. C18:3 in two green algae has the highest percentage,and the variation of temperature has some influence in the content of fatty acid. Reducing or increasing temperature are in favor of the accumulation of polyunsaturated fatty acid, the variety of fatty acid is differentto different species.4. According to the ultrastructure of two chlorophyta,two chlorophyta experience low temperature environment in the form of storing fat;Skeletonema marinoi and Chlorella sp. keep their normal life depending on expanding the cell volume. In general,the change of ultrastructure was minor at three temperatures,which denotes that the adaptability of microalgae was ideal in this experiment.5. According to the results of spectral scanning, the pigment of three species microalgae was in line with their growth curve. The concentration of Chla, Chla/cell, Chlc/Chla, Chlb/Chla, Car/Chla,and the contribution of PSI and PSII to Chla, were different according to different culturing temperatures and species of algae, which denoted that the photosynthetic system of different algae presented different response to the change of temperature.In a word,the author discussed the adaptability of three species microalgae to different temperatures from the angle of physiological and biochemical changes,ultrastructure and fatty acids,the results mentioned above showed that the three algal species have well adaptability through its own metabolizability,and they can maintain normal metabolizability and growth which in our studies.