| There are rich polysaccharides, proteins, lipids and other high-value bioactive substances in marine microalgae cell, it plays an important role in the national economy and people’s living. Studies have shown that polysaccharides and proteins in marine microalgae have the effects of anti-tumor, anti-viral, anti-oxidation, and strengthening the immune system and so on; lipid in microalgae has high value on nutrition and medicine for whether animals or humans. Marine microalgae is an important source of high-value chemicals and pharmaceuticals. Microalgae has considerable lipid and fatty-acid and microalgae generally has 14 to 20 carbon chains, is similar the number of the carbon chain of about 14 to 18 in biodiesel, so lipid extracted from microalgae has a wide range of application, it can be directly used as biological applied to industrial diesel.The conditions and environmental characteristics decide bioactive substance in microalgae has a unique chemical structure and function compares to terrestrial plants. More and more studies show that temperature as an important ecological factors affects the growth and reproduction of marine microalgae, a variety of biochemical reactions in microalgae cells, the regulation of enzyme activity are all directly related to temperature. Each microalgae has a optimum temperature range,in this range growth reproduction and the cell metabolism are exuberant. Typically,in the optimum temperature range, heating can accelerate the growth of algae and cooling can reduced the growth of algae, the temperature is too high or too low will have an impact on physical activities, even a threat to the survival of microalgae.In this paper, Fourier transform infrared spectroscopy and GC-MS spectrometry was used to analysis different temperatures on the growth and intracellular polysaccharide, protein and lipid content and structure in three species of marine microalgae(Phaeodactylum tricornutum, Chlorella vulgaris, Nannochloropsis sp.)and a freshwater microalgae(Scenedesmus quadricauda). Aim to provide evidence for the development and utilization of marine microalgae. The main findings are as follows:1. The optimum growth temperature for the Phaeodactylum tricornutum,Nannochloropsis sp.and Scenedesmus quadricauda is 25 oC, for Chlorella vulgaris is20 oC.2. Fourier transform infrared spectroscopy measured that the effect of temperature on relative content of four microalgae is: for Phaeodactylum tricornutum, 25 o C is most conducive to the accumulation of polysaccharide, 15 oC is to protein, 25 oC is of lipid; for Chlorella vulgaris, 15 o C is most conducive to the accumulation of polysaccharides, 20 oC is to protein, 25 oC is to lipid; for Nannochloropsis sp., 25 oC is most conducive to the accumulation of polysaccharides, 15 oC is to protein, 25 oC is to lipid; for Scenedesmus quadricauda,15 oC is most conducive to the accumulation of polysaccharides, 20 oC is to protein,15 oC is to lipid.3. Fourier transform infrared spectroscopy measured that the effect of temperature on structure of four microalgaes is: for Phaeodactylum tricornutum, 25 oC has the most carbohydrates C-O-C structure, the most protein content is in 20 oC and culturing in this temperature is no missing group, the species of polysaccharides,proteins and lipids are the most abundant; for Chlorella vulgaris and Nannochloropsis sp., 25 o C is most conducive to generating C-O-C structure of carbohydrates and C=O structure of lipids, 20 oC is for generating protein and culturing in this temperature is no missing group for this two microalgaes, the species of polysaccharides, proteins and lipids are the most abundant; As the only freshwater algae, Scenedesmus quadricauda will be missing some group of biological macromolecules in the three temperatures, so Scenedesmus quadricaudais not a good algal source for providing polysaccharide and protein.4. GC-MS spectrometry measured that the effect of temperature on content and composition of four microalgaes is: for Phaeodactylum tricornutum, 15 oC is most benefit to accumulate monounsaturated fatty-acids(MUFA) and polyunsaturated fatty-acids(PUFA)(including EPA and DHA), while 25 oC has the most content of saturated fatty-acids(SFA) and C14-C18 that can be prepared as biodiesel; for Chlorella vulgaris, the accumulation of saturated fatty-acids(SFA) is the most in the temperature of 15 oC, 20 oC is the most benefit to accumulate monounsaturated fatty-acids(MUFA)and the two kinds of polyunsaturated fatty-acid EPA and DHA,25 oC is most conducive to accumulation of C14-C18; for Nannochloropsis sp., 25 oC is most conducive to accumulation of saturated fatty acids(SFA),monounsaturated fatty acid accumulation(MUFA) and polyunsaturated fatty acids(PUFA), and the content is increasing with the temperature’s rise, at the same time,the content of EPA and C14-C18 also increased; Scenedesmus quadricauda has the most content of saturated fatty acid(SFA), polyunsaturated fatty acids(PUFA) and C14-C18 that was suitable for the preparation of biodiesel under high temperature at each culture period. |
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