Research On Accumulation Of Lipid And The Factors Affecting The Lipid Content Of Chlamydomonas Reinhardtii

In recent years, due to the quick depletion of fossil fuels and production of greenhouse gas carbon dioxide from their combustion, human society is in urgent need to develop cleaner, renewable alternative energy. Microalgae, higher oil content and higher growth rates, are considered to be potential sources for biodiesel production. Lipid content and composition of microalgae could be modified by cultural condition optimization and genetic engineering. To explore some metabolic controlled factors relevant to lipids accumulation, the effects of nitrogen deficiency, magnesium deficiency and downregulating enoyl coenzyme A hydratase gene on growth and lipids accumulation in Chlamydomonas reinhardtii cc503 was investigated.(1) When cells re-inoculated into magnesium depleted TAP media, growth decreased and neutral lipid accumulation determined with spectrofluorimetry increased significantly, total lipid content increased by 16.38%, while chlorophyll, total sugar and the total protein changed significantly. Magnesium deficiency affected not only the synthesis of proteins and chlorophyll but also important protein and enzymes invoved in photosynthesis were influenced.(2) When cells re-inoculated into nitrogen depleted TAP media, the total lipid content and neutral lipid content increased significantly. Chlamydomonas reinhardtii cells probably contain 41.96% saturated fatty acids and 58.04% unsaturated fatty acids in response to nitrogen deficiency while the saturated fatty acids and unsaturated fatty acids content under normal culture conditions was 34.26% and 65.74%. Protein synthesis was restrained by nitrogen deficiency, and metabolic flew to lipid anabolism without nitrogen.(3) Enoyl-coenzyme A hydratase is a key enzyme in fatty acid β oxidation. ECH gene was downregulated by RNA interference. The neutral lipid content of the transgenic algae cells was significantly increased, total lipid increased by 13.91%-17.20%.while the transgenic algae cells contain about 42.92% saturated fatty acids and 57.09% unsaturated fatty acids.