Team:FAFU-CHINA/Description
1.Inspiration
I grew up in Zhongyuan Oilfield, and many people in my family worked in the oil industry. As for me, the scenery of childhood is the crude oil atmospheric distillation column which spewing out flames and the rotating oil pumping machine beside the road. There are several oil-related institutes around my high school, such as geology institute, oil recovery institute and so on. It used to be very busy and there were many small restaurants with special features. But gradually, the oil reserves declined and production costs rose ($120, compared with about $36 in the U.S). People went to work in other oil fields, and the areas they lived in gradually became deserted, which struck me. I wonder if it is possible to replace conventional fossil fuels with an energy source that will not run out? In our team's brainstorm this year, someone mentioned the IEA's report on current energy information, as the increasing of the energy demand, fossil fuels have been facing a depletion, the development of a new renewable energy is immient，so the topic of microalgae biodiesel production was put forward. This is exactly in line with my idea, so we kept filling in and modifying the subject content, and finally became what it is now.
——Haiyong Shu
2.Background
Energy is an important pillar for the survival and development of human society. According to the prediction of IEA[1], the energy consumption system mainly based on fossil energy will not change in the next 20 years. But people have realized that non-renewable energy is flawed. Among the world's proven reserves, the recoverable years of coal, oil and natural gas are 110, 52.5 and 54.1 respectively. With the deepening of mining, it is more and more difficult to extract fossil energy with higher and higher costs, and the quality of products obtained is also gradually reduced. Taking coal as an example, among the world's proven reserves, about 45.2% are anthracite with good quality, and the remaining 54.8% are bituminous coal and lignite with relatively poor quality [2]. Oil is the blood of industry. The imbalance of energy leads to the shift of the world's energy demand to the direction other than oil. The world's energy structure is gradually changing from oil to multi-energy structure.
The extensive use of fossil fuels poses a threat to the living environment of human beings. Inorganic pollutants produced by fossil fuels mainly include CO, CO2, SO2, H2S, COS, CS2, trace metal elements and radioactive particles. According to statistics, human beings release more than 600 million tons of pollutants into the atmosphere every year, among which the content of toxic organic pollutants exceeds 30 million tons [3]. These pollutants generated by the burning of fossil fuels have caused the greenhouse effect, acid rain, ozone layer destruction, haze and other environmental problems. Moreover, the extraction, processing and transportation of fossil fuels have also damaged the ecological environment.
3.Microalgae Biodiesel
Biodiesel has many advantages. Compared with petrochemical diesel, biodiesel releases significantly less carbon monoxide, particulate matter and hydrocarbons after combustion, and is recyclable. In addition, biodiesel has better fuel performance, lubrication performance and safety performance. Therefore, biodiesel is an ideal alternative to fossil fuels[4].
Compared with other sources of biodiesel biomass, microalgae have high photosynthetic efficiency, short growth cycle, high biomass yield, high lipid content and small cultivated land area. Moreover, the microalgal oil extracted from microalgae is generally composed of saturated and unsaturated fatty acids rich in 12-22 carbon atoms, which is suitable for conversion into biodiesel[5,6].
4.Chlamydomonas reinhardtii
We use Chlamydomonas reinhardtii as the chassis organism and build a general platform in it to produce biodiesel. We search for several enzymes and transcription factors in the metabolic pathway of algae, which can increase the oil content and biomass. We construct the corresponding vectors and use electroporation technology to improve the expression of the corresponding genes. After screening, we selected IDH to increase the biomass and lipid content of algae.
We build a light-controlled system to promote the expression of downstream self-flocculating genes flo1 when algae receive blue light. With this system, we can collect microalgae at a specific growth period. In addition, we determined the concentration of domestic sewage suitable for engineering microalgae culture through sampling investigation and simulation experiment, and cultivated our algae in it. This can increase the biomass of microalgae and reduce the content of nitrogen and phosphorus in sewage, which further reducing the cost of sewage treatment.
In theory, our algae system could produce cheaper biodiesel than CC-849.
Reference
[1] IEA. Key world energy statistics 2018[R]. Paris: International Energy Agency, 2018
[2] BP. BP Statistical review of world energy 2015[DB/OL]. London
[3] Hill J D, Nelson E O, Tilman D, et al. Environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels[J]. Proceedings of the National Academy of Sciences of the United States of America, 2006, 103(30): 11206-11210.
[4] Ma F, Hanna M A. Biodiesel production: a review[J]. Bioresource Technology, 1999, 70(1): 1-15.
[5] Chisti Y. Biodiesel from microalgae[J]. Biotechnol. Adv.,2007,25(3):294-306.
[6] Mubarak M, Shaija A, Suchithra T V. A review on the extraction of lipid from microalgae for biodiesel production[J]. Algal Research, 2015, 7: 117-123
