The Study Of That Plant Hormones Induce Freshwater Micro-algae Produce Biodiesel And High Value-added Secondary Metabolites

With the rapid development of economic globalizational, the consumption of global energy is rising sharply. However, the fossil energy stored on earth is not limitless and will be exhausted in the near future, which will block the development of human society severely. The pressure is imminent and the key to solving this problem is to find a new, clean and renewable energy. Microalgae have been recognized as the only possible option to completely replace fossil fuels by domestic and foreign experts because of it`s incomparable advantage. Plant hormones(growth regulators) have gotten extensive solicitude because of it`s high efficiency and low cost. Eight different plant growth regulators(ABA, SA, ETH, SPD, GA3, EBR, 6-BA, NAA) are tested to induce Chlorella phyrenoidosa ZF, Chlorella valgaris ZF and Botryococus braunii B12 in this article. And the biomass of cell, lipid production and high value-added secondary metabolites(carotenoids, total soluble protein and polyunsaturated fatty acid) are monitored under the induced conditions. So that we can select the best induced conditions for the algal strains to producing biodiesel and secondary metabolites efficiently. The results showed the 3 microalgae strains were affected by 8 plant regulators varying degrees. 50 mg/L NAA for Chlorella phyrenoidosa ZF, 50 mg/L ABA for Chlorella valgaris ZF, 50 mg/L NAA for Botryococus braunii B12 are the optimal density for growth. The best induced conditions for the promotion of algal strains by synthesising protein quickly are as follows: 0.01 mg/L EBR for Chlorella phyrenoidosa ZF, 10 mg/L SA for Chlorella valgaris ZF, 5 mg/L 6-BA for Botryococus braunii B12.The best induced conditions for the promotion of algal strains by generating carotenoids quickly are as follows: 20 mg/L NAA for Chlorella phyrenoidosa, 5 mg/L 6-BA for Chlorella valgaris ZF, 50 mg/L NAA for Botryococus braunii B12. The best induced conditions for the promotion of algal strains by generating polyunsaturated fatty acids quickly are as follows: 0.05 mg/L NAA for Chlorella phyrenoidosa ZF, 50 mg/L ABA for Chlorella valgaris ZF, 0.01 mg/L ETH for Botryococus braunii B12. The best induced conditions for the promotion of algal strains by accumulating lipid quickly are as follows: 5 mg/L GA3 for Chlorella phyrenoidosa ZF, 20 mg/L ABA for Chlorella valgaris ZF, 15 mg/L GA3 for Botryococus braunii B12.Researching the change of expression patterns of lipid synthesis-related genes(BC、FATA、ACP、SAD、MCTK、FAD、KAS)in algal cells under the best induced conditions by using quantitative real-time PCR.Seven kinds of gene expression of Chlorella phyrenoidosa ZF in 5 mg/L GA3 induction treatment group, Chlorella valgaris ZF in 20 mg/L ABA induction treatment group and Botryococus braunii B12 in 15 mg/L GA3 was significantly higher than the control group. By comparing with the results of lipid production, the increase of genes expression could heighten the lipid production.It can be inferred that the plant growth regulator increase lipid by changing the key genes of lipid synthesis.This study provides a beneficial exploration for micro-algae biodiesel and high value-added secondary metabolites, but also a new idea for microalgae biodiesel industrialization process.