Method for regulating and controlling synthesis of microalgae fatty acid by using long-chain carbon signal substance and application of long-chain carbon signal substance

Abstract

The invention provides a method for regulating and controlling synthesis of microalgae fatty acid by using a long-chain carbon signal substance and application thereof, and the method for regulating and controlling synthesis of microalgae fatty acid by using the long-chain carbon signal substance comprises the following steps: culturing microalgae by using a culture medium to obtain a microalgae culture solution; then, a long-chain carbon signal substance is prepared into a solution, the long-chain carbon signal substance is C14-HSL, and the structural formula of the C14-HSL is shown in the formula I; adding a long-chain carbon signal substance solution into the microalgae culture solution to obtain a mixed solution; and culturing the mixed solution. According to the method, the C14-HSL signal substance is inoculated into the microalgae culture solution, so that the growth of microalgae can be effectively promoted, the relative content and composition of saturated fatty acid, monounsaturated fatty acid and polyunsaturated fatty acid in microalgae cells are influenced, the content of fatty acid related to biodiesel precursor synthesis is increased, and the yield and quality of biodiesel are improved. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of biofuels, and specifically relates to a method and use of a long-chain carbon signal substance to regulate microalgae fatty acid synthesis. Background Art

[0002] Biofuels are environmentally friendly, non-toxic and sustainable, and are expected to play an important role in meeting energy needs and solving energy crises. The commonly used raw materials for biofuel production in the world are mainly divided into three generations. The first generation mainly uses edible crops such as corn and animal fat to ferment and produce bioethanol, thereby producing fuels such as biodiesel. The second generation uses non-agricultural biomass such as lignocellulosic biomass and Masson pine, which are treated with acids, alkalis or microorganisms to produce fermentable sugars, which are fermented by anaerobic microorganisms. The main advantage is the low cost of raw materials. The third generation of biofuel raw materials are microalgae, which contain a large amount of lipids in their biomass and can produce different types of biofuels. However, the first generation of biofuels mainly use edible crops, which will increase production costs and directly compete with food, leading to the food crisis. The second generation of biofuels uses abundant and low-cost lignin as raw materials, which does not compete with food resources, but requires additional acid, alkali and biological pretreatment steps to be effectively utilized. The conversion process is cumbersome and the technical cost is high.

[0003] Microalgae, the third-generation biofuel raw material, has shown great potential in producing oils and converting them into biofuels. Microalgae grow faster than other photosynthetic plants or microorganisms, have lower nutritional requirements, and contain a large amount of lipids such as triglycerides and starch in their biomass, which can produce different types of biofuels. The lipids of microalgae can be used to produce biodiesel, and the carbohydrates can be used to produce bioethanol, biobutanol, biogas and methane. Since microalgae do not contain lignin, no pretreatment process is required and they will not compete with food crops. In addition, biofuels produced using microalgae as raw materials do not release toxic compounds such as sulfur and nitrogen oxides. Biofuels synthesized by microalgae have higher production capacity, lower production costs and less environmental impact. Moreover, microalgae can effectively utilize industrial carbon dioxide and wastewater to synthesize a variety of compounds with economic and medical value, which helps to reduce production costs and bring additional environmental benefits.

[0004] A Chinese patent document with publication number CN107201314A discloses a method for heterotrophic cultivation of microalgae that simultaneously increases biomass and oil content. By carrying out heterotrophic cultivation under specific conditions, the difference between normal conditions of nitrogen-limited phosphorus and normal conditions of both nitrogen and phosphorus is solved, so that the biomass of microalgae is increased by 1.9 times, the oil content is increased by 1.7 times, and reaches 310 mg / (L·d), and the content of C16 and C18 fatty acids exceeds 95%, which can significantly improve the quality of microalgae to prepare biodiesel. However, as an ideal choice for the production of biofuels, although microalgae has many advantages, it still faces problems such as low production efficiency, low efficiency of biomass conversion to fuel, sensitivity to production environment conditions, and low content of C16-C18 fatty acids related to the synthesis of biodiesel precursors. These problems have become obstacles to the large-scale application of microalgae biofuels, and new solutions are urgently needed to improve their production efficiency and economy. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a method and use of a long-chain carbon signal substance to regulate the synthesis of microalgae fatty acids. The C14-HSL signal substance is inoculated into a microalgae culture solution, which can effectively promote the growth of microalgae, affect the relative content and composition of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids in microalgae cells, increase the content of fatty acids related to biodiesel precursor synthesis, and increase the yield and quality of biodiesel.

[0006] In order to solve the above problems, the first aspect of the present invention provides a method for regulating microalgae fatty acid synthesis by long-chain carbon signal substances, comprising the following steps:

[0007] Cultivating microalgae with a culture medium to obtain a microalgae culture solution; then preparing a long-chain carbon signal substance into a solution, wherein the long-chain carbon signal substance is C14-HSL, and the structural formula of C14-HSL is shown in Formula I below; adding the long-chain carbon signal substance solution to the microalgae culture solution to obtain a mixed solution; and then culturing the mixed solution;

[0008]

[0009] Preferably, in the mixed solution, the concentration of the long-chain carbon signal substance C14-HSL is 0 to 1000 nmol / L, and the concentration is not 0 nmol / L.

[0010] Preferably, in the microalgae culture solution, the OD of the microalgae is 680 The value is 0.3~0.5.

[0011] Preferably, the microalgae is Synechocystis PCC6803.

[0012] Preferably, the culture medium comprises: water, 1.2-1.8 g / L sodium nitrate, 0.03-0.05 g / L potassium dihydrogen phosphate, 0.05-0.1 g / L magnesium sulfate heptahydrate, 0.025-0.04 g / L calcium chloride dihydrate, 0.01-0.03 g / L sodium carbonate, EDTANa2 0.0005-0.0015 g / L, citric acid 0.004-0.008 g / L, ammonium ferric citrate 0.004-0.008 g / L, trace elements 0.8-1.2 mL / L; wherein the trace elements include boric acid 2.5-3.2 g / L, manganese chloride tetrahydrate 1.5-2 g / L, zinc sulfate heptahydrate 0.15-0.3 g / L, copper sulfate pentahydrate 0.05-0.1 g / L, sodium molybdate dihydrate 0.2-0.5 g / L, cobalt nitrate hexahydrate 0.03-0.08 g / L; the pH of the culture medium is 7.0-7.4.

[0013] The second aspect of the present invention provides a use of a long-chain carbon signal substance for regulating microalgae fatty acid synthesis, wherein the long-chain carbon signal substance is C14-HSL, and the structural formula of C14-HSL is shown in Formula I below:

[0014]

[0015] Preferably, the fatty acid is at least one of saturated fatty acid, monounsaturated fatty acid and polyunsaturated fatty acid.

[0016] Preferably, the saturated fatty acid is at least one of C12:0, C14:0, C16:0, and C18:0; the monounsaturated fatty acid is at least one of C18:2, C18:2n6t, C18:3, C20:3, C20:4, and C20:5; and the polyunsaturated fatty acid is at least one of C14:1, C16:1, C17:1, C18:1n9c, C18:1n9t, C22:1, and C24:1.

[0017] Preferably, the long-chain carbon signal substance is used to increase the content of saturated fatty acids in microalgae; and / or to reduce the content of monounsaturated fatty acids in microalgae; and / or to increase the content of polyunsaturated fatty acids in microalgae.

[0018] Preferably, the long-chain carbon signal substance is used to promote the synthesis of fatty acids associated with the synthesis of biodiesel precursors in microalgae.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention adopts the long-chain carbon signal substance C14-HSL shown in formula I as the signal substance. The signal substance is added into the culture solution of microalgae, which can effectively promote the growth of microalgae, affect the relative content and composition of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids in microalgae cells, promote the accumulation of saturated fatty acids and polyunsaturated fatty acids, increase the C16:0 component in saturated fatty acids, increase the C16:1 component in monounsaturated fatty acids, reduce the C24:1 component, increase the polyunsaturated fatty acid C18:3 component, and generally increase the C16-C18 fatty acid content related to the synthesis of biodiesel precursors in microalgae cells.

[0021] The scope of action is wide and the effect is significant. Inoculating C14-HSL signal substances into microalgae can increase the content of fatty acids related to biodiesel precursor synthesis and increase the yield and quality of biodiesel. Moreover, C14-HSL signal substances are structural analogs of signal substances from microorganisms. After being added to microalgae, they will enter the body and participate in its metabolism, so there will be no problem of long-term residual time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a diagram showing the effect of adding C14-HSL on the growth of microalgae;

[0023] Figure 2 This is the effect diagram of the addition of C14-HSL on the content of three fatty acids in microalgae;

[0024] Figure 3 This is the effect diagram of the addition of C14-HSL on the composition of saturated fatty acids (SFA) in microalgae;

[0025] Figure 4 This is a diagram showing the effect of the addition of C14-HSL on the composition of polyunsaturated fatty acids (MUFA) in microalgae;

[0026] Figure 5 This is a diagram showing the effect of the addition of C14-HSL on the composition of monounsaturated fatty acids (PUFA) in microalgae;

[0027] Figure 6 This is a diagram showing the effect of adding C14-HSL on promoting the synthesis of C16-C18 fatty acids in microalgae;

[0028] In the above figures, control represents the control group, i.e., the microalgae in comparative example 1 that are not inoculated with the C14-HSL signal substance, and C14-HSL represents the microalgae inoculated with the C14-HSL signal substance. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] A first aspect of an embodiment of the present invention provides a method for regulating microalgae fatty acid synthesis using a long-chain carbon signal substance, comprising the following steps:

[0031] Cultivating microalgae with a culture medium to obtain a microalgae culture solution; then preparing a long-chain carbon signal substance into a solution, wherein the long-chain carbon signal substance is C14-HSL, and the structural formula of C14-HSL is shown in Formula I below; adding the long-chain carbon signal substance solution to the microalgae culture solution to obtain a mixed solution; and then culturing the mixed solution;

[0032]

[0033] The long-chain carbon signal substance C14-HSL was purchased from ZZStandard, with a molecular formula of C18H33NO3, a molecular weight of 311.5, a CAS number of 202284-87-5, and a Chinese name of N-tetradecanoyl-DL-homoserine lactone.

[0034] The present invention adopts the long-chain carbon signal substance C14-HSL shown in the above formula I as the signal substance. The signal substance is added to the culture solution of microalgae, which can effectively promote the growth of microalgae, affect the relative content and composition of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids in microalgae cells, promote the accumulation of saturated fatty acids and polyunsaturated fatty acids, increase the C16:0 component in saturated fatty acids, increase the C16:1 component in monounsaturated fatty acids, reduce the C24:1 component, increase the polyunsaturated fatty acid C18:3 component, and generally increase the C16-C18 fatty acid content related to the synthesis of biodiesel precursors in microalgae cells.

[0035] The scope of action is wide and the effect is significant. Inoculating C14-HSL signal substances into microalgae can increase the content of fatty acids related to biodiesel precursor synthesis and increase the yield and quality of biodiesel. Moreover, C14-HSL signal substances are structural analogs of signal substances from microorganisms. After being added to microalgae, they will enter the body and participate in its metabolism, so there will be no problem of long-term residual time.

[0036] In some embodiments, in the mixed solution, the concentration of the long-chain carbon signal substance is 0 to 1000nmol / L, and the concentration is not 0nmol / L. For example, in the mixed solution, the concentration of the long-chain carbon signal substance can be 100nmol / L, 500nmol / L, and 1000nmol / L. The present invention found that C14-HSL can promote the growth of microalgae at any concentration within the above concentration range. Preferably, in the mixed solution, the concentration of the long-chain carbon signal substance is 500nmol / L. The present invention concludes that the effect of promoting the growth of microalgae is most significant when the concentration of the long-chain carbon signal substance is 500nmol / L. On days 1-5, the growth-promoting effect of the 500nmol / L solution is always lower than that of other concentrations, but the growth-promoting effect on the 7th day exceeds that of other concentrations, indicating that the long-chain molecules enhance their growth-promoting effect through a stable intracellular signal transduction mechanism or a higher affinity with cell receptors.

[0037] In some embodiments, the microalgae is Synechocystis sp. PCC6803. Synechocystis sp. PCC6803 (FACHB-898) is from the Freshwater Algae Culture Bank of the Institute of Hydrobiology, Chinese Academy of Sciences.

[0038] In some embodiments, the culture medium includes: water, sodium nitrate 1.2-1.8 g / L, potassium hydrogen phosphate 0.03-0.05 g / L, magnesium sulfate heptahydrate 0.05-0.1 g / L, calcium chloride dihydrate 0.025-0.04 g / L, sodium carbonate 0.01-0.03 g / L, EDTANa2 0.0005-0.0015 g / L, citric acid 0.004-0.008 g / L, ammonium ferric citrate 0.004-0.008 g / L, trace elements 0.8-1.2 mL / L; wherein the trace elements include boric acid 2.5-3.2 g / L, manganese chloride tetrahydrate 1.5-2 g / L, zinc sulfate heptahydrate 0.15-0.3 g / L, copper sulfate pentahydrate 0.05-0.1 g / L, sodium molybdate dihydrate 0.2-0.5 g / L, cobalt nitrate hexahydrate 0.03-0.08 g / L; the pH of the culture medium is 7.0-7.4. That is, each liter of trace elements contains 2.5-3.2 g of boric acid.

[0039] Preferably, the culture medium is BG11 culture medium, which includes: water, 1.5 g / L sodium nitrate, 0.04 g / L potassium hydrogen phosphate, 0.075 g / L magnesium sulfate heptahydrate, 0.036 g / L calcium chloride dihydrate, 0.02 g / L sodium carbonate, 0.001 g / L EDTANa2, 0.006 g / L citric acid, 0.006 g / L ammonium ferric citrate, and 1 mL / L trace elements; wherein the trace elements include 2.86 g / L boric acid, 1.86 g / L manganese chloride tetrahydrate, 0.22 g / L zinc sulfate heptahydrate, 0.08 g / L copper sulfate pentahydrate, 0.39 g / L sodium molybdate dihydrate, and 0.05 g / L cobalt nitrate hexahydrate. That is, 2.86 g boric acid is contained in each liter of trace elements.

[0040] In some embodiments, in the microalgae culture solution, the OD of the microalgae is 680 Preferably, in the microalgae culture solution, the OD 680 The value is 0.4.

[0041] Preferably, the temperature of the mixed solution during culturing is 20-30° C. Preferably, the temperature of the mixed solution during culturing is 25° C.

[0042] A second aspect of an embodiment of the present invention provides a use of a long-chain carbon signal substance for regulating microalgae fatty acid synthesis, wherein the long-chain carbon signal substance is C14-HSL, and the structural formula of C14-HSL is shown in Formula I below:

[0043]

[0044] The present invention finds that inoculating C14-HSL signal substances into microalgae can effectively promote the growth of microalgae and affect the relative content and composition of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids in microalgae cells.

[0045] In some embodiments, the fatty acid is at least one of a saturated fatty acid, a monounsaturated fatty acid, and a polyunsaturated fatty acid.

[0046] Preferably, the long-chain carbon signal substance is used to increase the content of saturated fatty acids in microalgae; and / or to reduce the content of monounsaturated fatty acids in microalgae; and / or to increase the content of polyunsaturated fatty acids in microalgae. The present invention finds that the long-chain carbon signal substance C14-HSL can promote the accumulation of saturated fatty acids and polyunsaturated fatty acids.

[0047] In some embodiments, the saturated fatty acid is at least one of C12:0, C14:0, C16:0, and C18:0; the monounsaturated fatty acid is at least one of C18:2, C18:2n6t, C18:3, C20:3, C20:4, and C20:5; and the polyunsaturated fatty acid is at least one of C14:1, C16:1, C17:1, C18:1n9c, C18:1n9t, C22:1, and C24:1. In C12:0, 12 represents the number of carbon atoms in the fatty acid, and 0 represents the number of carbon-carbon double bonds in the fatty acid. Therefore, the fatty acid corresponding to C12:0 is n-dodecanoic acid, i.e., lauric acid. The "C18" in C18:1n9c indicates that the fatty acid molecule contains 18 carbon atoms, "1" indicates that it contains one carbon-carbon double bond (C=C), and "n9c" indicates that the double bond is located on the 9th carbon atom and is in the cis configuration. The abbreviations of other fatty acids are applicable by analogy. The above abbreviations are the naming rules in the industry known to those skilled in the art.

[0048] Preferably, the long-chain carbon signal substance is used to promote the synthesis of fatty acids associated with the synthesis of biodiesel precursors in microalgae.

[0049] The present invention has found that long-chain carbon signal substances can increase the C16:0 component in saturated fatty acids, increase the C16:1 component in monounsaturated fatty acids, reduce the C24:1 component, and increase the C18:3 component of polyunsaturated fatty acids in microalgae, thereby generally increasing the content of C16-C18 fatty acids related to the synthesis of biodiesel precursors in microalgae cells. The action range is wide and the effect is significant.

[0050] Example 1

[0051] The method of regulating microalgae fatty acid synthesis by long-chain carbon signal substances of this embodiment comprises the following steps:

[0052] (1) Culture medium preparation

[0053] Measure 1000 mL of distilled water into a 1000 mL beaker, and use a pipette to add the following nutrient reserve solution in sequence: sodium nitrate (150 g / L, 10 mL), dipotassium hydrogen phosphate (4 g / L, 10 mL), magnesium sulfate heptahydrate (7.5 g / L, 10 mL), calcium chloride dihydrate (3.6 g / L, 10 mL), sodium carbonate (2 g / L, 10 mL), EDTANa2 (0.1 g / L, 10 mL), citric acid (0.6 g / L, 10 mL), ammonium ferric citrate (0.6 g / L, 10 mL), and trace element A5 (1 mL). Trace elements A5 include: boric acid (2.86 g / L), manganese chloride tetrahydrate (1.86 g / L), zinc sulfate heptahydrate (0.22 g / L), copper sulfate pentahydrate (0.08 g / L), sodium molybdate dihydrate (0.39 g / L), cobalt nitrate hexahydrate (0.05 g / L). After each nutrient is added, it needs to be shaken to ensure adequate mixing. After the culture medium is prepared, the pH value is adjusted to between 7.0 and 7.4, and 2 mol / L HCl or NaOH is used as needed. Finally, the culture medium is placed in an autoclave at 121°C to 123°C and sterilized with high-pressure steam for 15 to 20 minutes.

[0054] (2) Microalgae cultivation

[0055] The selected Synechocystis sp. PCC6803 was inoculated into the above-mentioned BG11 medium and cultured in an artificial climate incubator for 7 days until its OD 680 was 0.4, and the culture medium of Synechocystis PCC6803 was used for subsequent experiments.

[0056] (3) Signal substance inoculation

[0057] The signal substance C14-HSL was prepared into a 24 mmol / L C14-HSL solution using ethanol as the dissolution medium of the signal substance. 680 1.25 μL of C14-HSL solution was added to the microalgae suspension with a value of 0.4, and mixed thoroughly with the culture solution so that the concentration of C14-HSL in the mixed solution was 100 nmol / L. The mixed solution was then cultured in an artificial climate chamber.

[0058] Example 2

[0059] The method for regulating microalgae fatty acid synthesis by long-chain carbon signal substances in this embodiment is the same as that in Example 1, except that 300 mL OD 680 6.25 μL of 24 mmol / L C14-HSL solution was added to the microalgae suspension with a value of 0.4, and the mixture was fully mixed with the culture solution so that the concentration of C14-HSL in the mixed solution was 500 nmol / L.

[0060] Example 3

[0061] The method of regulating microalgae fatty acid synthesis by long-chain carbon signal substances in this embodiment is the same as that in Example 1. 300 mL OD 680 12.5 μL of 24 mmol / L C14-HSL solution was added to the microalgae suspension with a value of 0.4, and the mixture was fully mixed with the culture solution so that the concentration of C14-HSL in the mixed solution was 1000 nmol / L.

[0062] Comparative Example 1

[0063] The method of this comparative example and the remaining steps are the same as those of Example 1, except that the concentration of the C14-HSL solution is 0 nmol / L, that is, the C14-HSL solution is not added to the microalgae suspension.

[0064] Example 4 Determination of microalgae growth rate

[0065] The growth rate of microalgae was determined using visible spectrophotometry. The microalgae culture solution was first shaken thoroughly before the experiment to ensure consistency between samples. To ensure the accuracy of the experiment, BG11 culture medium without inoculation of the microalgae composition was used as a blank control, the UV spectrophotometer was zero-calibrated, and the measurement wavelength was set to 680nm. The spectrophotometric value at 680nm was measured continuously for 7 days to characterize the growth rate of the microalgae.

[0066] By comparing the spectrophotometric values ​​of the microalgae composition from day 1 to day 7 and plotting them, we can obtain the effect of inoculating the C14-HSL signal substance on the growth rate of the microalgae. Figure 1 shown.

[0067] like Figure 1 As shown, C14-HSL promoted the growth of microalgae at all concentrations, among which 500nmol / L had the most significant effect. On days 1-5, the growth-promoting effect of the 500nmol / L solution was always lower than that of other concentrations, and the growth-promoting effect on day 7 exceeded that of other concentrations, indicating that long-chain molecules can enhance their growth-promoting effects through stable intracellular signal transduction mechanisms or higher affinity with cell receptors.

[0068] Example 5 Determination of fatty acid composition and biodiesel precursor content

[0069] The composition of microalgae fatty acids obtained in Example 3 was analyzed using the KOH methanol-water method. First, total lipid extraction: centrifugal collection of algae cells (4000rpm, 20min), 500mg of algae cells added to 10mL of methanol / CH2Cl2 (1:3) mixed solution, shake well; constant temperature below 30°C ultrasonic extraction for 10min. Take out the centrifuge tube, centrifuge it in a centrifuge (1800rpm, 10min), collect the supernatant, repeat 3 times; the extract liquid is blown dry with nitrogen to obtain total lipids. Then, the extracted total lipids are mixed with a methanol-water solution containing 5%-6% KOH and incubated at 60°C for 2 hours. After the incubation, cool to room temperature, and treat the mixture with chloroform-n-hexane solution and diluted HCl solution (concentration of 6mol / L) to separate fatty acids. Repeat the saponification reaction three times to ensure sufficient reaction. The organic phase is collected after each reaction, and the solvent is removed by a rotary evaporator. After saponification, 14% BF3-methanol solution was added to the reaction system for methylation to produce fatty acid methyl esters. The methylated samples were then qualitatively and quantitatively analyzed using an Agilent 7890B gas chromatograph and 7000C mass spectrometer (GC-MS) equipped with a fused silica capillary column. When evaluating the potential production of biodiesel, the content of C16-C18 long-chain fatty acids (mainly palmitic acid, stearic acid and oleic acid) is considered to be an important indicator for judging the content of biodiesel. This experiment determined the relative content of C16-C18 fatty acids in the sample and calculated the content of biodiesel precursors, thereby estimating the potential for microalgae biodiesel synthesis.

[0070] By analyzing the effect of C14-HSL on the content and composition of fatty acids in microalgae, we can conclude the effect of inoculation of C14-HSL signal substances on the fatty acid composition of microalgae and biodiesel production. Figure 2-6 shown.

[0071] like Figure 2 As shown in the figure, the addition of C14-HSL led to an increase in the content of saturated fatty acids (SFA) in microalgae. Compared with the monounsaturated fatty acid (MUFA) content of 9.44 mg / g in the control group, the MUFA content after C14-HSL treatment was reduced to 6.26 mg / g, indicating that signal substances can induce microalgae to preferentially synthesize SFA rather than MUFA. Compared with 18.63 mg / g in the control group, C14-HSL treatment significantly increased the polyunsaturated fatty acid (PUFA) content to 19.54 mg / g, indicating that C14-HSL can affect the fatty acid composition of microalgae by regulating the lipid metabolism process, especially in the accumulation of SFA and PUFA.

[0072] like Figure 3As shown in the figure, the addition of C14-HSL affected the composition of SFA. The composition of SFA was mainly C16:0, and C12:0 and C18:0 showed a decreasing trend under the action of signal substances, indicating that signal substances promoted the synthesis of specific SFA and played a specific role in regulating the fatty acid composition of microalgae.

[0073] like Figure 4 As shown in the figure, the addition of C14-HSL affected the composition of MUFA. The main components of MUFA are C16:1 and C24:1. Under the action of C14-HSL, the content of C16:1 in microalgae increased from 20.36% in the control group to 39.05%, and the content of C24:1 decreased from 45.88% in the control group to 23.99%.

[0074] like Figure 5 As shown in the figure, the addition of C14-HSL affected the composition of PUFA. C18:2 is the main component of PUFA in microalgae. Under the action of C14-HSL, C18:2 decreased from 24.27% in the control group to 23.8%, and C18:3 increased by 14.52% compared with the control group, indicating the specific role of signal molecules in the lipid synthesis and metabolic regulation of microalgae.

[0075] like Figure 6 As shown, the addition of C14-HSL affects the synthesis of biodiesel precursor-related fatty acids in microalgae. In the control group, the content of C16-C18 fatty acids was 34.5 mg / g. After C14-HSL treatment, the content of C16-C18 fatty acids in microalgae increased to 37.07 mg / g, indicating that C14-HSL can promote the synthesis of fatty acids related to the synthesis of biodiesel precursors.

[0076] It can be seen that the C14-HSL signal substance of the present invention effectively changes the relative content and composition of fatty acids in microalgae cells, promotes the synthesis of fatty acids related to biodiesel precursor synthesis, thereby effectively increasing the yield and quality of biodiesel, and further improving the utilization rate of biofuels.

[0077] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for regulating microalgae fatty acid synthesis by long-chain carbon signal substances, characterized in that: The following steps are involved: Cultivating microalgae with a culture medium to obtain a microalgae culture solution; then preparing a long-chain carbon signal substance into a solution, wherein the long-chain carbon signal substance is C14-HSL, and the structural formula of C14-HSL is shown in Formula I below; adding the long-chain carbon signal substance solution to the microalgae culture solution to obtain a mixed solution; and then culturing the mixed solution; 2. The method for regulating microalgae fatty acid synthesis by long-chain carbon signal substances according to claim 1, characterized in that: In the mixed solution, the concentration of the long-chain carbon signal substance C14-HSL is 0 to 1000 nmol / L, and the concentration is not 0 nmol / L.

3. The method for regulating microalgae fatty acid synthesis by long-chain carbon signal substances according to claim 1, characterized in that: In the microalgae culture solution, the OD 680 The value is 0.3~0.

5.

4. The method for regulating microalgae fatty acid synthesis by long-chain carbon signal substances according to claim 1, characterized in that: The microalgae is Synechocystis PCC6803.

5. The method for regulating microalgae fatty acid synthesis by long-chain carbon signal substances according to claim 1, characterized in that: The culture medium comprises: water, 1.2-1.8 g / L sodium nitrate, 0.03-0.05 g / L dipotassium hydrogen phosphate, 0.05-0.1 g / L magnesium sulfate heptahydrate, 0.025-0.04 g / L calcium chloride dihydrate, 0.01-0.03 g / L sodium carbonate, EDTANa2 0.0005-0.0015 g / L, citric acid 0.004-0.008 g / L, ammonium ferric citrate 0.004-0.008 g / L, trace elements 0.8-1.2 mL / L; wherein the trace elements include boric acid 2.5-3.2 g / L, manganese chloride tetrahydrate 1.5-2 g / L, zinc sulfate heptahydrate 0.15-0.3 g / L, copper sulfate pentahydrate 0.05-0.1 g / L, sodium molybdate dihydrate 0.2-0.5 g / L, cobalt nitrate hexahydrate 0.03-0.08 g / L; the pH of the culture medium is 7.0-7.

4.

6. A use of a long-chain carbon signal substance for regulating microalgae fatty acid synthesis, wherein the long-chain carbon signal substance is C14-HSL, and the structural formula of C14-HSL is shown in Formula I below:

7. The use according to claim 6, characterized in that: The fatty acid is at least one of saturated fatty acid, monounsaturated fatty acid and polyunsaturated fatty acid.

8. The use according to claim 7, characterized in that: The saturated fatty acid is at least one of C12:0, C14:0, C16:0, and C18:0; the monounsaturated fatty acid is at least one of C18:2, C18:2n6t, C18:3, C20:3, C20:4, and C20:5; and the polyunsaturated fatty acid is at least one of C14:1, C16:1, C17:1, C18:1n9c, C18:1n9t, C22:1, and C24:

1.

9. The use according to claim 7, characterized in that: The long-chain carbon signal substance is used to increase the content of saturated fatty acids in microalgae; and / or to reduce the content of monounsaturated fatty acids in microalgae; and / or to increase the content of polyunsaturated fatty acids in microalgae.

10. The use according to claim 6, characterized in that: The long-chain carbon signal substance is used to promote the synthesis of fatty acids related to the synthesis of biodiesel precursors in microalgae.

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