CN104560357A - Method for synchronously extracting microalgal oil and microalgal polysaccharide - Google Patents

Abstract

The present invention relates to the technical field of microalgae biorefining, in particular to a method for simultaneously extracting microalgae oil and microalgae polysaccharides, comprising the following steps: step 1, treating microalgae with plant cell wall degrading enzymes to obtain microalgae pretreated products ; Step 2, treating the microalgae pretreatment at a temperature of 80-120°C and a pressure of 0.05-0.25MPa for 10-30min to obtain a microalgae secondary pretreatment, and the microalgae secondary pretreatment The processed product is used to extract microalgae oil and microalgae polysaccharide. The method of the invention improves the reaction conditions for extracting microalgae oil and microalgae polysaccharide, fully utilizes microalgae raw materials to the greatest extent, extracts as much microalgae polysaccharide and microalgae oil as possible, reduces production cost, and is suitable for large-scale production.

Description

A method for simultaneously extracting microalgae oil and microalgae polysaccharide

technical field

The invention belongs to the technical field of microalgae biorefining, and specifically relates to a method for simultaneously extracting microalgae oil and microalgae polysaccharides. While extracting microalgae oil, the multi-component extraction of intracellular substances is increased, and the coupling production of microalgal polysaccharides.

Background technique

Microalgae is a kind of aquatic photoautotrophic microorganism, which can use light energy, absorb CO ₂ for cell growth, and synthesize a large amount of carbohydrates, including: oil, protein, polysaccharide, pigment, etc. Microalgae oil can be processed into biodiesel, which is regarded as a clean energy source. Especially in the case of increasing shortage of fossil fuels such as oil and natural gas, the issue of using microalgae as a biofuel has attracted widespread attention from various countries. At the same time, microalgal proteins and polysaccharides have important application value in food, medicine and other fields. Therefore, various countries have launched research on the comprehensive utilization of microalgae. However, the vast majority of microalgae oils, proteins, polysaccharides and other substances exist in the cells. How to effectively break the wall of algae cells to extract intracellular substances is an important key to the application of microalgae industry.

At present, there are generally two ways to extract intracellular substances by breaking the wall of microalgae: mechanical breaking and solvent extraction. Mechanical wall-breaking methods include grinding, ultrasonic waves, etc. All of these wall-breaking methods have a huge problem, that is, high energy consumption, which limits further use in industrial production; while solvent extraction is easy to pollute the environment. In addition, the above-mentioned extraction methods all need to dry or concentrate the microalgae, and the concentration and drying of the microalgae biomass consume a lot of energy. A single extraction of intracellular oil or protein also hinders the development of the microalgae industry. Therefore, the low-cost extraction of multi-component substances in microalgae cells is the bottleneck for the comprehensive utilization of microalgae.

Water extraction was tested as a method that can directly extract oil, protein or other components of microalgae from wet algae cells. For example, Carl Safi et al. used methods such as high-pressure homogenization, ultrasonication, and grinding to extract proteins from cell walls of Spirulina platensis, Chlorella, Haematococcus pluvialis, and Porphyridum (Carl Safi, Alina VioletaUrsu, Celine Laroche , et al. Aqueous extraction of proteins from microalgae: effect of different cell disruption methods. Algal Research. 2014; 3: 61-65). The results showed that the protein extraction rate of high-pressure homogenization was the highest, followed by chemical solvent extraction, but only a single protein was extracted and other components in the microalgae were discarded. Chinese patent 200810240949.3 proposes a technology for simultaneously extracting oil and protein from microalgae, the principle of which is to use high-pressure steam to break the wall. The method is to place the algae liquid in a reaction tank, contact with hot saturated steam, continue heating and maintain 110-140° C. for 3-30 minutes, and realize cell wall rupture. However, in actual use, the method uses high temperature (up to 140° C.) and long time (up to 30 minutes), consumes a lot of energy, and is likely to cause chemical reactions and deterioration of intracellular substances under high temperature conditions. Chinese patent CN02153296.6 extracts a method for breaking seaweed cells by steam explosion, which requires maintaining the pressure in the steam explosion tank to 0.8-1.5 MPa and requiring instant release. In the process of use, the high pressure and high energy consumption are also easy to cause the deterioration of intracellular substances; at the same time, the instantaneous decompression is easy to cause liquid splashing, resulting in sample loss and safety problems.

Contents of the invention

One of the objectives of the present invention is to provide a method for simultaneously extracting microalgae oil and microalgae polysaccharides, which reduces the reaction conditions of high temperature and high pressure under the action of plant cell wall-breaking enzymes such as the same cellulase, and at the same time improves microalgae. The extraction rate of algae polysaccharides and microalgae oils improves the reaction conditions, maximizes the use of microalgae raw materials, extracts as much as possible of microalgae polysaccharides and microalgae oils, and reduces production costs.

In order to achieve the above object and some other objects, the technical solutions provided by the present invention are:

A method for extracting microalgae oil and microalgae polysaccharide simultaneously, is characterized in that, comprises the following steps:

Step 1, treating the microalgae with a plant cell wall degrading enzyme to obtain a microalgae pretreatment;

Step 2: Treat the microalgae pretreatment at a temperature of 80-120° C. and a pressure of 0.05-0.25 MPa for 10-30 minutes to obtain a microalgae secondary pretreatment, and the microalgae secondary pretreatment It is used to extract microalgae oil and microalgae polysaccharide.

In the above scheme, the microalgae can directly use the microalgae liquid or wet algae mud to extract the polysaccharides and oils in the microalgae cells, which reduces the drying process of the microalgae biomass and reduces the extraction cost; Compared with the method of steam explosion, the reaction conditions reduce the temperature and pressure of the high-temperature and high-pressure reactor, which helps to reduce energy consumption; and increases the yield of microalgae polysaccharides, and the process method is easy, which is conducive to the realization of microalgae oil and the scale-up application of the polysaccharide polygeneration process.

Preferably, in the second step, the microalgae pretreatment product is obtained by treating the microalgae pretreatment product at a temperature of 110-120° C. and a pressure of 0.13-0.15 MPa for 10-30 min.

Preferably, wherein, in the second step, the microalgae pretreatment product is obtained by treating the microalgae pretreatment product at a temperature of 120° C. and a pressure of 0.15 MPa for 10-30 min.

Preferably, the addition amount of the plant cell wall degrading enzyme in the step is 0.2-1% of the mass percentage of the microalgae.

Preferably, wherein, in the step 1, the pH value of the mixed treatment of the microalgae with the plant cell wall degrading enzyme is 5.2-6.0, the reaction temperature is 20-35°C, and the reaction is 2-5h.

Preferably, wherein the plant cell wall degrading enzymes include cellulase and lysozyme.

Preferably, wherein, comprising the following steps:

Step 3, adding an organic extractant to the microalgae secondary pretreatment product to extract microalgae oil, and separating a microalgae polysaccharide liquid rich in microalgae polysaccharide;

Step 4, filtering the microalgae polysaccharide solution to remove microalgae cell residues;

Step 5, adding trichloroacetic acid to the microalgae polysaccharide solution to precipitate and remove protein and nucleic acid impurities to obtain a secondary microalgae polysaccharide solution;

Step 6: centrifuge the secondary microalgae polysaccharide liquid, collect the supernatant, and then add ethanol with a volume fraction of 80% therein to react until the precipitation no longer increases, and obtain the microalgae crude polysaccharide.

Preferably, wherein, the organic extractant is chloroform or ether.

Preferably, the microalgae include one or more of Dunaliella salina, Nannochloropsis, Chlorella or Scenedesmus obliquus.

Preferably, in the step 6, centrifuge the secondary microalgae polysaccharide liquid, collect the supernatant, and then add ethanol with a volume fraction of 100% to it to react until the precipitation no longer increases, so as to obtain the microalgae crude polysaccharide .

The beneficial effects of the present invention are:

In the method of the present invention, the microalgae used directly uses the microalgae liquid or wet algae mud to extract the intracellular polysaccharides and oils of the microalgae, which reduces the drying process of the microalgae biomass and reduces the extraction cost;

In the method of the present invention, in the process of further processing the microalgae pretreatment, its reaction conditions reduce the temperature and pressure of the high-temperature and high-pressure reactor compared with the method of steam explosion, which helps to reduce energy consumption;

In the method of the present invention, not only the yield of microalgae polysaccharide is increased, the process method is easy, but also it is beneficial to realize the enlarged application of microalgae oil and polysaccharide polygeneration process;

In summary, the method of the present invention improves the reaction conditions for extracting microalgae oils and microalgae polysaccharides, makes full use of microalgae raw materials to the greatest extent, extracts as much microalgae polysaccharides and microalgae oils as possible, reduces production costs, and is suitable for Mass production.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments, so that those skilled in the art can implement it with reference to the description.

Example 1

A method for extracting microalgae oil and microalgae polysaccharide simultaneously, is characterized in that, comprises the following steps:

Step 1, treating Dunaliella salina with cellulase to obtain Dunaliella salina pretreatment; wherein, the added amount of the cellulase accounts for 0.2% of the mass percentage of the microalgae; the microalgae is treated with cellulase The pH value of the mixed treatment is 5.2, the reaction temperature is 20°C, and the reaction is 2h;

Step 2, treating the Dunaliella salina pretreatment at a temperature of 80° C. and a pressure of 0.05 MPa for 10 minutes to obtain a Dunaliella salina secondary pretreatment, and using the Dunaliella salina secondary pretreatment for Extract microalgae oil and microalgae polysaccharide;

Step 3, adding chloroform to the secondary pretreatment of Dunaliella salina to extract microalgae oil, and separating the Dunaliella salina polysaccharide liquid rich in microalgae polysaccharide;

Step 4, filtering the Dunaliella salina polysaccharide solution to remove Dunaliella salina cell residues;

Step 5, adding trichloroacetic acid to the Dunaliella salina polysaccharide solution to precipitate and remove protein and nucleic acid impurities to obtain a secondary Dunaliella salina polysaccharide solution;

Step 6: Centrifuge the secondary Dunaliella salina polysaccharide liquid, collect the supernatant, and then add ethanol with a volume fraction of 80% to it to react until the precipitation no longer increases, and obtain the microalgae crude polysaccharide.

In the above scheme, the microalgae can directly use the microalgae liquid or wet algae mud to extract the polysaccharides and oils in the microalgae cells, which reduces the drying process of the microalgae biomass and reduces the extraction cost; Compared with the method of steam explosion, the reaction conditions reduce the temperature and pressure of the high-temperature and high-pressure reactor, which helps to reduce energy consumption; and increases the yield of microalgae polysaccharides, and the process method is easy, which is conducive to the realization of microalgae oil and the scale-up application of the polysaccharide polygeneration process.

Example 2

A method for extracting microalgae oil and microalgae polysaccharide simultaneously, is characterized in that, comprises the following steps:

Step 1, treating Nannochloropsis algae with a lytic enzyme to obtain a Nannochloropsis pretreated product; wherein, the added amount of the lytic enzyme accounts for 0.4% of the mass percentage of the microalgae; the microalgae is treated with a lytic enzyme The pH value of the wall enzyme mixed treatment is 5.4, the reaction temperature is 25°C, and the reaction is 2.5h;

Step 2. Treat the Nannochloropsis pretreated product at a temperature of 90° C. and a pressure of 0.05 MPa for 15 minutes to obtain a secondary pretreated product of Nannochloropsis, and treat the Nannochloropsis secondary pretreated product The product is used to extract microalgae oil and microalgae polysaccharide;

Step 3, adding ether to the Nannochloropsis secondary pretreatment product to extract the microalgae oil, and separating the Nannochloropsis polysaccharide liquid rich in microalgae polysaccharide;

Step 4, filtering the Nannochloropsis polysaccharide liquid to remove the Nannochloropsis cell residue;

Step 5, adding trichloroacetic acid to the Nannochloropsis polysaccharide liquid to precipitate and remove protein and nucleic acid impurities to obtain a secondary Nannochloropsis polysaccharide liquid;

Step 6: Centrifuge the secondary Nannochloropsis polysaccharide liquid, collect the supernatant, and then add ethanol with a volume fraction of 100% therein to react until the precipitation no longer increases, and obtain the microalgae crude polysaccharide.

In the above scheme, the microalgae can directly use the microalgae liquid or wet algae mud to extract the polysaccharides and oils in the microalgae cells, which reduces the drying process of the microalgae biomass and reduces the extraction cost; Compared with the method of steam explosion, the reaction conditions reduce the temperature and pressure of the high-temperature and high-pressure reactor, which helps to reduce energy consumption; and increases the yield of microalgae polysaccharides, and the process method is easy, which is conducive to the realization of microalgae oil and the scale-up application of the polysaccharide polygeneration process.

Example 3

A method for extracting microalgae oil and microalgae polysaccharide simultaneously, is characterized in that, comprises the following steps:

Step 1, the chlorella is treated with cellulase to obtain the chlorella pretreatment; wherein, the added amount of the cellulase accounts for 0.6% of the mass percentage of the microalgae; the microalgae is treated with the cellulase The pH value of the mixed treatment is 5.6, the reaction temperature is 30°C, and the reaction is 3.5h;

Step 2. Treat the chlorella pretreatment for 30 minutes at a temperature of 100° C. and a pressure of 0.15 MPa to obtain a secondary chlorella pretreatment, and use the chlorella secondary pretreatment for Extract microalgae oil and microalgae polysaccharide;

Step 3, adding chloroform to the secondary pretreatment of chlorella to extract microalgae oil, and separating

Isolate the chlorella polysaccharide liquid rich in microalgae polysaccharide;

Step 4, filtering the chlorella polysaccharide solution to remove the chlorella cell residue;

Step 5, adding trichloroacetic acid to the chlorella polysaccharide solution to precipitate and remove protein and nucleic acid impurities to obtain a secondary chlorella polysaccharide solution;

Step 6: centrifuge the secondary chlorella polysaccharide liquid, collect the supernatant, and then add ethanol with a volume fraction of 80% therein to react until the precipitation no longer increases, and obtain the microalgae crude polysaccharide.

In the above scheme, the microalgae can directly use the microalgae liquid or wet algae mud to extract the polysaccharides and oils in the microalgae cells, which reduces the drying process of the microalgae biomass and reduces the extraction cost; Compared with the method of steam explosion, the reaction conditions reduce the temperature and pressure of the high-temperature and high-pressure reactor, which helps to reduce energy consumption; and increases the yield of microalgae polysaccharides, and the process method is easy, which is conducive to the realization of microalgae oil and the scale-up application of the polysaccharide polygeneration process.

Example 4

A method for extracting microalgae oil and microalgae polysaccharide simultaneously, is characterized in that, comprises the following steps:

Step 1, treating Scenedesmus obliquus with plant cell wall degrading enzyme to obtain Scenedesmus obliquus pretreatment; wherein, the added amount of the plant cell wall degrading enzyme accounts for 0.8% of the mass percentage of the microalgae; the microalgae The pH value of the mixed treatment with plant cell wall degrading enzyme is 5.8, the reaction temperature is 35°C, and the reaction is 4h;

Step 2, treating the pretreated Scenedesmus obliquus at a temperature of 110° C. and a pressure of 0.20 MPa for 30 minutes to obtain a secondary pretreated Scenedesmus obliquus, and treating the Scenedesmus obliques secondary pretreatment The product is used to extract microalgae oil and microalgae polysaccharide;

Step 3, adding an organic extractant to the secondary pretreatment of Scenedesmus obliquus to extract microalgae oil, and separating Scenedesmus obliquus polysaccharide liquid rich in microalgae polysaccharide;

Step 4, filtering the Scenedesmus obliquus polysaccharide solution to remove Scenedesmus obliquus cell residues;

Step 5, adding trichloroacetic acid to the polysaccharide solution of Scenedesmus obliquus to precipitate and remove protein and nucleic acid impurities to obtain a secondary polysaccharide solution of Scenedesmus obliquus;

Step 6: centrifuge the secondary Scenedesmus obliquus polysaccharide solution, collect the supernatant, and then add ethanol with a volume fraction of 100% therein to react until the precipitation no longer increases, so as to obtain the microalgae crude polysaccharide.

In the above scheme, the microalgae can directly use the microalgae liquid or wet algae mud to extract the polysaccharides and oils in the microalgae cells, which reduces the drying process of the microalgae biomass and reduces the extraction cost; Compared with the method of steam explosion, the reaction conditions reduce the temperature and pressure of the high-temperature and high-pressure reactor, which helps to reduce energy consumption; and increases the yield of microalgae polysaccharides, and the process method is easy, which is conducive to the realization of microalgae oil and the scale-up application of the polysaccharide polygeneration process.

Example 5

A method for extracting microalgae oil and microalgae polysaccharide simultaneously, is characterized in that, comprises the following steps:

Step 1, treating Dunaliella salina with a lytic enzyme to obtain a pretreated Dunaliella salina; wherein, the added amount of the lytic enzyme accounts for 1% of the mass percentage of the microalgae; the microalgae is treated with a lytic enzyme The pH value of the mixed treatment is 6.0, the reaction temperature is 35°C, and the reaction is 5h;

Step 2, treating the Dunaliella salina pretreatment at a temperature of 80° C. and a pressure of 0.25 MPa for 20 minutes to obtain a Dunaliella salina secondary pretreatment, and using the Dunaliella salina secondary pretreatment for Extract microalgae oil and microalgae polysaccharide;

Step 3, adding an organic extractant to the secondary pretreatment of Dunaliella salina to extract microalgae oil, and separating the Dunaliella salina polysaccharide liquid rich in microalgae polysaccharide;

Step 4, filtering the Dunaliella salina polysaccharide solution to remove Dunaliella salina cell residues;

Step 5, adding trichloroacetic acid to the Dunaliella salina polysaccharide solution to precipitate and remove protein and nucleic acid impurities to obtain a secondary Dunaliella salina polysaccharide solution;

Step 6: Centrifuge the secondary Dunaliella salina polysaccharide liquid, collect the supernatant, and then add ethanol with a volume fraction of 80% to it to react until the precipitation no longer increases, and obtain the microalgae crude polysaccharide.

In the above scheme, the microalgae can directly use the microalgae liquid or wet algae mud to extract the polysaccharides and oils in the microalgae cells, which reduces the drying process of the microalgae biomass and reduces the extraction cost; Compared with the method of steam explosion, the reaction conditions reduce the temperature and pressure of the high-temperature and high-pressure reactor, which helps to reduce energy consumption; and increases the yield of microalgae polysaccharides, and the process method is easy, which is conducive to the realization of microalgae oil and the scale-up application of the polysaccharide polygeneration process.

Apply the method of the present invention to carry out the extraction of microalgae polysaccharide and microalgae oil under laboratory conditions, method steps are as follows:

Embodiment 6:

1) Adjust the pH to 6.0 with 75mL Dunaliella salina with NaAc;

2) The experimental group added 2.0% microalgae lysozyme (T.harzianum L1412), treated at 37°C for 2 hours as the experimental group ① and 37°C for 6 hours as the experimental group ②; the control group did not add;

3) Put the experimental group and the control group in high-temperature and high-pressure reactors respectively. Among them, the reaction temperature of the experimental group ① is 120°C, the reaction temperature of the experimental group ② is 95°C, and the reaction temperature of the control group is 160°C. The above three groups are all treated 30min;

4) Add 150 mL of chloroform to the algae slurry obtained in the above experiment, shake it at 120 rpm at 37°C for 60 min, and collect the oil phase and water phase by centrifugation;

5) Use a rotary evaporator to recover and reuse the chloroform from the oil phase to obtain crude oil from microalgae, and weigh it;

6) Add 80% TCA trichloroacetic acid to the water phase to a concentration of 10%, let stand overnight at 4°C, and collect the supernatant by centrifugation;

7) Add 3 times the volume of absolute ethanol to the supernatant to precipitate the supernatant, centrifuge, and take the precipitate as polysaccharide extract.

The results are shown in Table 1 below:

The oil content of the Dunaliella salina strain is 23.22% after the traditional chloroform-methanol oil extraction method. It can be calculated that:

The oil extraction rate of microalgae in the control group was 14.51%/23.22%=62.5%;

Experimental group ① The oil extraction rate of microalgae was 22.83%/23.22% = 98.3%;

The oil extraction rate of microalgae in experimental group ② was 10.26%/23.22%=44.2%.

Example 7

1) Add 1g of dry algae powder to 50mL of water according to the ratio of 1:50, and adjust the pH to 5.0 with acetic acid;

2) Add 0.2% microalgae lysozyme (T.harzianum L1412) to the experimental group, and treat at 37°C for 4 hours, while the control group does not add;

3) The control group was placed in a high-temperature and high-pressure reactor to adjust the temperature to 160°C, and the reaction temperature of the treatment group was 120°C for 2 hours, and both were treated for 30 minutes;

4) Add 150 mL of chloroform to the algae slurry obtained in the above experiment, shake it at 120 rpm at 37°C for 60 min, and collect the oil phase and water phase by centrifugation;

5) Use a rotary evaporator to recover and reuse the chloroform from the oil phase to obtain crude oil from microalgae, and weigh it;

6) Add 80% TCA to the water phase to a concentration of 10%, let it stand overnight at 4°C, and collect the supernatant by centrifugation;

7) Add 3 times the volume of absolute ethanol to the supernatant to precipitate the supernatant, centrifuge, and take the precipitate as polysaccharide extract.

The results are shown in Table 2 below:

The oil content of Scenedesmus obliquus is 35.6% through traditional chloroform-methanol oil extraction, which can be calculated as follows:

The oil extraction rate of microalgae in the control group was 22.82%/35.6%=64.1%;

The oil extraction rate of the microalgae in the experimental group was 28.64%/35.6%=80.4%.

Show by the data in above-mentioned test table 1 and table 2 and oil extraction rate data, the method for simultaneously extracting microalgae oil and microalgae polysaccharide provided by the present invention can extract microalgae polysaccharide and microalgae oil simultaneously, and guarantee oil content At the same time, the extraction rate of the polysaccharide is increased; the method provided by the invention can effectively reduce the temperature and pressure of the reaction kettle and shorten the reaction time, greatly reducing the extraction energy consumption.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the use listed in the specification and implementation, it can be applied to various fields suitable for the present invention, and it can be easily understood by those skilled in the art Therefore, the invention is not limited to the specific details and embodiments shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims (10)

1. extract a method for microalgae grease and microalgal polysaccharide simultaneously, it is characterized in that, comprise the following steps:

Step one, by micro-algae with plant cell-wall degrading enzymes carry out process obtain micro-algae pre-treatment thing;

Step 2, described micro-algae pre-treatment thing is processed 10-30min under temperature is 80-120 DEG C and pressure is the condition of 0.05-0.25MPa obtain micro-algae secondary pre-treatment thing, described micro-algae secondary pre-treatment thing is used for extracting microalgae grease and microalgal polysaccharide.

2. the method simultaneously extracting microalgae grease and microalgal polysaccharide as claimed in claim 1, it is characterized in that, in described step 2, described micro-algae pre-treatment thing is processed 10-30min under temperature is 110-120 DEG C and pressure is the condition of 0.13-0.15MPa and obtain micro-algae pretreatment product.

3. the method simultaneously extracting microalgae grease and microalgal polysaccharide as claimed in claim 2, it is characterized in that, in described step 2, described micro-algae pre-treatment thing is processed 10-30min under temperature is 120 DEG C and pressure is the condition of 0.15MPa and obtain micro-algae pretreatment product.

4. the as claimed in claim 1 method simultaneously extracting microalgae grease and microalgal polysaccharide, is characterized in that, the mass percent that the addition of a kind of described plant cell-wall degrading enzymes of described step accounts for described micro-algae is 0.2-1%.

5. extract the method for microalgae grease and microalgal polysaccharide as claimed in claim 1, it is characterized in that, the pH value of in described step one, micro-algae plant cell-wall degrading enzymes being carried out combination treatment is 5.2-6.0, and temperature of reaction is 20-35 DEG C simultaneously, reaction 2-5h.

6. extract the method for microalgae grease and microalgal polysaccharide while according to any one of claim 1-5, it is characterized in that, described plant cell-wall degrading enzymes comprises cellulase and lywallzyme.

7. the method simultaneously extracting microalgae grease and microalgal polysaccharide as claimed in claim 6, is characterized in that, further comprising the steps of:

Step 3, in described micro-algae secondary pre-treatment thing, be added into organic extractant carry out extraction microalgae grease, isolate the microalgal polysaccharide liquid being rich in microalgal polysaccharide;

Step 4, described microalgal polysaccharide liquid filtered and removes microalgae cell residue;

Step 5, in described microalgal polysaccharide liquid, add trichloroacetic acid precipitation remove albumen and nucleic acid impurities and obtain secondary microalgal polysaccharide liquid;

Step 6, by centrifugal for described secondary microalgal polysaccharide liquid, collect supernatant, add wherein afterwards volume fraction be 80% ethanol synthesis to precipitation no longer increase, obtain micro-algae Crude polysaccharides.

8. the method simultaneously extracting microalgae grease and microalgal polysaccharide as claimed in claim 7, it is characterized in that, described organic extractant is chloroform or ether.

9. the method simultaneously extracting microalgae grease and microalgal polysaccharide as claimed in claim 7, it is characterized in that, described micro-algae comprises one or more in Dunaliella salina, micro-plan ball algae, chlorella or scenedesmus obliquus.

10. the method simultaneously extracting microalgae grease and microalgal polysaccharide as claimed in claim 7, it is characterized in that, described step 6, by centrifugal for described secondary microalgal polysaccharide liquid, collect supernatant, add wherein afterwards volume fraction be 100% ethanol synthesis to precipitation no longer increase, obtain micro-algae Crude polysaccharides.