355 results about "Chlorella sp." patented technology

The invention discloses a method for producing biological diesel oil by two steps of culture of chlorellas, namely, autotrophy and heterotrophy, which belongs to the renewable biological energy field. Concentrated autotrophic algae is put into a fermentation tank to perform heterotrophic growth from the processes of autotrophic culture, cell concentration and fermentation pollution controlling of the chlorellas, to ensure the chlorellas to be synthesized into neutral fat. Effective feeding strategy is established to ensure the fat to be synthesized into optimal after the optimization of the fermentation conditions and the process control. The biomass can reach 108g.L-1, and the grease content can reach 52 percent of cell dry weight. After the culturing is finished, biological diesel oil can be prepared after extracting algal oil and transesterification reaction. The cell concentration technology adopted by the invention can effectively avoid the problem of light restriction during the high density culture process Not only is the carbon dioxide emission reduced, but also the organic carbon source consumption is reduced, thus the preparation cost of the biological diesel oil material is saved. The whole technical line is environmental friendly, high efficient, and can meet the industrial application requirements of the microalgae biological diesel oil.

The invention belongs to the technical field of microalga biology, and particularly relates to a microalga strain with high CO2 tolerance and high fixation rate and a breeding method thereof. The microalga is named Chlorella sp.Y-1, and is collected into Common Microorganism Center of China General Microbiological Culture Collection Committee; and collection number is CGMCC No.5429. The invention has the following characteristics: the initial strain is separated from natural environment; after high-CO2-concentration enrichment culture, gene cloning, induced mutation breeding and other operations, the carbon content of the target strain is increased to 56.981%, the optimal fixation concentration is up to 20% (v / v), the fixation rate is up to 5.762g / (L.d), and the maximum tolerance concentration is 100% (v / v); and the target strain has high adaptability to a series of physical and chemical culture conditions, has high culture transfer stability, and high better overall properties than the like research findings at present. The invention aims to solve the bottleneck problem in high concentration CO2 biological fixation technology, cultures an efficient organism capable of efficiently fixing high concentration CO2, implements effective fixation of CO2 in high concentration flue gas and other complex environments, and meanwhile, generates beneficial biological substances.

The invention discloses a small ball algae cultivation method with high density and high quality, which comprises the following phases: high-density heterotrophy cultivation, high-density algae liquid dilution and photo-autotroph cultivation. The invention makes the small ball algae reach high-density level within shorter cultivation period, which improves the small ball algae quality.

The invention discloses a Chlorella strain and an application thereof. The Chlorella strain provided by the invention is Chlorella sp. YL-2 of which collection number is CGMCC No.4305. The Chlorella sp. YL-2 can well grow in sewage, and can efficiently remove nitrogen and phosphorus in sewage. The Chlorella sp. YL-2 is rich in oil and fat, and can be used for preparing biodiesel. Therefore, the Chlorella sp. YL-2 has wide application prospects in culture using sewage and biodiesel conversion system.

The invention discloses a milk beverage formula containing algae. The milk beverage contains one or more of chlorella, spirulina and haematococcaceae, also can be one or more of the algae extracts, wherein adding amount is 0.1%-4%; the algae milk beverage is milk-containing beverage which is prepared by taking milk or a milk product as a material, adding water and one or more of chlorella, spirulina and haematococcaceae, and modulating one or more of sugar and (or) a sweetening agent, an acid agent (or not added with the acid agent), fruit juice, planting fat end, instant tea powder or tea extracts, coffee, plant extract (liquid), and the like; according to the algae milk beverage, the chlorella, spirulina and haematococcaceae are added into the sugar and (or) the sweetening agent, the acid agent, the milk material, the plant extract (liquid), a feed additive, and the like by a burdening step, and prepared into a finished product by processes of dissolving, mixing, cooling, adding acid (or not adding acid), homogenizing, filling, sterilizing, cooling, labeling, inspecting, and the like, and also can be prepared into a finished product by adopting a sterile packaging way, directly sterilizing after homogenizing, thermally filling, cooling, labeling, inspecting, and the like. The product prepared by the technology disclosed by the invention has characteristics of being mellow in mouthfeel, rich in nutrition, healthy and green.

The present invention relates to algal species and compositions, methods for identifying algae that produce high lipid content, possess tolerance to high CO2, and / or can grow in wastewater,, and methods for using such algae for lipid production, wastewater remediation, waste gas remediation, and / or biomass production.

The invention provides a preparation method for a chlorella polypeptide microcapsule. The method comprises the following steps: extracting chlorella protein by using a low temperature ultrahigh pressure continuous flow cell crusher; hydrolyzing the chlorella protein with papain; filtering the hydrolyzed chlorella protein with an ultrafiltration centrifuge tube; then carrying out separation and purification by using ion exchange chromatography DEAE-52 and gel chromatography dextrangel G-25 columns; and finally utilizing complex coacervation to prepare the chlorella polypeptide microcapsule. The chlorella polypeptide microcapsule prepared in the invention has antitumor activity, e.g., the chlorella polypeptide microcapsule has inhibitory effects on in vitro growth of human hepatoma carcinoma cells HepG2 and the inhibition rate of the chlorella polypeptide microcapsule reaches 38% when concentration is 400 mu g / mL. Therefore, the chlorella polypeptide microcapsule prepared in the invention is beneficial for development and utilization of antitumor health food and medicinal products.

The invention relates to a Chlorella microbiological fuel cell reactor, which belongs to the technical field of biological treatment, reuse and resource recovery of sewage. The reactor mainly comprises an anode chamber, a cathode chamber, leads, a load, a proton exchange membrane and the like, wherein, the anode chamber is separated from the cathode chamber through the proton exchange membrane, an anode is provided in the anode chamber, and a cathode is provided in the cathode chamber. According to the invention, the reactor is started, and anode flora in high-concentration organic waste water is domesticated and treated; the high-concentration organic waste water is allowed to enter into the anode chamber for anaerobic treatment by anode bacteria for 10 days at room temperature, anode effluent is allowed to enter into the cathode chamber for in-depth denitrification and dephosphorization and further absorption of organic matters by cathode Chlorella, and final effluent reaches the third level discharge standard of urban sewage treatment; the cathode Chlorella is collected, and crude grease of biodiesel is extracted. The invention enables low cost treatment of high-concentration organic waste water to be realized and allows clean effluent to be obtained and electric energy and biodiesel to be recovered, thereby genuinely realizing resource utilization of the waste.

The invention discloses a method for extracting lipid from Chlorella sorokiniana CS-01 (CCTCC M209220), namely an ultrasonic-assisted chloroform / methanol extraction method. The method mainly comprises the following steps of: collecting algae, drying, extracting by using chloroform / methanol, performing ultrasonic crushing, washing, and drying. Through the certification, compared with a Soxhlet extraction method, an acid heat extraction method, and a chloroform / methanol extraction method, the method has the advantages that: the extraction ratio of the lipid is improved by 1.4, 1.7 and 0.5 timesrespectively; meanwhile, a lipid extraction phase is positioned under a cell debris solid phase, so the method is favorable for the subsequent direct separation of the lipid, and meets the requirements of mass industrialized production.

The invention discloses chlorella sorokiniana, named chlorella sorokiniana BL-ch1 which has been collected, on November 8, 2016, in the China Center for Type Culture Collection at Luojia Hill, Wuchang, Wuhan. The collection number is: CCTCC M 2016626. A culture method of the chlorella sorokiniana comprises: inoculating a strain to a culture medium, wherein the inoculation quantity is 5-15%, the culture volume is 400-800mL / L, the initial pH is 6.0-8.0, and the culture temperature is 28-33 DEG C. The screened chlorella sorokiniana is high in protein content, and high in degradation rate for total nitrogen, total phosphorus and ammonia nitrogen, and can be used for the fields of protein production, feed preparation, sewage treatment and the like.

The invention provides a low-temperature ultrahigh-pressure preparation method of chlorella protein, which comprises: mixing chlorella power and pure water in a mass ratio of 1:10 to 1:30, and stirring for 30 to 90 minutes to obtain mixed solution; extracting chlorella protein from the mixed solution at 4 to 8 DEG C and under 100 to 200 MPa to obtain coarse extract solution; and subjecting the coarse extract solution to centrifugal separation, concentrating and drying supernate, and obtaining chlorella protein powder. In the invention, the application of the ultrahigh pressure makes the walls of the chlorella broken completely, the need of heating is obviated, and low-temperature operation is favorable for protecting the bioactivity of protein; the need of adding enzyme is obviated, and cost is expected to be reduced; and acid and alkali are not added, so pollution of acid and alkali is avoided. The method is simple in preparation process, quick and suitable for large-batch production, and is a safe and high-efficiency method for industrial preparation of chlorella protein.

The invention relates to an algae organism culture technology, in particular to a method for quickly growing chlorella and accumulating a large amount of biological grease through mixotrophic culture. In the method, two-stage culture is adopted, namely at the first stage, high biomass is obtained through the autotrophic aerated culture of the chlorella, and at the second stage, an aerated heterotrophic culture mode of adding organic matters is adopted, the single nutrition mode of the chlorella is changed, and the grease is quickly accumulated on the basis of a large amount of biomass; meanwhile, a novel air sterilization method is adopted to effectively solve the problem of bacterial contamination of culture solution, and culture cost is reduced because a filter membrane is not needed; and algae powder grease is extracted by an alkali-catalyzed anhydrous diethyl ether-petroleum ether extraction method. The method has the advantages that: the whole process is easy to operate, experiment cost and production cost are low, the culture period is short, the grease accumulation concentration of microalgae can be quickly improved, and the extracted grease has high content and purity and is not required to be decolorized; and the method is suitable for preparing microalgae grease in a laboratory or in the industry, and has a good application prospect.

The invention provides an antioxidative peptide and a preparation method thereof. The method is used for obtaining the specific antioxidative peptide from chlorella protein as the raw material by virtue of enzymolysis of an acid proteinase, separation and purification; the amino acid complete sequence of the specific antioxidative peptide is aetiglap. The shortcomings of a natural antioxidant are overcome and the worry of the public on an artificially synthetic antioxidant is eliminated, and a foundation is laid for developing the antioxidative peptide based on food sources and exploring the wide application of the antioxidative peptide in foods and medicines.

The present disclosure concerns methods and compositions to inhibit insects from biting a subject. In preferred embodiments, the compositions may be administered orally, for example using a spray bottle to deliver to the mouth. In certain embodiments, the compositions and methods are effective to reduce swelling, itching, redness and / or inflammation of the local area of an insect bite. The compositions may include one or more herbs selected from the group consisting of rice bran, peppermint, barley grass, lobelia; chlorella, watercress, alfalfa and parsley and one or more vitamins selected from the group consisting of thiamin (B-1), riboflavin (B-2), niacin (B-3), pantothenic acid (B-5), pyridoxine (B-6), folic acid (B-9), cyanocobalamin (B-12), choline, inositol, d-biotin, para-aminobenzoic acid, and lecithin. Administration of effective amounts of the compositions is sufficient to inhibit insects from biting and / or treat insect affected areas of a subject.

The invention discloses a method for hybridizing female verasper variegatus and male verasper moseri for breeding and fry cultivating, comprising the steps of selection of parents, parent fish cultivation and reproduction control, artificial insemination and incubation and cultivation of fish larvae and juvenile fish, wherein female verasper variegatus older than 3 years is selected to be used as a female parent, and male verasper moseri older than 2 years is selected to be used as a male parent; and the sexual maturity synchronization of the female parent fish and the male parent fish is promoted by means of temperature control, light control and nutrition enhancement. With respect to the artificial insemination, the insemination rate reaches 50%; the water temperature for incubation is (10+ / -0.5) DEG C, fish larvae can be incubated from inseminated eggs after 160 hours, and the incubation rate reaches more than 50%; and with respect to a feed series, L-type brachionus plicatilis and chlorella sp., artemia nauplii, and compound feed are respectively applied in different stages. The fish larvae (1-35 days in age) in an early stage are cultivated in a small water body (3m<3>) at the water temperature of (10+ / -0.5) DEG C; after 3 days, the temperature is raised by 0.5 DEG C every 2 days and is kept unchanged after reaching (15+ / -0.5) DEG C; and the fish larvae in a later stage are cultivated in a water body (30m<3>). After cultivating for 80 days, the survival rate of the fish larvae growing into the juvenile fish of 30mm in average is 20%. The method disclosed by the invention can be used for cultivating novel breeds and realizing scale breed reproduction.

The invention provides an acne-removing composition, and a preparation method and application thereof. The acne-removing composition comprises the following components in percentage by weight: 10 to 50 percent of radish root fermented product filtrate, 10 to 50 percent of a soybean fermented product extract, 15 to 35 percent of a chlorella fermented product and 5 to 25 percent of a rice bran fermented product. The acne-removing composition provided by the invention can effectively exert the synergistic effect of plant fermented products according to compounding of the four fermented products so as to effectively exert bioactivity. The acne-removing composition has a good acne-removing effect and is safe and non-irritant to skin.

The invention provides a method for improving the biomass of chlorella in swine wastewater, belonging to the field of microbe application. Chlorella assigned with the accession number of CGMCC NO.9225 and paenibacillus elgii assigned with the accession number of CGMCC NO.7724 are co-cultured in the swine wastewater, the result shows that paenibacillus elgii can obviously improve the biomass of chlorella in the swine wastewater, and the promotion effect achieves 1.6 times. With the adoption of the method, the treatment problem of the swine wastewater is solved, and the environment pollution is reduced; due to the addition of paenibacillus elgii, the water body microenvironment in the swine wastewater is improved, the biomass of chlorella is obviously improved, further, the production cost of microalgae biodiesel is reduced, thus good economic benefit is obtained, and therefore, the method has a good market application prospect.

The invention discloses a monitoring and identifying evaluation method for group biotoxicity in printing and dyeing wastewater and belongs to the field of biotoxicity identification. The method comprises the following steps: screening photogenic bacteria, zebrafish larvae, zebrafish embryos and chlorella as test organisms; and performing risk and toxicity reduction evaluation on the printing and dyeing wastewater by adopting group biotoxicity tests and combining with a toxicity evaluation method, and constructing a toxicity identification evaluation system by combining with a TIE technology according to the wastewater contamination characteristics and results. According to the method disclosed by the invention, the group biotoxicity tests comprising three trophic levels such as decomposer,producer and consumer are performed for characterizing toxicities of the printing and dyeing wastewater, and the problem that a single biotoxicity test does not have representativeness is solved. Themethod has the advantages of being comprehensive, simple, high-efficiency, capable of controlling from the source, high in safety and the like, can be widely applied to researching and evaluating influences of toxic pollutants on the ecological environment, and provides a certain basis for ecological risk assessment.

The invention relates to Chlorella, particularly a Chlorella strain for synchronously treating municipal sewage and implementing grease accumulation. The invention aims to solve the problems of poor stress tolerance, low alga cell grease content, poor decontamination capacity, difficulty in degrading carbon source substances in sewage, and requirement of adding exogenous nutrient substances for growth in sewage in the coupling process of a microalga biodiesel production system and a municipal sewage treatment system. The Chlorella sp. PF2 is collected at China General Microbiological Culture Collection Center, the collection address is Beichenxi Road No.1 Yard 3, Chaoyang District, Beijing City, the collection date is July 30th, 2013, and the collection number is CGMCC No.8014. The Chlorella sp. PF2 has strong anti-pollution capacity, and can grow and reproduce in common nonsterile municipal sewage by using carbon, nitrogen, phosphorus and other pollutants as nutrient substances while accumulating grease.

The invention provides a mutant chlorella strain capable of realizing high yield of zeaxanthine and other carotenoids essential to the human body, and a culturing method thereof. The culturing method comprises the following steps: subjecting Chlorella zofingiensis ATCC 30412 to nitrosoguanidine mutagenesis; then coating a Kuhl solid medium containing DPA with treated chlorella cells for culture; selecting a single chlorella colony from the Kuhl solid medium and culturing the single chlorella colony on a Kuhl liquid medium; adding glucose in the middle and later periods of logarithm for induction of carotenoid synthesis; and detecting the variety changes and content of carotenoids in the obtained chlorella body so as to obtain the strain which can realize high yield of zeaxanthine, xanthophyll and beta-carotene and is named as CZ-ZEA1. Under the induction condition that the concentration of glucose is 30 g / L, the biomass of the CZ-ZEA1 is 12.95 g / L, and the contents of zeaxanthine, xanthophyll and beta-carotene reach 2.176 mg / g, 1.10 mg / g and 1.211 mg / g, respecitively. The mutant chlorella strain is an edible alga species and contains high-content optimally-proportioned carotenoids essential to the human body, especially zeaxanthine rare in nature; so the mutant chlorella strain is an ideal new-resource functional foodstuff for preventing deterioration and lesion of the eyes of middle aged and old people and has good development and application prospects.

The invention relates to the technical field of biomass energy, and particularly relates to an imnetic chlorella strain Chlorella sorokiniana HN01 and application thereof to high density fermentation for production of chlorella nutritional health products. The imnetic chlorella strain Chlorella sorokiniana HN01 provided by the invention has a preservation number of CCTCC M2013608, can realize high-density high-quality fermentation in a photoheterotrophy-chemoheterotrophy light switching cultivation mode. Chlorella fermented algae powder has biomass of 6. 2g / L, protein content of 39%, and content of essential fatty acid including linoleic acid and linolenic accounting for more than 20% of total fatty acid content. The invention provides a good algae strain and key fermentation technology for wide application of chlorella in the industries of food, nutritional health products, cosmetics medicine and chemical engineering, and can ensure high-density high-quality fermentation of chlorella and enhance the international competitiveness of China's chlorella industry.

The invention discloses a culture method capable of reducing chlorella adherence.The culture method includes preparing a BG-11 culture solution, and adding a 10-300 ppm emulsifying agent into the BG-11 culture solution to obtain a culture solution capable of reducing chlorella adherence.The culture method capable of reducing chlorella adherence means that the culture solution capable of reducing chlorella adherence is used for culturing chlorella.When cultured chlorella cells reach a stable phase, dry cell weight as high as 875-956 mg can be obtained from every L of culture solution and is increased by 40-66% than a BG-11 chlorella culture solution without the emulsifying agent.The culture solution capable of reducing chlorella adherence has no adverse effect on growth of the chlorella, and accordingly the cultured chlorella is safe and free of toxicity and is particularly suitable as raw materials of health products, feed, food additives, fine chemical products and medical preparations.

The invention discloses a green alga and viable bacterium compound, a method for preparing the same and application of the green alga and viable bacterium compound. The green alga and viable bacteriumcompound comprises, by weight, 40-60 parts of green algae and 10-20 parts of viable bacteria. The green algae are chlorella, and the viable bacteria are photosynthetic bacteria and bacillus polymyxa.The green alga and viable bacterium compound, the method and the application have the advantages that the green alga and viable bacterium compound can be used in the agricultural field; the bacteriaand the algae are complementary with one another, and accordingly the green alga and viable bacterium compound is environmentally friendly; effects of promoting growth of crops, improving the diseaseresistance of the crops, increasing the yield of the crops and improving the quality of the crops can be realized; the green alga and viable bacterium compound can be used as a foliar fertilizer, accordingly, the photosynthetic rates of the crops can be increased by 2-3 times, nitrogen sources and carbon dioxide in air can be sufficiently utilized, energy can be saved, and environments can be protected; effects of remedying soil further can be realized by the green alga and viable bacterium compound, and effects of immobilizing heavy metal, degrading harmful substances such as polycyclic aromatic hydrocarbons, reducing the salt concentration and improving the water retention and fertilizer conservation capacity of the soil can be realized by the green alga and viable bacterium compound.

The invention relates to the technical field of biomass energy, and in particular to a freshwater chlorella strain (i) Chlorella sorokiniana ( / i) GS03 and application thereof to industrial flue gas CO2 fixation and production of microalgae biodiesel. The chlorella strain (i) C.sorokiniana ( / i) GS03 provided by the invention has a preservation number of CCTCC M2013607, and higher CO2 tolerance, higher fixation efficiency of high-concentration carbon dioxide and higher biomass yield and oil yield compared with the reported microalgae strains. Therefore, the invention can greatly reduce microalgal oil production cost, and provides a good production strain for algae for efficient fixation of CO2 in typical industrial flue gas environment and biodiesel production from microalgae oil, and shows great application prospect in the field of biomass energy.

Compositions and methods for indirectly reducing incidence of fungal pathogen infection in a plant are disclosed, wherein the fungal pathogen may be Botrytis, Macrophomina, Rhizoctonia, Sclerotinia, or Verticillium. The compositions comprise pasteurized microalgae cells in an amount effective to reduce incidence of the fungal pathogen in a plant compared to a substantially identical population of untreated plants. The composition treatment can include at least one microalgae such as Chlorella, Aurantiochytrium acetophilum HS399, Galdieria, Scenedesmus, Haematococcus, Isochrysis, Spirulina or any combination thereof. Where the composition comprises a combination of a first microalgae and a second microalgae, the composition may consist of a ratio of 25:75, 50:50: or 75:25.

The invention provides a preparation method for chlorella antitumor polypeptide. The preparation method is characterized in that chlorella protein is extracted by using a low temperature ultrahigh pressure continuous flow cell crusher, then is hydrolyzed by trypsin and finally filtered with an ultrafiltration centrifuge tube so as to obtain chlorella polypeptide with a molecular weight in ranges of 0 to 3 KD, 3 to 5 KD, 5 to 10 KD and more than 10 KD. The chlorella polypeptide prepared in the invention has antitumor activity, e.g., the chlorella polypeptide has inhibitory effects on in vitro growth of human hepatoma carcinoma cells HepG2 and inhibition rates of chlorella polypeptide with a concentration of 1 mg / mL and in ranges of 0 to 3 KD, 3 to 5 KD and 5 to 10 KD on in vitro growth of hepatoma carcinoma cells (HepG-2) respectively reach 7%, 14% and 10%. Therefore, the chlorella antitumor polypeptide prepared in the invention is beneficial for development and utilization of antitumor health food and medicinal products.

The invention discloses a nano light carbon agent and preparation method thereof. The nano light carbon agent is prepared from the following components in a certain proportion: carbon nano tube, titanium dioxide nano tube, chlorella, porphyridium, glutamine, alanine, histidine, NaHCO3 (sodium bicarbonate), KNO3 (potassium nitrate), KN2PO4 (monopotassium phosphate) and distilled water; the preparation method comprises the following steps: (1) respectively weighing the raw materials for later use; (2) respectively weighing the raw materials in the step (1) according to weight percentage, uniformly mixing the carbon nano tube, titanium dioxide nano tube, chlorella, porphyridium, glutamine,alanine, histidine, NaHCO3, KNO3, KN2PO4 and distilled water, regulating pH value by using sodium hydroxide, putting in a reaction vessel, adequately stirring, and reacting for 8-12 hours to obtain the nano light carbon agent. The nano light carbon agent is reasonable in formula, convenient to use, simple to operate and high in nutrition use rate, is ecological and environment-friendly, has no environment pollution and can be conveniently popularized and applied; the yield of crops and the quality of fruits are improved to the greatest extent; and the preparation method is easily implemented.

The invention relates to a high-fat Chlorella culture solution for promoting rapid growth and a preparation method thereof, belonging to the field of a biotechnology. The culture solution comprises the following components in percent by weight: 1-8% of bamboo vinegar, 4-15% of macronutrient, 0.2-0.5% of micronutrient, 0-1.5% of soil extract and 78-94% of water, wherein the macronutrient is one ofsodium nitrate, dipotassium hydrogen phosphate, potassium nitrate, magnesium sulfate, calcium chloride, potassium dihydrogen phosphate and sodium chloride or a mixture thereof, and the micronutrient is one of ferric chloride, boric acid, copper sulfate, manganese sulfate, zinc sulfate and ammonium molybdate or mixture thereof. Since the bamboo vinegar serving as a synergic ingredient is added into the culture solution, the content of the fat generated during the process of the carbon dioxide immobilization using algae is increased. The high-fat Chlorella culture solution is simple in preparation method, low in production cost, and convenient in operation, and can be used for greatly increasing the content of the fat in Chlorella; and under the same conditions, the purity of the cultured algae is very high, and the culture cost for large-scale exploitation and utilization of the Chlorella is greatly reduced.

The invention discloses a composite for improving the immunity and application. The composite is prepared from, by weight, 10-30 parts of agaricus blazei murill extract, 10-30 parts of grifola frondosa extract, 10-30 parts of chlorella pyrenoidosa, 5-15 parts of cordyceps militaris extract, 1-10 parts of ginseng extract, 10-20 parts of sea buokthom powder, 1-10 parts of yeast beta-glucose, 1-10 parts of erythritol and 1-5 parts of nutritional yeast powder. It is proved through animal tests that all the raw materials in the composite have an effect on improving the immunity synergistically.

The invention discloses a chlorella exopolysaccharide with antioxidant activity. The chlorella exopolysaccharide disclosed by the invention is secreted by chlorella having undergone liquid culture under the conditions of salt stress and a light-dark alternating mode and is eventually prepared through separation and purification. The chlorella exopolysaccharide has an average relative molecular weight of 131.79 kDa, and is mainly composed of, by mol, 19.81% of xylose, 79.93% of mannose and 0.25% of ribose. According to the invention, extracellularly-secreted polysaccharide is separated from a chlorella fermentation medium environment for the first time, and the obtained chlorella exopolysaccharide has an obvious dose effect on removal of DPPH free radicals, superoxide anions, hydroxyl radicals and ABTS radicals. Through the utilization of exopolysaccharides secreted to a culture medium in a microalga culture process, can the high additional value of the byproducts can be fully excavated, a new thought can be provided for lowering the production cost of microalgal oil for biodiesel preparation, and obvious social and economic benefits are obtained.