JP2018102158A - Methods for collecting halophilic microalgae - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide methods for efficiently collecting halophilic microalgae utilizing precipitation by salting out.SOLUTION: The method for collecting halophilic microalgae of the invention collects the alga body of an alga belonging to halophilic microalgae utilizing precipitation due to protein denaturation, the method comprising the steps of: culturing a halophilic microalga in a culture fluid containing a salt; adding to the culture fluid an organic solution containing a protein followed by mixing and standing it to separate the mixed solution into a precipitate and a supernatant; and recovering the alga body in the precipitate.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for collecting microalgae, and more particularly, to a method for collecting halophilic microalgae.

  Conventionally, as a technique for recovering microalgae such as Euglena and Botryococcus, for example, JP 2012-179578 A (Patent Document 1) and JP 2014-168409 A (Patent Document 2) are known. Yes.

  In patent document 1, the method of isolate | separating and collect | recovering the precipitation of a micro algae from the raw | natural water containing a micro algae using a coagulant precipitation agent is disclosed. More specifically, in the method for separating and recovering microalgae described in Patent Document 1, the salt concentration of raw water is adjusted so as to have a surface zeta potential at which microalgae tend to aggregate, and inorganic agglomeration is performed on the raw water containing microalgae. An aggregating reaction is performed by adding an agent, and the agglomerated flocs generated by the aggregating reaction are separated into solid and liquid.

  Patent Document 2 discloses a method for attracting and concentrating and recovering microalgae with light. More specifically, in the method of concentrating the microalgae culture solution described in Patent Document 2, the microalgae culture solution containing microalgae is irradiated with light having a wavelength that attracts microalgae, The portion where the concentration of microalgae is increased by light irradiation is taken out.

  In the method for separating and recovering microalgae described in Patent Document 1, since the precipitate is separated and recovered using an aggregating precipitant, the problem of the cost of the drug to be added, the problem of separation of the drug after separating and recovering the precipitate, etc. was there.

  Further, the method for concentrating the microalgae culture solution described in Patent Document 2 has a problem that the microalgae recovery efficiency is insufficient, although it can be somewhat concentrated.

  Moreover, as a technique for recovering microalgae by a physical method, for example, Japanese Patent Application Laid-Open No. 2013-85488 (Patent Document 3), Japanese Patent Application Laid-Open No. 2015-57990 (Patent Document 4) and Japanese Patent Application Laid-Open No. 2016-082910 ( Patent document 5) is known.

  In patent document 3, the apparatus which floats and collect | recovers micro algae by bubbling is disclosed. More specifically, in the microalgae culture recovery apparatus described in Patent Document 3, the microalgae are cultured and grown in a culture solution filled with a predetermined amount of liquid containing organic matter. Then, pressurized air is supplied to an aeration nozzle disposed in the culture solution, and aeration for generating fine bubbles is performed to generate circulatory convection and to float and collect microalgae.

  Patent Document 4 discloses a multistage culture method in which a microalgae biofilm is formed, and the floated and precipitated materials are pressed against a plate and collected. More specifically, in the multi-stage culture method for microalgae described in Patent Document 4, at least two incubators are arranged in a stacked manner, the microalgae are cultured in the medium in each incubator, and the liquid level of the medium A biofilm is formed on the surface, and microalgae are obtained and collected from the biofilm floating on the liquid surface.

  Moreover, in patent document 5, the culture system which collects the algae contained in the upper layer of a liquid by scraping the upper layer of the liquid accommodated in the culture tank in a scraping part is collect | recovered. More specifically, in the culture system described in Patent Document 5, the upper layer of the culture tank in which the algae is cultured in the culture solution is raked up by the scraping section to overflow from the overflow section of the culture tank. The liquid overflowed from the overflow section is retained and stored in the retention section, and the algae retained in the retention section is taken out by the extraction section.

JP 2012-179578 A JP 2014-168409 A JP 2013-85488 A JP 2015-57990 A Japanese Patent Application Laid-Open No. 2016-082910

  As described above, Patent Document 1 and Patent Document 2 have problems such as the cost of the drug used and problems in the recovery efficiency of microalgae.

  Moreover, in the said patent document 3-patent document 5, as mentioned above, the micro algae were collect | recovered with the physical method. Even by these physical methods, it is possible to recover microalgae to some extent.

  By the way, for example, Donariella is known as a microalga belonging to halophilic microalgae. Donariella is excellent in an antioxidant action and an anti-inflammatory action that assists cell regeneration, and is used, for example, as a food or as an active ingredient in cosmetics, drugs, and the like. In recent years, Donariella is expected as a new biomass resource because it accumulates a lot of valuable materials in the body.

  In addition, Donariella is characterized by its extremely high growth rate and high salt tolerance, so that it can suppress contamination of other miscellaneous microorganisms even when cultured in an open outdoor environment.

  However, since Donariella has no cell wall, there is a problem that the cells are fragile and are difficult to recover by the physical method described above.

  Donariella is halophilic and breeds in places with high salinity. From the viewpoint of preventing contamination, Donariella is cultured at a salt concentration about 4 to 5 times that of seawater. Therefore, in order to reuse the salt, it is necessary to separate and recover the salt together with the alga body from the culture solution. It was.

  For these reasons, when recovering halophilic microalgae such as Donariella, conventional methods have not been able to cope with problems such as cost, recovery efficiency, and work efficiency. Therefore, development of a recovery method capable of efficiently recovering halophilic microalgae such as Donariella is desired instead of a conventional physical recovery method.

  Therefore, the inventors use salting out by alcohol precipitation in order to efficiently recover halophilic microalgae in a simple and mild condition (quiet state), instead of the conventional physical recovery method. Then, the method of collect | recovering halophilic microalgae, such as Donariella, was considered.

  More specifically, pure water was added to commercially available artificial seawater (powder) to prepare a culture solution having a salt concentration of about 15% by weight. Donariella was cultured in a culture solution for 14 days, and the culture solution was dispensed into tubes. Next, various alcohols were added to each tube, mixed and allowed to stand for 10 minutes, and the mixed solution was separated into a supernatant and a precipitate. The supernatant and the precipitate were each observed with an optical microscope.

  In the above test examples, no drug other than alcohol is added, and no centrifugation is performed. In addition, when various alcohols were added, they were mixed under mild conditions without strong stirring. And the time required for precipitation was substantially 1-2 minutes. The observation results of salting out by alcohol precipitation are shown in FIGS.

  In salting out by alcohol precipitation, salt ions and alcohol ions are ionically bonded due to decomposition of the salt. Then, the algae are precipitated by being pulled electrically by the salt crystals.

  As shown in FIG. 1 (a), a culture solution (Cul.) Was used as a control. Further, ethanol (EtOH) and 2-propanol (2-propanol) were used as various alcohols.

  As shown in FIGS. 1B and 1C, in the control, only Donariella alga bodies were observed in the culture solution.

  As shown in FIGS. 1D and 1E, in the salting out with ethanol, the mixed solution was separated into a supernatant and a precipitate. The supernatant contained only the culture solution (liquid), and Donariella and salinity were not observed. In the precipitate, crystals of Donariella algae and salts were observed by ethanol precipitation.

  As shown in FIG. 1B, in the salting out with 2-propanol, the mixed solution was separated into a supernatant and a precipitate. However, the amount of precipitate was significantly less than salting out with ethanol.

  As a result of observation with an optical microscope, the collected Donariella alga bodies (cells) were not broken, and when ethanol was added, the Donaliella alga bodies (cells) and salts necessary for culture could be recovered sufficiently. I found out.

  However, in salting out by alcohol precipitation, since ethanol (liquid) is added, the liquid content increases, and since the liquid content does not contain salt, the salinity cannot be reused. As a result, there has been a problem that the amount of drainage (supernatant) is increased.

  In salting out with 2-propanol, the increase in 2-propanol (liquid) can be suppressed to some extent. However, there are few precipitates, and the salt required for culture | cultivation cannot fully be collect | recovered with the algal body (cell) of Donariella.

  Accordingly, the inventors have conducted extensive studies in view of such a situation, and as a result, have a salting out with materials other than alcohol, and in particular, an efficient method for recovering halophilic microalgae using precipitation due to protein denaturation. I got new knowledge.

  An object of the present invention is to provide a method for recovering halophilic microalgae that can efficiently separate and recover halophilic microalgae using precipitation due to protein denaturation.

  The method for recovering halophilic microalgae of the present invention is a method for recovering halophilic microalgae that obtains algal bodies of algae belonging to halophilic microalgae using precipitation due to protein denaturation, A step of culturing halophilic microalgae in a culture solution containing salt, and an organic solution containing protein is added to the culture solution, mixed and allowed to stand, and the mixed solution is made into a precipitate and a supernatant. And a step of recovering the algal bodies contained in the precipitate.

  According to the above method for recovering halophilic microalgae, the step of culturing the salty microalgae in a culture solution containing salt, and the organic solution containing protein is added to the culture solution, mixed and allowed to stand. And the step of separating the mixed solution into a precipitate and a supernatant and the step of recovering the alga bodies contained in the precipitate, so that the protein component in the organic solution is denatured by the presence of a salt, As the molecular structure of the protein changes, halophilic microalgae precipitate with the protein components. Further, the salt content in the culture solution is contained in the supernatant.

  As a result, halophilic microalgae are present in the precipitate together with protein components, and the salt content is contained in the supernatant. It can be separated and recovered efficiently. Moreover, since there is little increment of the liquid amount of the organic substance solution to add, the burden of the processing amount of a supernatant liquid (drainage) is suppressed.

  In one aspect of the present invention, the halophilic microalgae are Donariella spp., Nostoc spp., Symploca spp., Prochloron spp., Skeletonema spp., Thalassosiera spp., Chaetoceros spp. It is preferably a microalga selected from the group consisting of Monochrysis genus, Chlorella genus, Spirulina genus, Synechococcus genus, Phaeodactylum genus, and Bangia genus.

  According to the method for recovering halophilic microalgae, the halophilic microalgae are Donariella spp., Nostoc spp., Symploca spp, Prochloron spp, Skeletonema spp, Thalassiosira spp, Chaetoceros spp , A microalga selected from the group consisting of Tetraselmis genus, Monochrysis genus, Chlorella genus, Spirulina genus, Synechococcus genus, Phaeodactylum genus, Bangia genus, The various halophilic microalgae can be efficiently separated and recovered using precipitation due to protein denaturation.

  As another aspect of the present invention, the culture solution preferably has a salt concentration of 3.5% to 20%. According to the method for recovering halophilic microalgae, when the culture solution has a salt concentration of 3.5% to 20%, the halophilic microalgae is more efficiently utilized by using precipitation due to protein denaturation. Can be separated and recovered.

  As still another embodiment of the present invention, the temperature of the mixed solution is preferably in the range of 10 ° C to 30 ° C. According to the method for recovering halophilic microalgae, if the temperature of the mixed solution is in the range of 10 ° C. to 30 ° C., the halophilic microalgae can be more efficiently utilized by utilizing precipitation due to protein denaturation. Can be separated and recovered.

As another embodiment of the present invention, the algal body concentration in the culture solution is preferably 10 ⁶ cells / ml. According to the method for recovering halophilic microalgae, if the algal body concentration in the culture solution is 10 ⁶ cells / ml, a precipitate can be sufficiently generated using precipitation due to protein denaturation. And halophilic microalgae can be separated and recovered even more efficiently.

  As still another embodiment of the present invention, it is preferable to add an organic substance solution containing 5 to 10% by weight of the protein to the culture solution. According to the method for recovering halophilic microalgae, when an organic substance solution containing 5 to 10% by weight of protein is added to the culture solution, halophilic microalgae are utilized by utilizing precipitation due to protein denaturation. Can be separated and recovered even more efficiently.

  As yet another aspect of the present invention, it is preferable that the method further includes a step of mixing and homogenizing with a buffer flow after the addition of the organic solution containing the protein to the culture solution. According to the method for recovering halophilic microalgae, the method further includes a step of mixing and homogenizing with a buffer flow after the addition of the organic solution containing the protein to the culture solution. The organic matter solution containing can be further uniformly mixed, and halophilic microalgae can be separated and recovered more efficiently by utilizing precipitation due to protein denaturation.

  As still another aspect of the present invention, it is preferable that the method further includes a step of recovering the salt contained in the supernatant. According to the above method for recovering halophilic microalgae, the method further includes the step of recovering the salt contained in the supernatant, and therefore, as a salt necessary for culturing the halophilic microalgae in the culture solution, The salt contained in the liquid can be recovered and reused.

  As still another aspect of the present invention, it is preferable that the method further includes a step of returning the recovered salt to the culture broth and reusing it. According to the above method for recovering halophilic microalgae, the method further includes a step of returning the recovered salt back to the culture solution and reusing it, and is necessary for culturing the halophilic microalgae in the culture solution. As a salinity, the recovered salt can be returned to the culture medium again and reused more efficiently.

  As still another embodiment of the present invention, the organic solution containing the protein preferably contains skim milk, milk, soy milk or egg. According to the method for recovering halophilic microalgae, the organic substance solution containing protein contains skim milk (fat dry milk), milk, soy milk, or egg, so that the protein component is inexpensive and easy to procure, for example, for food and drink If it is an organic solution containing a protein component as used, halophilic microalgae can be more efficiently separated and recovered by utilizing precipitation due to protein denaturation.

  As described above, according to the method for recovering halophilic microalgae of the present invention, it is possible to efficiently separate and recover halophilic microalgae using precipitation due to protein denaturation. Can have an effect.

It is a graph which shows the observation result of salting out by alcohol about the collection method of halophilic microalgae. It is a figure which shows the observation result of the salting out by various materials about the collection method of the halophilic microalgae concerning one Embodiment of this invention. It is a figure which shows the mode of precipitation of the algal body of a halophilic microalga by skim milk about the collection method of the halophilic microalgae concerning one Embodiment of this invention. It is a figure which shows the mode of precipitation of the algal body of a halophilic microalga by skim milk about the collection method of the halophilic microalgae concerning one Embodiment of this invention.

  Hereinafter, a method for recovering halophilic microalgae according to an embodiment of the present invention will be described in detail.

  As described above, the inventors have obtained new knowledge regarding a method for recovering halophilic microalgae using salting out by materials other than alcohol (precipitation due to protein denaturation). The method for recovering halophilic microalgae according to the present embodiment is a method for recovering halophilic microalgae that obtains algal bodies of algae belonging to halophilic microalgae using precipitation due to protein denaturation.

  The method for recovering halophilic microalgae according to the present embodiment includes a step of culturing halophilic microalgae in a culture solution containing salt, and adding and mixing an organic substance solution containing protein in the culture solution. It is characterized by including the process of standing still and isolate | separating a mixed solution into a precipitate and a supernatant liquid, and the process of collect | recovering the said algal bodies contained in a precipitate.

  In this embodiment, halophilic microalgae are Donariella spp., Marine cyanobacteria, Nostoc spp., Symploca spp., Prochloron spp., Microalgae used in the aquaculture industry, Skeletonema spp., Thalassiosira Genus species, Chaetoceros species, Isochrysis genus, Tetraselmis genus species, Monochrysis genus species, Chlorella genus species, and others with known salt tolerance include Spirulina genus, Synechococcus genus, Phaeodacty species A microalgae selected from the group consisting of

  The species of the genus Donariella is a kind of green algae that are eukaryotic algae. The species of the genus Donariella belongs to halophilic microalgae and is a salt-tolerant unicellular green algae, so it breeds in places with high salinity. Donariella does not have a cell wall. Carotenoids made by Donariella are considered to be excellent in antioxidant action that assists cell regeneration, and are used as, for example, foods or active ingredients such as cosmetics and drugs.

  The presence of a relatively high concentration of salt is necessary for growth of halophilic microalgae such as Donariella species. In the present embodiment, the culture solution has a salt concentration of 3.5% to 20%. When the culture solution has a salt concentration of 3.5% to 20%, halophilic microalgae can be more efficiently separated and recovered using precipitation due to protein denaturation. Preferably, the culture medium has a salt concentration of 15% to 16%.

  In this embodiment, the temperature of the mixed solution is in the range of 10 ° C to 30 ° C. If the temperature of the mixed solution is in the range of 10 ° C. to 30 ° C., halophilic microalgae can be separated and recovered more efficiently using precipitation due to protein denaturation. Preferably, the temperature of the mixed solution is 25 ° C. and can be precipitated at room temperature.

In the present embodiment, algal cell concentration in the culture medium is 10 ⁶ / ml. When the concentration of algal bodies in the culture solution is 10 ⁶ cells / ml, it is possible to sufficiently generate precipitates by salting out, and it is possible to separate and collect halophilic microalgae more efficiently. .

  In the present embodiment, an organic solution containing 5 to 10% by weight of protein is added to the culture solution. When an organic solution containing 5 to 10% by weight of protein is added to the culture solution, a precipitate can be generated sufficiently by salting out, and halophilic microalgae can be separated and recovered more efficiently. can do.

  In this embodiment, the organic substance solution containing protein contains skim milk (skim milk powder), milk, soy milk or eggs. Skimmed milk, cow's milk, soy milk, or egg can produce a sufficient amount of salt by salting out by utilizing precipitation due to protein denaturation because the protein component is inexpensive and easy to procure.

  In the case of salting out with ethanol, the precipitation efficiency is increased by cooling the mixed solution. However, in the case of salting out with an organic solution containing proteins such as skim milk, precipitation can be sufficiently generated even at room temperature.

  In the case of skim milk, if skim milk is procured from waste milk or the like, it can be expected as a means for efficiently collecting halophilic microalgae at a low cost.

  Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

(Recovery method of halophilic microalgae using salting-out with materials other than alcohol)
The inventors added pure water to commercially available artificial seawater (powder) to prepare a culture solution having a salt concentration of about 15% by weight. Donariella was cultured in a culture solution for 14 days, and the culture solution was dispensed into tubes. Next, various materials were added to each tube, mixed, and allowed to stand for 10 minutes to separate the mixed solution into a supernatant and a precipitate. The supernatant and the precipitate were each observed with an optical microscope.

(Test results)
In the said Example, materials other than various materials are not added to each tube, and the centrifugation is not performed. In addition, when various materials were added, strong stirring was not performed and mixing was performed under mild conditions. The time required for precipitation was substantially about 10 minutes. The observation results of salting out with various materials are shown in FIGS. 2 (a) and 2 (b).

  As shown in FIGS. 2 (a) and 2 (b), a culture solution (Cul.) Was used as a control. Moreover, six types of organic material (FIG. 2 (a)) and five types of inorganic material (FIG. 2 (b)) were used as various materials.

  As shown in FIGS. 2 (a) and 2 (b), in the control, only Donariella alga bodies were observed in the culture solution.

  As shown in FIG. 2A, in six types of organic materials, in ethanol, acetone, glycerin, and polyvinyl alcohol, the mixed solution is separated into a supernatant and a precipitate by salting out. However, since the amount of increase in liquid due to salting out is large, there remains a problem of the processing amount of drainage (supernatant).

  As shown in FIG. 2 (a), FIG. 3 and FIG. 4, it was confirmed that skim milk precipitated in about 10 minutes and the collection efficiency of alga bodies was high. Moreover, in skim milk, since the increment of a liquid quantity is small, the burden of waste water treatment is suppressed.

  In precipitation due to protein denaturation, protein components in the organic solution are denatured by the presence of salt, and the molecular structure of the protein changes, so that halophilic microalgae are precipitated together with the protein components. The salt content in the culture solution is contained in the supernatant.

  In addition, as shown in FIG. 2 (b), although all the five types of inorganic materials have algal bodies recovered slightly, recovery efficiency is poor and algal bodies that are not precipitated near the liquid surface are confirmed. It was done.

  As described above, according to the method for recovering halophilic microalgae according to the present embodiment, the protein component in the organic solution is denatured by the presence of salt, and the molecular structure of the protein is changed. Precipitates with the protein component. Further, the salt content in the culture solution is contained in the supernatant.

  As a result, halophilic microalgae are present in the precipitate together with the protein components, and the salt content is contained in the supernatant. Therefore, halophilic microalgae can be separated efficiently using precipitation due to protein denaturation. Can be recovered. Moreover, since there is little increment of the liquid amount of the organic substance solution to add, the burden of the processing amount of a supernatant liquid (drainage) is suppressed.

  Moreover, not only Donariella species but also various halophilic microalgae other than Donariella can be efficiently separated and recovered using precipitation due to protein denaturation.

  In addition, when the culture solution has a salt concentration of 3.5% to 20%, halophilic microalgae can be more efficiently separated and recovered using precipitation due to protein denaturation.

  Moreover, if the temperature of a mixed solution is the range of 10 to 30 degreeC, a halophilic microalgae can be isolate | separated and collect | recovered still more efficiently using precipitation by protein denaturation.

Moreover, if the algal body concentration in the culture solution is 10 ⁶ cells / ml, it is possible to sufficiently generate precipitates by utilizing precipitation due to protein denaturation, and to make halophilic microalgae even more efficient. Can be separated and recovered.

  In addition, when an organic solution containing 5 to 10% by weight of protein is added to the culture solution, halophilic microalgae can be separated and recovered more efficiently using precipitation due to protein denaturation. Can do.

  In addition, since skim milk can be used, protein components are inexpensive and easy to procure. For example, in the case of an organic solution containing protein components, such as those used for eating and drinking, halophilic salts are obtained by utilizing precipitation due to protein denaturation. The microalgae can be separated and recovered more efficiently.

  In addition, in the case of salting out with ethanol, the precipitation efficiency is increased by cooling the mixed solution. However, in the case of precipitation with skim milk, a precipitate can be sufficiently generated even at room temperature.

  Further, in the case of skim milk, if skim milk is procured from milk discharge or the like, it can be expected as a means for efficiently collecting halophilic microalgae at a low cost.

  It should be noted that the method for recovering halophilic microalgae of the present invention is not limited to the above-described embodiment, and can of course be changed as appropriate without departing from the gist of the present invention.

  In the above embodiment, the halophilic microalgae are Donariella spp., Nostoc spp., Symploca spp, Prochloron spp, Skeletonema spp., Thalassiosira spp., Chaetoceros spp., Isochrysis spp, Tetraselmis spp. , A microalga selected from the group consisting of Chlorella genus, Spirulina genus, Synechococcus genus, Phaeodactylum genus, Bangia genus, but is not limited thereto. If it is a halophilic microalga such as Donariella sp., It can be efficiently recovered using precipitation by salting out (precipitation due to protein denaturation).

  In the said embodiment, although a culture solution has a salt concentration of 3.5%-20%, it is not limited to this. Depending on the halophilic microalga used, it is possible to use a culture solution having an appropriate salt concentration.

  In the said embodiment, although the temperature of a mixed solution is the range of 10 to 30 degreeC, it is not limited to this. Depending on the halophilic microalga used, it is possible to use an appropriate temperature.

In the above embodiments, algal cell concentration in the culture medium is a 10 ⁶ / ml, but is not limited thereto. Depending on the halophilic microalgae used, it is possible to use an appropriate algal body concentration.

  In the said embodiment, although the organic substance solution containing 5-10 weight% protein is added with respect to a culture solution, it is not limited to this. Depending on the halophilic microalgae used, it is possible to use organic solutions containing suitable proteins.

  In the said embodiment, skim milk was used as an organic substance solution containing protein, However, It is not limited to this. Depending on the halophilic microalga used, it is possible to use organic solutions containing suitable proteins such as milk, soy milk or eggs.

  In the above-described embodiment, a step of mixing and homogenizing with a buffer flow may be further included after the addition of the organic solution containing the protein to the culture solution. The buffer solution stream allows the culture solution and the organic solution containing the protein to be mixed more uniformly.

  In the said embodiment, you may further include the process of collect | recovering the salt contained in a supernatant liquid. Moreover, in the said embodiment, you may further include the process of returning the collect | recovered salt in a culture solution again and reusing. By doing so, as the salt content necessary for culturing halophilic microalgae in the culture solution, the recovered salt can be returned to the culture solution again and reused more efficiently.

  The method for recovering halophilic microalgae of the present invention is effectively used in a method for recovering halophilic microalgae that can be efficiently separated and recovered using precipitation by salting out (denaturation of protein). The

Claims (10)

A method for recovering halophilic microalgae, which obtains algal bodies of algae belonging to halophilic microalgae using precipitation due to protein denaturation,
Culturing the halophilic microalgae in a culture medium containing salt;
Adding an organic solution containing protein to the culture solution, mixing and allowing to stand, and separating the mixed solution into a precipitate and a supernatant;
A step of recovering the algal bodies contained in the precipitate, and a method for recovering halophilic microalgae.   The halophilic microalgae are Donariella sp., Nostoc sp., Symploca sp., Prochloron sp., Skeletonema sp., Thalassiosira sp., Chaetoceros sp., Isochrysis sp. The method for recovering halophilic microalgae according to claim 1, wherein the microalgae are selected from the group consisting of Spirulina spp, Synechococcus spp, Phaeodactylum spp, and Bangia spp.   The method for recovering halophilic microalgae according to claim 1 or 2, wherein the culture solution has a salt concentration of 3.5% to 20%.   The method for recovering halophilic microalgae according to any one of claims 1 to 3, wherein the temperature of the mixed solution is in the range of 10 ° C to 30 ° C. The algal concentration in the culture solution is 10 ⁶ / ml, the recovery method of halophilic microalgae according to any one of claims 1 to 4.   The method for recovering halophilic microalgae according to any one of claims 1 to 5, wherein an organic solution containing 5 to 10% by weight of the protein is added to the culture solution.   The method for recovering halophilic microalgae according to any one of claims 1 to 6, further comprising a step of mixing and homogenizing with a buffer flow after the addition of the organic solution containing the protein to the culture solution.   The method for recovering halophilic microalgae according to any one of claims 1 to 7, further comprising a step of recovering the salt contained in the supernatant.   The method for recovering halophilic microalgae according to any one of claims 1 to 8, further comprising a step of returning the recovered salt to the culture solution again and reusing it. The method for recovering halophilic microalgae according to any one of claims 1 to 9, wherein the organic solution containing protein comprises skim milk, milk, soy milk, or egg.