JP5164057B2 - Culture medium for photosynthetic organisms using incinerated ash, method for producing the same, and method for culturing photosynthetic organisms - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a medium for culturing photosynthetic organisms, which effectively uses incinerated ash, which is a waste, as a component of the medium, and a method for producing the same. Furthermore, the present invention relates to a method for culturing photosynthetic organisms.

  In recent years, with the increase of incineration ash (combustion ash) emissions, technology for the treatment and effective utilization of incineration ash is required. Incineration ash is incineration of livestock waste including chicken manure, pig manure and cow manure, incineration of food waste, raw garbage and municipal waste, incineration of forest waste such as waste and thinned wood, sewage treatment plant It is generated in large quantities by incineration of surplus sludge discharged from the plant, incineration of various wastes discharged from various factories, and combustion of fossil fuels such as coal in thermal power plants and combustion furnaces.

  Landfill treatment is one of the first disposal methods for incinerated ash, but recently it has become difficult to secure a landfill site, and in addition to reducing the volume of incinerated ash, Development of effective utilization methods is strongly desired.

  Various effective utilization methods of incinerated ash have been studied so far. For example, in the cement field, utilization methods for cement raw materials, cement admixtures and concrete admixtures have been developed (Patent Document 1). In the civil engineering field, utilization methods for ground improvement materials, road roadbed materials, asphalt, and the like have been developed (Patent Document 2). In the building field, a method of using a building material board, an artificial lightweight aggregate, or the like has been developed (Patent Document 3). In the field of agriculture, forestry and fisheries, utilization methods for fertilizers, soil improvers and the like have been developed (Patent Document 4). Also disclosed is a method in which incinerated ash is mixed with another inorganic material or a curing agent such as cement, molded into a molded body, and used as a culture medium for algae that can float on water (Patent Document 5, Patent Document). 6).

  However, in order to utilize the incinerated ash generated in large quantities, there has been a strong demand for effective use in other new fields and for the production of useful substances.

  By the way, algae which are photosynthetic organisms are currently used in a wide range of fields such as food, feed and environment. For example, the green alga Chlorella is commercially available as a health food in the food field in the form of dry algae in the form of tablets and granules and hot water extract (extract) in the form of a drink. In the agricultural field, chlorella extract is also used as a plant growth agent and as a fertilizer for dry algal bodies. In the field of fisheries, it is used as an additive for rotifer production and aquaculture feed.

  In the food field, the blue-green algae Spirulina is used as a food material such as a nutritional supplement, or a blue pigment contained in an alga body as a food pigment. In the fishery field, it is used as a feed additive for appreciation fish and cultured fish, and in the livestock field, it is used as a feed additive for laying hens.

  More recently, as a measure against carbon dioxide, which causes global warming, algae such as chlorella are cultured under light irradiation to fix carbon dioxide in combustion exhaust gas discharged from thermal power plants and various factories. At the same time, the use of cultured algae for feed, the extraction and production of useful substances from algae, and the removal of hazardous chemicals is also being studied (patents) Reference 7 and Japanese Patent Application No. 2006-250005).

  However, when these photosynthetic organisms are artificially cultured under light irradiation to produce cells and useful substances, a dedicated medium suitable for culture is required. The medium must contain various inorganic nutrient salts such as salts containing nitrogen, phosphorus, potassium, sodium, magnesium, calcium, sulfur and iron, and salts of trace metals such as manganese, cobalt, zinc and molybdenum. Therefore, the production of the culture medium requires many kinds of chemicals, and it takes time and effort to prepare them, and the cost of the chemicals is also high, resulting in high costs.

  A method in which carbon dioxide is brought into contact with a solution obtained by bringing coal ash or the like into contact with water has been studied (Patent Document 7), but this method includes coal ash and the like. Since elements such as alkali metals and alkaline earth metals exist in the form of oxides, the amount of dissolution is extremely small by simply contacting with water, and there is a lack of nutritional components, making it difficult to efficiently cultivate photosynthetic organisms. there were.

  Therefore, there has been a strong demand for the development of an economical medium that can be easily and inexpensively prepared and that can efficiently cultivate a large amount of photosynthetic organisms, and that the medium can be used for production of photosynthetic organisms and production of useful substances.

JP 2003-146726 A JP 2003-251398 A JP-A-6-166579 JP 2006-297187 A JP 2000-245278 A JP-A-11-243944 JP-A-10-248553

  An object of the present invention is to effectively use the incinerated ash that is a waste and to provide a medium that can be used for culturing photosynthetic organisms simply and inexpensively. Another object of the present invention is to provide a method for culturing photosynthetic organisms using incinerated ash.

  As a result of earnest research to solve such problems, the present inventors have found that a solution obtained by dissolving incinerated ash with an acid can be used as a medium for culturing photosynthetic organisms such as algae, and completed the present invention. It came to do.

That is, the gist of the present invention is as follows.
(1) A culture medium for photosynthetic organisms containing a solution prepared by dissolving incinerated ash with an acid.
(2) The culture medium for photosynthetic organisms according to (1) above, wherein the acid is one or more selected from nitric acid, sulfuric acid and hydrochloric acid.
(3) The culture medium for photosynthetic organisms according to (1) or (2) above, wherein the incineration ash is incineration ash of chicken dung.
(4) The culture medium for photosynthetic organisms according to any one of (1) to (3) above, wherein an iron salt or a copper salt or both are further added to the solution.
(5) A method for cultivating photosynthetic organisms, wherein incinerated ash is dissolved with an acid, and the photosynthetic organism is cultured using the obtained solution.
(6) A method for producing a culture medium for photosynthetic organisms, which comprises preparing a solution by dissolving incinerated ash with an acid and producing a culture medium containing the solution.

  The culture medium of the present invention can be used as a medium for culturing photosynthetic organisms such as algae. Since incinerated ash, which is a waste, is used as a raw material when preparing the medium, it is possible to culture photosynthetic organisms and produce useful substances easily and inexpensively. Moreover, by using the incineration ash as a component of the culture medium, it is possible to effectively use and reuse the incineration ash that is industrial waste.

Hereinafter, the present invention will be described in detail.
Incinerated ash used in the present invention includes livestock waste such as chicken dung, pig dung and cow dung, raw garbage, municipal waste, food waste, forest waste such as waste and thinned wood, sewage treatment plant sludge, and factory Use ash discharged when burning various organic waste such as discharged waste, or ash discharged when burning solid fuel such as coal in a thermal power plant or combustion furnace, etc. be able to.

Among these, ash (chicken manure incineration ash) discharged by the combustion of chicken manure is particularly preferably used. The composition of incinerated chicken manure ash varies depending on the combustion conditions, etc., but is about 25 to about 55 wt% CaO, about 7 to about 25 wt% K ₂ O, about 9 to about 15 wt% P ₂ O ₅ , about 3 to about 12 wt% of SO _3, from about 1 to about 7 weight percent of Cl, from about 2 to about 3 wt% of MgO, 1 to less than about 3 wt% of _Na 2 O, and from about 1 to about 4 wt% by weight of SiO ₂ or the like, since the sodium, potassium, calcium, magnesium, is composed of useful elements such as phosphorus, it is suitable as a raw material for culture medium photosynthetic organisms.

  Examples of the acid that dissolves the incinerated ash include various acids such as mineral acids, organic acids, and carbonic acids. Among these, mineral acids such as nitric acid, sulfuric acid, and hydrochloric acid are preferably used. Any one of these nitric acid, sulfuric acid, and mineral acid may be used, or two or all three types may be used in combination. Since nitrate ions in nitric acid can be used as a nitrogen source necessary for the growth of photosynthetic organisms such as algae, it is preferable to contain at least nitric acid as a component, and most preferably a mixture of three acids of nitric acid, sulfuric acid and hydrochloric acid. It is an acid. In the case of using a mixed acid, the mixing ratio of each component can be appropriately set in consideration of incineration ash, the type of photosynthetic organism to be cultured, and the like. Generally, when nitric acid is 100 by volume ratio, sulfuric acid with the same molarity is about 5 to 20, and hydrochloric acid is about 10 to 30.

  A pH suitable for cultivation of photosynthetic organisms in which incinerated ash is added to these acids and dissolved by stirring or the like, and then undissolved incinerated ash is separated by means of centrifugation, filtration, etc., and the pH of the resulting solution is cultured. The culture medium of the present invention is obtained by adjusting to a medium concentration suitable for culturing photosynthetic organisms to be cultured by, for example, diluting with water if necessary. In the culture medium containing such incinerated ash solution, various elements such as sodium, potassium, calcium, magnesium, iron, and phosphorus present in the incinerated ash are dissolved in a salt state, and photosynthetic organisms such as algae are dissolved. Can be used as a nutrient when growing under photoautotrophic conditions.

  The culture medium of the present invention can be used in the state of a solution as described above. Alternatively, the solution may be dissolved and solidified with agar or the like to form a solid medium or a semi-fluid medium.

Furthermore, various salts can be added to the culture medium of the present invention as necessary. This makes it possible to supplement the nutrients necessary for the photosynthetic organism. Specific examples of the salt include iron salts such as FeSO ₄ · 7H ₂ O, copper salts such as CuSO ₄ · 5H ₂ O, and combinations of iron salts and copper salts. Nitrate is preferably added because it can be used as a nitrogen source, particularly when the acid that dissolves the incinerated ash is a mixed acid composed of only H ₂ SO ₄ and HCl.

  The amount of salt to be added varies depending on the type of incineration ash and the like, and is not particularly limited. For example, for a medium using chicken manure incineration ash as a raw material, the medium is diluted with water and adjusted to an appropriate pH. Preferably, the iron salt is about 0.1 to about 2 mg / L in terms of Fe and the copper salt is about 0.01 to about 0.03 mg / L in terms of Cu with respect to the medium. It is preferable to set the addition amount to about 2500 mg / L.

  Examples of photosynthetic organisms that can be cultured in a medium containing a solution prepared from incinerated ash as described above include the genus Chlorella, which is a green alga, and the genus Spirulina, which is a cyanobacteria. Instead, any photosynthetic organism can be cultured as long as it grows photoautotrophically, such as other plants such as algae, phytoplankton, seaweed, seaweed, photosynthetic bacteria, and vegetables. The photosynthetic organisms may be directly seeded in the culture medium of the present invention, or a precultured solution is obtained by previously culturing the photosynthetic organisms in a normal medium such as an algae medium such as MBM medium. The liquid may be added to the culture medium of the present invention. In addition, when the incinerated ash solution itself is used as a culture medium, for example, the incinerated ash solution can be used as a culture liquid (liquid fertilizer) in hydroponic culture (hydroponic culture etc.) such as vegetables.

  Furthermore, when photosynthetic organisms such as algae grow photoautotrophically under light irradiation, a carbon source is required. To secure this carbon source, for example, by shaking a container in which a culture medium is installed. Carbon dioxide in the atmosphere can be dissolved in the medium and used as a carbon source. In addition, the concentration of carbonate ions dissolved in the medium is increased by the addition of sodium hydrogen carbonate to the solution in which the incinerated ash is dissolved, or by aeration of gas containing air or carbon dioxide into the culture vessel. The growth rate and growth amount of photosynthetic organisms can be improved.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, it cannot be overemphasized that this invention is not limited only to these Examples.

  In the following Examples and Reference Examples, Chlorella vulgaris IAM C-27, Chlorella solokiniana obtained from the IAM Culture Collection of the University of Tokyo as a strain of the genus Chlorella, a green alga of a photosynthetic organism, (Chlorella sorokiniana) IAM C-212, Chlorella kessleri IAM C-531, Chlorella vulgaris IAM C-536, Chlorella vulgar I (Clorella vulgarh) ) IAM C-628, Chlorella vulgar separated and stored in the laboratory s) MKJ-34 (Japanese Patent Application No. 2006-250005) and Chlorella vulgaris (Chlorella vulgaris) were used C-1 (Japanese Patent Application No. 2006-250005).

  Furthermore, as a strain of the genus Spirulina, which is a cyanobacteria, Spirulina platensis NIES-39, Spirulina platensis NIES-45, Spirulina platensis (Spirulina platensis) obtained from the National Institute for Environmental Studies. ) NIES-46 and Spirulina platensis NIES-597 were used.

  For the pre-culture of the genus Chlorella, the MBM medium shown in Table 1, Table 2 and Table 3 was used, and under the light irradiation with a fluorescent lamp (5500 Lux, 12 hours dark-12 hours light) under the conditions of 30 ° C. A pre-culture solution was obtained by stationary culture for one day.

  For the preculture of Spirulina, the SOT medium or MA medium shown in Tables 4 and 5 was used, and the light was irradiated with a fluorescent lamp (5500 Lux, 12 hours dark-12 hours light) at 30 ° C. for 6 days. Was subjected to stationary culture to obtain a preculture solution.

(Example 1, Reference Example 1)
A culture medium using incinerated ash was prepared as follows. 50 ml of a mixed acid prepared by mixing 0.1 mol / L HNO ₃ , 0.1 mol / L H ₂ SO ₄ and 0.1 mol / L HCl at a volume ratio of 25: 3: 5 was put in a beaker, While stirring with a tic stirrer, chicken manure incineration ash was added little by little to dissolve the chicken manure incineration ash until the pH of the solution reached 5.4. Due to the dissolution treatment with acid, the equivalent of about 60% of the original weight of the chicken manure incineration ash was dissolved, and the volume of the incineration ash was reduced. A solution in which the incinerated ash was dissolved was centrifuged (10,000 rpm, 10 minutes) to remove undissolved incinerated ash, and a supernatant obtained by diluting 30 times with distilled water was used as a culture medium.

Next, 10 mL of the culture medium prepared using chicken manure incineration ash as described above was added to an L-shaped test tube, and sterilized by autoclaving (121 ° C., 15 minutes). After sterilization, inoculate 0.3 mL of the pre-culture solution of the above-mentioned various chlorella algae, and culture for 7 days under conditions of 30 ° C. and irradiation with fluorescent light (5500 Lux, 12 hours dark-12 hours light) Were subjected to shaking culture. The culture solution at the end of the culture and at the initiation of the culture, using ultraviolet-visible spectrophotometer (Shimadzu UVmini-1240) was measured and the absorbance _{(OD 660)} at a wavelength of 660 nm, growing from the difference of the absorbance _{(OD 660)} I asked for a degree.

  Further, the MBM medium used for culturing Chlorella was also cultured in the same manner to determine the degree of growth (Reference Example 1), and compared with the degree of growth in the culture medium according to the present invention. The measurement results are shown in FIG.

  As shown in FIG. 1, when cultured on the medium of the present invention using chicken manure incineration ash, although the degree of growth varies depending on the type of genus Chlorella, growth similar to that obtained when cultured on MBM medium is obtained. It has been found that the culture medium according to the invention can be used as a medium for Chlorella.

(Example 2, Reference Example 2)
10 mL of the incineration ash medium prepared using the chicken manure incineration ash in Example 1 was added to an L-shaped test tube, and sterilized by autoclaving (121 ° C., 15 minutes). After sterilization, inoculate 0.3 mL of a preculture of various Spirulina alga bodies for 7 days under conditions of culture temperature 30 ° C. and irradiation with fluorescent light (5500 Lux, 12 hours dark-12 hours light). Shaking culture was performed. The degree of growth was determined from the difference in absorbance (OD ₆₆₀ ) of the culture solution at the start of culture and at the end of culture. In addition, the SOT medium or MA medium used for culturing Spirulina was cultured in the same manner to determine the degree of growth (Reference Examples 2 and 3), and compared with the degree of growth in the culture medium according to the present invention. The measurement results are shown in FIG.

  As shown in FIG. 2, when cultured in a medium using chicken manure incineration ash, the degree of growth varies depending on the strain of the genus Spirulina, but almost the same growth as when cultured in the SOT medium or MA medium is obtained. Therefore, it has been found that the culture medium according to the present invention can be used as a Spirulina medium.

(Examples 3 to 6)
When preparing the culture medium, the composition of the mixed acid was changed to dissolve the incinerated ash, and the degree of growth in the obtained culture medium was examined. Specifically, 0.1 mol / L HNO ₃ , 0.1 mol / L H ₂ SO ₄ and 0.1 mol / L HCl were added at 25: 3: 5 (Example 3), 25: 3: 0. (Example 4), four mixed acids mixed at a volume ratio of 25: 0: 5 (Example 5) and 0: 3: 5 (Example 6) were used. Four kinds of mixed acids (50 mL) were put in a beaker, and chicken dung incineration ash was added little by little while stirring with a magnetic stirrer. The chicken dung incineration ash was dissolved until the pH of the solution reached 5.4. Centrifugation (10,000 rpm, 10 minutes) of the solution in which chicken manure incineration ash was dissolved to remove undissolved incineration ash, and the resulting four types of supernatants diluted 30 times with distilled water were used as the medium. It was.

Four types of culture media were added to an L-shaped test tube in an amount of 10 mL, and sterilized by autoclaving (121 ° C., 15 minutes). After sterilization, 0.3 ml of the preculture of Chlorella vulgaris MKJ-34 and Chlorella vulgaris C-1 was inoculated, and the light was irradiated with fluorescent light (5500 Lux, 12 Shaking culture was performed for 7 days under the conditions of time dark-12 hours light. The degree of growth was determined from the difference in absorbance (OD ₆₆₀ ) of the culture solution at the start of culture and at the end of culture. The measurement results are shown in Table 6.

As shown in Table 6, it is clear that any of the culture media of Examples 3 to 6 prepared with an acid containing two kinds of HNO ₃ , H ₂ SO ₄ and HCl can be used as a Chlorella genus medium. It became. Among them, in the culture medium prepared with a mixed acid containing all three types of acids HNO ₃ , H ₂ SO ₄ and HCl, both chlorella were found to have the highest growth. In addition, the growth degree of the culture medium prepared with a mixed acid composed of only H ₂ SO ₄ and HCl was slightly low. This is considered to be because there is little nitrogen source in the culture medium because it does not contain HNO ₃ . Therefore, when preparing the culture medium, it is preferable to contain three of HNO ₃ , H ₂ SO ₄ and HCl as the mixed acid for dissolving the incineration ash, and it is particularly preferable to contain HNO _3. It was.

(Examples 7 to 14)
In the preparation of the culture medium, a mixed acid prepared by mixing 0.1 mol / L HNO ₃ , 0.1 mol / L H ₂ SO ₄ and 0.1 mol / L HCl at a volume ratio of 25: 3: 5 was used. Use a 30-fold diluted solution obtained by dissolving pig dung incineration ash (Example 7) or swine dung and charcoal incineration ash (Example 8) obtained by burning a mixture of pig dung and charcoal Used as culture medium. After adding 10 mL of these culture media to an L-shaped test tube and sterilizing with an autoclave (121 ° C., 15 minutes), inoculated with 0.3 ml of a pre-culture solution of Chlorella vulgaris (Klorella vulgaris) MKJ-34 and cultured. The shaking culture was performed for 7 days under the conditions of a temperature of 30 ° C. and light irradiation with a fluorescent lamp (5500 Lux, 12 hours dark—12 hours light). The degree of growth was determined from the difference in absorbance (OD ₆₆₀ ) of the culture solution at the start of culture and at the end of culture.

Further, to the culture medium prepared from chicken manure incineration ash as described above, a medium (Example 9) in which FeSO ₄ · 7H ₂ O was further added to a concentration of 2 mg / L, CuSO ₄ · 5H ₂ O was added. Medium added to a concentration of 0.079 mg / L (Example 10), and FeSO ₄ · 7H ₂ O and CuSO ₄ · 5H ₂ O to a concentration of 2 mg / L and 0.079 mg / L, respectively. The culture medium added to (Example 11) was prepared, shake culture was performed in the same manner, and the degree of growth was determined.

Furthermore, a culture medium prepared from pig excrement / charcoal incineration ash with FeSO ₄ · 7H ₂ O added to a concentration of 2 mg / L (Example 12), CuSO ₄ · 5H ₂ O Medium added to a concentration of 0.079 mg / L (Example 13), and FeSO ₄ · 7H ₂ O and CuSO ₄ · 5H ₂ O to a concentration of 2 mg / L and 0.079 mg / L, respectively. A medium (Example 14) added to was prepared and shake-cultured to determine the degree of growth.

The above measurement results are shown in FIG.
As shown in FIG. 3, it was found that even a culture medium prepared from swine dung and charcoal incinerated ash can be used as a medium for culturing a photosynthetic organism such as chlorella. Moreover, in the culture medium prepared using chicken manure incineration ash and pig manure / charcoal incineration ash, the addition of a small amount of iron salt and copper salt tended to increase the growth rate compared to the case of no addition.

(Example 15)
Incinerating chicken manure using mixed acid prepared by mixing 0.1 mol / L HNO ₃ , 0.1 mol / L H ₂ SO ₄ and 0.1 mol / L HCl to a volume ratio of 25: 3: 5 280 mL of 30-fold diluted culture medium obtained by dissolving ash was added to a 300 mL Erlenmeyer flask and sterilized by autoclaving (121 ° C., 15 minutes). After sterilization, 20 mL of a pre-culture solution of Chlorella vulgaris MKJ-34 was added, and a mixed gas (CO ₂ 5%, air 95) in which CO ₂ gas was mixed with air so that the CO ₂ concentration was 5%. %) And aeration at a flow rate of 300 mL / min, aeration culture is performed for 7 days under the conditions of a culture temperature of 30 ° C. and light irradiation with a fluorescent lamp (5500 Lux, 12 hours dark—12 hours light). The degree of growth was determined from the difference in absorbance (OD ₆₆₀ ) of the culture solution at the end of the culture.

(Example 16)
Further, FeSO ₄ · 7H ₂ O and CuSO ₄ · 5H ₂ O were added to the culture medium in Example 15 so as to have concentrations of 2 mg / L and 0.079 mg / L, respectively. After 280 mL of the culture medium added with the iron salt and copper salt was placed in a 300 mL Erlenmeyer flask and sterilized by autoclaving (121 ° C., 15 minutes), Chlorella vulgaris (Klorella vulgaris) MKJ- 34 aeration cultures were performed, and the degree of growth was determined from the difference in the absorbance (OD ₆₆₀ ) of the culture solution at the start and end of the culture.

(Reference Example 4)
Furthermore, in order to compare with aeration culture in the culture medium of Examples 15 and 16, 280 mL of MBM medium was put into a 300 mL Erlenmeyer flask and sterilized by autoclave (121 ° C., 15 minutes), and then the same as in Example 15 Using the method, Chlorella vulgaris (Klorella vulgaris) MKJ-34 was aerated and the degree of growth was determined from the difference in absorbance (OD ₆₆₀ ) of the culture solution at the start and end of the culture.
The measurement results of Examples 15 and 16 and Reference Example 4 are shown in Table 7.

As shown in Table 7, it was found that chlorella can be cultured by aeration culture using a medium prepared from incinerated ash, as in the case of shaking culture in FIG. Here, compared with the result of the aeration culture in the MBM medium, the growth degree of the aeration culture in Example 15 was slightly low, but the trace amounts of FeSO ₄ · 7H ₂ O and CuSO ₄ · 5H ₂ O were added to the culture medium. It was found that the aeration culture in Example 16 gave a higher degree of growth than that of the MBM medium. Therefore, the medium according to the present invention is also suitable for culturing photosynthetic organisms under aeration culture, and depending on the type of incinerated ash used as a raw material, the growth degree can be further improved by supplementing with a small amount of appropriate salts. It is.

  As described above, according to the present invention, a solution obtained by dissolving incinerated ash with an acid contains nutrients necessary for the growth of photosynthetic organisms such as algae, and therefore can be used as a medium. . Further, since the culture medium of the present invention can cultivate photosynthetic organisms such as algae by shaking culture or aeration culture under light irradiation, culture of various photosynthetic organisms including chlorella and spirulina and production of organisms, In addition, it can be used effectively in the production of useful substances produced by these photosynthetic organisms.

It is a graph which shows the measurement result of the growth degree of various chlorella genera in Example 1 and Reference Example 1. It is a graph which shows the measurement result of the growth degree of various Spirulina in Example 2, Reference Examples 2 and 3. It is a graph which shows the measurement result of the growth degree of the chlorella in Examples 7-14.

Claims (5)

A culture medium for photosynthetic organisms containing a solution prepared by dissolving incinerated ash with a mixed acid in which nitric acid, sulfuric acid and hydrochloric acid are combined . The culture medium for photosynthetic organisms according to claim 1, wherein the incineration ash is incineration ash of chicken manure. The culture medium for photosynthetic organisms according to claim 1 or 2 , wherein an iron salt or a copper salt or both are further added to the solution. A method for cultivating photosynthetic organisms, wherein incinerated ash is dissolved with a mixed acid obtained by combining nitric acid, sulfuric acid and hydrochloric acid, and the photosynthetic organism is cultured using the obtained solution. A method for producing a culture medium for photosynthetic organisms, comprising preparing a solution by dissolving incinerated ash with a mixed acid combining nitric acid, sulfuric acid and hydrochloric acid, and producing a culture medium containing the solution.

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