KR102009554B1 - Method of culturing photosynthetic microorganism using bicarbonate buffer produced by using carbon dioxide in flue gas and inorganic phosphate buffer - Google Patents

Abstract

The present invention relates to a method for culturing bicarbonate buffer prepared using carbon dioxide in flue gas, and photosynthetic microorganisms using inorganic phosphate buffer, and more particularly, to a flue gas containing carbon dioxide in a mixed solution of an aqueous base solution and an inorganic phosphate buffer. The present invention relates to a method for culturing photosynthetic microorganisms by supplying a flue gas saturation buffer system and inoculating a medium and photosynthetic microorganisms to generate useful substances.
The mixed buffer system of bicarbonate buffer and inorganic phosphate buffer using carbon dioxide in the flue gas according to the present invention has excellent buffering effect against acidity and at the same time can supply carbon and nutrient sources to photosynthetic microorganisms, thereby preventing the inhibition of microalgae productivity. It is possible to prevent the air pollution by the emission, and it can be applied to the mass cultivation process of photosynthetic microorganisms that produce useful materials because it is more cost-effective than the existing HEPES buffer and Na ₂ Glycerophosphate · 5H ₂ O.

Description

Method of culturing photosynthetic microorganism using bicarbonate buffer produced by using carbon dioxide in flue gas and inorganic phosphate buffer}

The present invention relates to a method for culturing bicarbonate buffer prepared using carbon dioxide in flue gas, and photosynthetic microorganisms using inorganic phosphate buffer, and more particularly, to a flue gas containing carbon dioxide in a mixed solution of an aqueous base solution and an inorganic phosphate buffer. The present invention relates to a method for culturing photosynthetic microorganisms by supplying a flue gas saturation buffer system and inoculating a medium and photosynthetic microorganisms to generate useful substances.

The burning of fossil fuels such as coal, petroleum and natural gas for energy production is a major cause of increasing atmospheric CO2 concentrations, which contributes to global warming. 0.95 kg of carbon dioxide is generated to produce 1 kWh. In order to reduce the carbon dioxide emissions, geological carbon capture technology has been developed, but this is not only costly, but there are also concerns about carbon dioxide leakage due to earthquakes and groundwater contamination. An ideal alternative to capturing carbon dioxide is to fix it in the form of biomass using biological mechanisms. However, conventional methods of using crops such as soybeans, palm trees, corn, canola and jatropha have a problem that these plants are not only food resources but also low yields (Plasynski, SI et al., Crit. Rev. Plant Sci. 28: 123-138, 2009).

Photosynthetic microbes, on the other hand, are not only highly productive but also produce valuable by-products without competing with food resources. However, in the cultivation of photosynthetic microorganisms, it is costly to continuously capture carbon dioxide and supply it as a photosynthetic raw material, which is an obstacle to biomass production. In addition, when carbon dioxide is supplied to the culture medium of photosynthetic microorganisms, acidification of the culture medium proceeds according to the following chemical formula, which may inhibit the growth of microorganisms.

CO ₂ + H ₂ O → H ₂ CO ₃

^{_{H 2 CO 3 → HCO 3 -}} + H +

On the other hand, bicarbonate (HCO 3 ⁻ ) can be utilized as a raw material for photosynthesis. The carbon concentration mechanism (CCM) developed in cyanobacteria and microalgae can transport both carbon dioxide and bicarbonate ions through cell membranes. Carbon dioxide and bicarbonate ions transported into cells are mainly in the form of bicarbonate ions. In particular, eukaryotic microalgae, such as Chlamydomonas, have inorganic carbon (Ci) transporters in the chloroplasts, allowing bicarbonate ions to accumulate and store in the chloroplast strom. In addition, when bicarbonate is added to the culture, H ⁺ may be consumed by the equilibrium of the following formula.

_{^{HCO 3 - + H + → CO}} 2 + H 2 O

Phosphorus, on the other hand, is another important nutrient for microalgal growth and culture. Phosphorus is a source of phospholipids, nucleotides and nucleic acids, and is involved in energy transfer (ATP) and several intracellular signal transductions. Cells can accumulate phosphorus up to about 3% of body composition in a phosphorus-rich environment and are less effective than nitrogen deficiency, but phosphorus deficiency is known to induce stress environments and lipid deficiencies in some microalgal species (Price, GD). et al., J. Exp . Bot. 59: 1441-1461, 2008). Phosphorus is an essential nutrient for cell growth, so cells can accumulate phosphorus in the cell in the form of polyphosphates.

In the past, HEPES (2- [4- (2-hydroxyethyl) piperazin-1-yl] ethanesulfonic acid) buffer was used to prevent acidification of the culture medium in photosynthetic microorganism culture, and the phosphate source was Na ₂ Glycerophosphate · 5H ₂ O. Used. However, since HEPES buffer and Na ₂ Glycerophosphate.5H ₂ O are expensive, they are burdensome to apply to the mass culturing process of photosynthetic microorganisms producing useful substances.

Therefore, the present inventors have made diligent efforts to solve the above problems, and when culturing photosynthetic microorganisms using a bicarbonate / carbonate buffer system generated by dissolving carbon dioxide in exhaust gas in a mixed solution of an aqueous base solution and an inorganic phosphate, the existing HEPES Compared to the buffer, the ability to prevent acidification of the microbial culture solution and at the same time improved the growth of microorganisms to confirm the production of useful substances including biomass, to complete the present invention.

It is an object of the present invention to provide a method for culturing bicarbonate buffer prepared using carbon dioxide in exhaust gas, and photosynthetic microorganism or microalgae using inorganic phosphate buffer.

The present invention to solve the above problems

In order to achieve the object, the present invention provides a (bi) bicarbonate / carbonate / phosphate buffer system by dissolving carbon dioxide by supplying a flue gas containing carbon dioxide to a mixed solution of a base aqueous solution and an inorganic phosphate buffer solution Formulating; And (b) adding a medium to the prepared bicarbonate / carbonate / phosphate buffer system, inoculating photosynthetic microorganisms, and culturing while supplying a carbon dioxide-containing flue gas. It provides a method for cultivating photosynthetic microorganisms using, and inorganic phosphate buffer.

The mixed buffer system of bicarbonate buffer and inorganic phosphate buffer using carbon dioxide in the flue gas according to the present invention has excellent buffering effect against acidity and at the same time can supply carbon and nutrient sources to photosynthetic microorganisms, thereby preventing the inhibition of microalgae productivity. It is possible to prevent the air pollution by the emission, and it can be applied to the mass cultivation process of photosynthetic microorganisms that produce useful materials because it is more cost-effective than the existing HEPES buffer and Na ₂ Glycerophosphate · 5H ₂ O.

1 is a process chart for the microalgal culture process using a bicarbonate / carbonate / phosphate buffer system according to the present invention.
FIG. 2 shows the pH and dissolved inorganic carbon concentration according to the gas adsorption conditions and the chemical adsorption of carbon dioxide according to the concentration of the basic aqueous solution when the carbon dioxide is aerated at a gas flow rate of 0.1 vvm for 12 hours or more in a strong base aqueous solution. Is a graph.
3 is a graph illustrating the effect of the concentration of soluble carbon species produced by carbon dioxide adsorption on cell growth according to the present invention.
Figure 4 shows the pH and dissolved inorganic carbon species according to the chemical adsorption of carbon dioxide by the concentration of inorganic phosphate when the carbon dioxide is aerated at a gas flow rate of 0.1 vvm in a mixed solution of a strong base aqueous solution and an inorganic phosphate buffer solution for more than 12 hours. This graph shows the concentration of carbon).
5 is a graph showing the results of cell growth according to the concentration of the strong base aqueous solution and inorganic phosphate buffer.
FIG. 6 shows biomass productivity (FIG. 6A) and astaxanthin productivity when H. pluvialis was cultured for a long time (60 days) using HEPES 20 mM, a buffer system according to the present invention, in an industrial exhaust flue gas condition. (FIG. 6B), pH (FIG. 6C), and dissolved carbon species concentration (FIG. 6D).

Hereinafter, the present invention will be described in more detail.

The present invention is to prevent the pH decrease by the continuous supply of high concentration of carbon dioxide in the microalgae cultivation process using a photo bioreactor and to constantly correct the pH of the culture medium to treat carbon dioxide in the flue gas discharged from the industry to the microalgae species sensitive to carbon dioxide concentration We want to provide a technology that can be used.

In the present invention, by supplying carbon dioxide in the flue gas to the mixed solution of the base aqueous solution and inorganic phosphate buffer solution to prepare a bicarbonate / phosphate buffer through carbon dioxide dissolution and inoculated with photosynthetic microorganisms, the culture solution by continuously supplying carbon and nutrient sources It was confirmed that the acidification of the microorganism was prevented and the growth inhibition effect of the microorganism did not occur, so that useful substances including biomass could be stably produced from the microorganism.

Accordingly, the present invention provides a bicarbonate / carbonate / phosphate buffer system by dissolving carbon dioxide by supplying (a) a flue gas containing carbon dioxide to a mixed solution of a base aqueous solution and an inorganic phosphate buffer solution. Formulating; And (b) adding a medium to the prepared bicarbonate / carbonate / phosphate buffer system, inoculating photosynthetic microorganisms, and culturing while supplying a carbon dioxide-containing flue gas. And a method for culturing photosynthetic microorganisms using inorganic phosphate buffer.

In the present invention, the carbon dioxide may be obtained through a purification process including at least two or more steps of dedusting, desulfurization, denitrification, and dechlorination in exhaust gas.

In the present invention, the base may be sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia (NH ₄ OH), calcium hydroxide (Ca (OH) ₂ ) or magnesium hydroxide (Mg (OH) ₂ ).

In the present invention, the inorganic phosphate buffer solution may be a mixed solution of K ₂ HPO ₄ and KH ₄ PO ₄ .

In the present invention, the carbon dioxide content in the exhaust gas may be 3 to 50%, but is not necessarily limited thereto, and the content of carbon dioxide may vary depending on the type of carbon dioxide generating source.

In the present invention, the concentration of the base may be 5 to 50 mM, preferably 5 to 20 mM, more preferably 10 mM strong base (KOH) when using a strong base, but is not limited thereto. It is not.

In the present invention, the concentration of the inorganic phosphate may be 0.01 to 5 mM, preferably 0.1 to 1 mM, more preferably 1 mM, but is not limited thereto.

In the present invention, the buffer (buffer) is not significantly affected when the acid or base is added from the outside, and maintains a constant hydrogen ion concentration, generally a mixture of weak acid and its salt or mixed solution of weak base and its salt It acts as a buffer.

The dissolved carbon dioxide in accordance with the present invention is HCO ₃ ^- present in the aqueous solution / CO ₃ ^2- buffer state, which has the effect as a conjugate acid / conjugate base species. The bicarbonate buffer can be used to maintain a constant pH during the microalgae culture, but at a CO ₂ concentration of more than a certain range (> 5% v / v), the pH correction effect is inhibited. In the present invention, the bicarbonate buffer system inorganic phosphate buffers in the ^{_{- (HCO 3 / CO 3 2-}} ) (H 2 PO 4 - / HPO 4 2 -) by using a mixed buffer system (bicarbonate / carbonate / phosphate buffer system) fine by increasing the buffering capacity Long-term culture of algae not only has the effect of correcting the pH, but also prevents the inhibition of microalgae productivity.

In addition, since the optimum pH conditions are different depending on the photosynthetic microorganism or microalgae to be cultured, the exhaust gas saturation buffer system of the present invention has a carbon dioxide content, an exhaust gas supply rate, and an exhaust gas supply according to the optimum pH of the photosynthetic microorganism. The composition can be adjusted by controlling the time, base and concentration of inorganic phosphate.

In the present invention, the photosynthetic microorganism is Chlorella vulgaris, Chlorella sorokiniana, Spirulina genus, Dunaliella genus, Hematococcus fluvialis, Haematococcus pluvialis , Microalgae such as genus Schizochytrium, genus Crypthecodinium, genus Chlamydomonas, genus Neochloris, and genus Aphanizomenon or cyanobacteria It may be characterized by photosynthetic bacteria, such as), but any microorganism that can use CO ₂ as a carbon source can be used without limitation.

In the present invention, the step (b) may further include the step of generating a useful material by photosynthetic microbial culture, but is not limited thereto.

In the present invention, the useful substance may be a health food, bioplastics, beta carotene, isotope compounds, astaxanthin, DHA oil, biodiesel, bio ethanol, soil improver or bio fertilizer, but is not limited thereto. It is not.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. However, these examples and the like are intended to explain the present invention in more detail, and it will be apparent to those skilled in the art that the scope of the present invention is not limited thereto.

Experimental Materials and Culture Conditions

The strain used in the present invention is Haematococcus It was purchased from National Institute for Environmental Studies, Tsukuba, Japan as pluvialis NIES-144. The medium used in this experiment is NIES-C and NIES-N medium and its components are shown in Table 1 below.

NIES-C NIES-N ingredient Content (/ L) ingredient Content (/ L) Ca (NO 3) ₂ 0.15 g CaCl ₂ · 2H ₂ O 0.13 g KNO ₃ 0.10 g KCl 0.07 g Na ₂ Glycerophosphate5H ₂ O
(Replaced by inorganic phosphate buffer) 0.05 g Na ₂ Glycerophosphate5H ₂ O
(Replaced by inorganic phosphate buffer) 0.05 g MgSO _{4 7} H ₂ O 0.04 g MgSO _{4 7} H ₂ O 0.04 g Thiamine 0.01 mg Thiamine 0.01 mg Biotin 0.10 μg Biotin 0.10 μg Vitamin b12 0.01 μg Vitamin b12 0.01 μg PIV metal solution
(per liter)
Na ₂ EDTA 1 g
FeCl ₃ 6H ₂ O 0.196 g
MnCl ₂ 4H ₂ O 0.036 g
ZnSO ₄ 7H ₂ O 0.022 g
CoCl ₂ · 6H ₂ O 4 mg
Na ₂ MoO ₄ 2H ₂ O 2.5 mg 3 ml PIV metal solution
(per liter)
Na ₂ EDTA 1 g
FeCl ₃ 6H ₂ O 0.196 g
MnCl ₂ 4H ₂ O 0.036 g
ZnSO ₄ 7H ₂ O 0.022 g
CoCl ₂ · 6H ₂ O 4 mg
Na ₂ MoO ₄ 2H ₂ O 2.5 mg 3 ml

In addition, the outdoor culture conditions of the H. pluvialis mass culture process under autotrophic conditions are shown below.

<Cultivation conditions>

NIES-C medium: autotrophic medium (autotrophic medium, purpose: growth)

NIES-N medium: autotrophic medium (autotrophic medium, purpose: to induce astaxanthin accumulation through nutrient stress)

-Gas supply: Based on carbon dioxide and air mixed gas, the concentrations were tested in air (control), 5% CO ₂ , 10% CO ₂ and 15% CO ₂ (v / v), respectively. It was supplied by Pangyo branch office and the concentration of CO ₂ contained in the flue gas was observed to be about 3 ~ 6%.

Injection flow rate: 0.1 vvm (vessel volume per minute)

Culture temperature: 23 ± 3 ℃

-Photoperiod: (approximately) contrast cycle 12: 12

Reactor type: Tubular transparent optical bioreactor, agitated using air bubbles in the form of a bubble column of 5L volume

-Light condition at growth: 50 ~ 70 μE / m ² / s

-Light condition in inductor: 300 ~ 500 μE / m ² / s

-Basic solution used for the preparation of inorganic carbon species buffer using chemical adsorption of carbon dioxide: 0mM (control), 10mM, 20mM, 30mM for each KOH

-Inorganic phosphate buffer composition to enhance pH correction effect: (When preparing 1M solution) A mixed solution of 163.73g / L K ₂ HPO ₄ and 8.17 g / L KH ₄ PO ₄ was respectively added 0 mM (control, Na ₂ as phosphate source). 0.05 g / L Glycerophosphate 5H ₂ O), 0.1 mM, 0.5 mM and 1.0 mM were injected into the culture to test the effect

Example  1. Optimization of Bicarbonate Buffer

As shown in FIG. 1, air, 5% CO ₂ , 10% CO ₂ , and 15% CO ₂ (v / v) were respectively supplied to different concentrations of the strong base (KOH) aqueous solution to prepare a bicarbonate buffer aqueous solution. At this time, the reactor was used in the form of a bubble column (bubble column) made of light-transmissive vinyl, the supply gas flow rate was constantly supplying gas at 0.1 vvm. The strong base aqueous solution rapidly raises the pH in the reactor, and thus carbon dioxide is dissolved in the strong base aqueous solution through the following chemical reaction.

^{_{CO 2 + OH - ↔ HCO 3}} -

_{^{HCO 3 - + OH - ↔ CO}} 3 - + H 2 O

Adsorption of carbon dioxide at high pH is a rate determining step, which is advantageous in terms of mass transfer by reducing the average size of the air bubbles to increase the reaction surface. To this end, the present invention used a gas distributor made of porous stone material.

The carbon dioxide dissolution reaction reaches a steady-state in which only carbon dioxide mixed gas is continuously supplied without any inflow and outflow in the reactor, and the reaction proceeds in a batch for more than 12 hours.

In order to investigate the preparation of the dissolved inorganic carbon species solution through the chemical adsorption of CO ₂ and the buffer efficacy of the microalgae broth, firstly, different concentrations of aqueous KOH solution were injected into the photobioreactor, and then the CO ₂ dissolution reaction was brought to a steady state. Gas was injected at a constant flow rate for more than 24 hours, and at this time, a bubble column reactor was installed as shown in FIG. 1 to inject carbon dioxide mixed gas and exhaust gas of various concentrations.

FIG. 2 shows the pH and dissolved inorganic carbon concentration according to the gas adsorption conditions and the chemical adsorption of carbon dioxide according to the concentration of the basic aqueous solution when the carbon dioxide is aerated at a gas flow rate of 0.1 vvm for 12 hours or more in a strong base aqueous solution. Is a graph. The gas conditions supplied at this time are air (control) (FIG. 2A), 5% (FIG. 2B), 10% (FIG. 2C), and 15% CO ₂ (FIG. 2D) mixed gas.

As shown in FIG. 2A, the pH of KOH aqueous solution (10 mM, 20 mM, 30 mM) was very high at 12-13 under the air supply condition. On the other hand, the pH was decreased to about 6.3 when only air was continuously supplied in the control (KOH 0 mM) condition. On the other hand, as shown in Fig. 2B-D it was observed that the pH converges within a certain range (between 7 and 8) regardless of the carbon dioxide concentration and KOH concentration in the CO ₂ mixed gas supply conditions. In addition, the concentration of dissolved inorganic carbon species also increased as the concentration of carbon dioxide and KOH aqueous solution increased. Thereafter, the culture medium was injected and inoculated with microalgae H. pluvialis cells, followed by outdoor culture under autotrophic conditions for about 18 days.

3 is a graph illustrating the effect of the concentration of soluble carbon species produced by carbon dioxide adsorption on cell growth according to the present invention. The gas conditions supplied at this time are air (control) (FIG. 3A), 5% (FIG. 3B), 10% (FIG. 3C), and 15% CO ₂ (FIG. 3D) mixed gas.

As shown in FIG. 3A, almost no cell growth occurred in the air supply condition. In addition, in the case of 0 mM KOH, the pH of the culture medium was 9.0, which was much higher than the optimum cell growth pH of 7.5, which observed that cell growth was inhibited as well as cell lysis. As shown in FIG. 3B, the biomass growth was the best under 5% CO ₂ mixed gas supply conditions, and the cell growth was confirmed to be the best with the final biomass concentration of 1.32 g / L in 10 mM aqueous KOH solution. In addition, as shown in FIG. 3C, even in a 10% CO ₂ mixed gas condition, the final biomass concentration was best at 0.80 g / L in 10 mM KOH aqueous solution, and the pH of the culture medium was 7.7 to 7.9 (KOH) under all basic aqueous solution conditions. PH 0) was maintained at 0 mM condition. In addition, as shown in FIG. 3D, under 15% CO ₂ mixed gas conditions, the pH of the culture solution was 6.8 to 7.3 (control 0 mM KOH is 5.5) under all basic aqueous solution conditions, and the concentration of dissolved carbon species was 400 to 1300 mg /. It was found to be very high as L, thereby inhibiting cell growth.

Example  2. Bicarbonate / Phosphate Buffer Optimization

The optimum conditions of the bicarbonate / phosphate buffer were derived by inducing a chemical adsorption reaction of CO _{2 into} the mixed aqueous solution of a strong base and an inorganic phosphate buffer.

The bicarbonate buffer was prepared by dissolving carbon dioxide in 10 mM KOH aqueous solution, and the inorganic phosphate buffer concentrations were 0.1 mM, 0.5 mM, and 1.0 mM, respectively, and the control group was mixed with CO ₂ mixed gas (5%, 10%, 15%, aeration as a control for more than 24 hours (aeration) proceeded the dissolution reaction.

Figure 4 shows the pH and dissolved inorganic carbon species according to the chemical adsorption of carbon dioxide by the concentration of inorganic phosphate when the carbon dioxide is aerated at a gas flow rate of 0.1 vvm in a mixed solution of a strong base aqueous solution and an inorganic phosphate buffer solution for more than 12 hours. This graph shows the concentration of carbon). The gas conditions supplied at this time are air (control) (FIG. 4A), 5% (FIG. 4B), 10% (FIG. 4C), and 15% CO ₂ (FIG. 4D) mixed gas.

As shown in FIG. 4A, since CO ₂ was hardly dissolved in the air supply condition as a control, even when the inorganic phosphate buffer was added, the pH was significantly high as 11.0 to 12.3, and thus it was not suitable for cell growth. In addition, as shown in FIG. 4B-D, when the 5%, 10%, and 15% CO ₂ mixed gas was supplied, the pH dropped to 6.8 to 7.5 under all conditions regardless of the addition of the inorganic phosphate buffer, but 15% CO ₂ When supplying a mixed gas, it was confirmed that the concentration of soluble carbon species was 410-720 mg / L, which was unsuitable for cell growth.

These results suggest that the pH drop in the mixed solution of the strong base solution and the inorganic phosphate buffer is caused by CO ₂ adsorption, and the influence of the inorganic phosphate buffer in this process is insignificant. 4B-D, the inorganic carbon species concentration after the CO ₂ dissolution reaction increases as the concentration of the supplied CO ₂ mixed gas increases, and also increases as the inorganic phosphate concentration increases.

Next, an experiment was performed to observe the cell growth results according to the concentration of the strong base aqueous solution and the inorganic phosphate buffer. At this time, 10% CO ₂ mixed gas was supplied, and the concentration of KOH aqueous solution for CO ₂ adsorption was 0 mM KOH, 10 mM, and 20 mM, respectively. In addition, the concentration of the inorganic phosphate buffer was 0 mM (control, addition of 0.05 g / L Na ₂ Glycerophosphate 5H ₂ O as phosphate source, Figure 5A), 0.1 mM (Figure 5B), 0.5 mM (Figure 5C), 1.0 mM (FIG. 5D), NIES-C medium stock and H. pluvialis seed were supplied to observe cell growth.

As a result, the dissolved carbon species concentration was about 420 mg / L when CO ₂ was adsorbed to 10 mM KOH strong base solution and 0.1 mM inorganic phosphate buffer mixed solution under 10% CO ₂ gas supply condition. The pH of the medium was about 7.2, and the cell growth was also the best.

Based on these results, the bicarbonate buffer prepared by CO ₂ lysis according to the present invention can be utilized as a carbon source for cell growth and has a pH buffering effect, but the high CO ₂ concentration greatly increases the dissolved carbon species concentration in aqueous solution, and excessive dissolution. carbon species concentration was confirmed that rather can inhibit cell growth, inorganic phosphate buffers residual inorganic phosphate as well as the supply of the required nutrient to the cell growth, such as bicarbonate buffer ^{_{(H 2 PO 4 - / HPO}} 4 2- ) Can be used as a buffer to calibrate pH.

Example  3. Biomass and Astaxanthin  Productivity, pH and Dissolution Carbon species  Concentration comparison

Next, the buffer system (KOH 10 mM, inorganic phosphate 0.1 mM) which showed the best microalgal growth through 20 mM HEPES buffer and Example 2, in order to compare the performance of the conventionally used HEPES buffer and the buffer system according to the present invention. Microalgae culture experiments were conducted for 60 days using biomass productivity (FIG. 6A), astaxanthin productivity (FIG. 6B), pH (FIG. 6C), and dissolved carbon species concentration (FIG. 6D). . At this time, the light demand of the cells was low in the growing season, so the low light intensity (50-70 μE / m ² / s) was supplied. In the induction period in which astaxanthin accumulates, the cells are high in order to cause malnutrition stress and light stress. Light (300-500 μE / m ² / s) of light was supplied and NIES-N medium was supplied.

As a result, the concentration of dissolved carbon species and pH were maintained constant compared to the existing HEPES buffer when the cells were cultured for a long time (FIG. 6C-D), and the biomass and astaxanthin productivity of the buffer system according to the present invention was increased even at low brightness. It was confirmed excellent (Fig. 6A-B).

With this result the present invention the microalgae in the check bar, a variety of CO ₂ emission industry hayeotneun the prior art that only can replace a HEPES as a buffer, not the algae culture can be in the high-concentration CO ₂ (~ 10%) condition It was confirmed that it can be effectively used in the biological CO ₂ reduction process used.

Claims (9)

Method for culturing photosynthetic microorganisms using bicarbonate buffer prepared using carbon dioxide in exhaust gas, and inorganic phosphate buffer comprising the following steps:
(a) By supplying a flue gas containing 5 to 10% (v / v) of carbon dioxide to a mixed solution of 5-15 mM base solution and 0.1-0.5 mM inorganic phosphate buffer solution, Establishing a carbonate / carbonate / phosphate buffer system; And
(b) adding a medium to the prepared bicarbonate / carbonate / phosphate buffer system, inoculating photosynthetic microorganisms, and culturing while supplying carbon dioxide-containing exhaust gas,
The inorganic phosphate buffer solution is characterized in that the mixed solution of K ₂ HPO ₄ and KH ₄ PO ₄ . The method of claim 1,
The carbon dioxide is a culture method, characterized in that obtained through a purification process comprising at least two or more steps of exhaustion, desulfurization, denitrification and dechlorination in the exhaust gas. The method of claim 1,
The base is sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia (NH ₄ OH), calcium hydroxide (Ca (OH) ₂ ) or magnesium hydroxide (Mg (OH) ₂ ) characterized in that the culture method. delete delete delete delete The method of claim 1,
The photosynthetic microorganisms include Chlorella vulgaris, Chlorella sorokiniana, Spirurlina, Dunaliella, Haematococcus pluvialis, and Szozoquitrium. Schizochytrium, Crypthecodinium, Chlamydomonas, Neochloris, Aphanizomenon or Cyanobacteria Cultivation method. The method of claim 1,
Cultivating method further comprises the step of producing a useful material by the photosynthetic microorganism culture of step (b).

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