JPH07289239A - Method for culturing photosynthetic organism - Google Patents

Abstract

PURPOSE:To carry out photosynthesis at a high culture rate without stirring a culture solution, by supplying carbon dioxide while making the culture solution containing Anacystis nidulans flow along the surface of a liquid film forming plate and radiating the culture solution with light rays. CONSTITUTION:A CO2-containing gas is supplied from a gas feeding means 10 to a culture solution 4 containing Anacystis nidulans while making the culture solution flow along the surface of a liquid film forming plate 2 and the culture solution is irradiated with light rays from a light source 7. The thickness of a liquid film 6 of the culture solution can be readily controlled, CO2 is readily taken in the liquid film and no difference in irradiation amount of light rays in the direction of the thickness of the liquid film occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a culturing method for efficiently culturing photosynthetic organisms, and in particular, culturing microalgae in a liquid film of a culture solution formed on the surface of a liquid film forming plate to achieve extremely high culture. It relates to a technique for culturing at a high speed.

[0002]

2. Description of the Related Art Conventionally, a large amount of photosynthetic organisms such as chlorella and spirulina have been cultivated, and useful substances such as sugars, fermentation substrates, proteins, unsaturated fatty acids and pigments have been produced from the cultivated photosynthetic organisms, or photosynthetic organisms have been used. Wastewater treatment was performed. In addition, as the problem of global warming due to the large amount of carbon dioxide emission is highlighted, research and development of exhaust gas treatment technology for absorbing and assimilating carbon dioxide in exhaust gas by photosynthetic organisms is underway. In the production of useful substances, wastewater, and exhaust gas purification using such photosynthetic organisms, how to efficiently supply light and carbon dioxide to the photosynthetic organisms in the culture solution in order to increase the culture efficiency Is important.

Conventionally, in the culture of chlorella or the like, as a method of supplying light into the culture tank, a method of irradiating light into the culture tank by immersing a large number of optical fibers or light diffusion rods in the culture tank, photosynthesis There are a method of irradiating sunlight and light of an artificial light source from the outside by stirring a culture solution containing organisms, and a method of irradiating light by installing a light source in a culture tank. Further, as a method of forcibly supplying a gas containing carbon dioxide into the culture solution, there is a method of forcibly ventilating the gas from the lower part in the culture tank.

[0004]

However, among the above-mentioned methods for supplying light, when a method of immersing an optical fiber or a light diffusing rod and when a light source is installed in a tank, the propagated photosynthetic organisms are converted into an optical fiber. There has been a problem that the irradiation efficiency is reduced by adhering to the surface or the surface of the rod. Also,
The method of irradiating sunlight or light from an artificial light source from the outside of the culture tank requires that the culture solution be constantly stirred in order to make the light conditions uniform, and this stirring has the drawback of damaging cultured organisms, and There is a problem that high energy is required for culturing. Further, in the method of forcibly ventilating a gas containing carbon dioxide from the lower part of the culture tank, there is a problem that the photosynthetic organisms that have proliferated adhere to the vent tube and the vent tube is likely to be clogged, and high energy is required for venting.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a culture method capable of efficiently supplying light and carbon dioxide in culturing a photosynthetic organism and culturing the photosynthetic organism extremely efficiently.

[0006]

In order to solve the above-mentioned problems, the present invention allows a culture solution containing a photosynthetic organism to flow down in the form of a liquid film along the surface of a liquid film forming plate, and the liquid film and the dioxide. This is a method of culturing a photosynthetic organism by bringing the liquid film into contact with a gas containing carbon and irradiating the liquid film with light, and is characterized by using Anacystis nidulans as the photosynthetic organism. In another aspect of the present invention, a plurality of liquid film forming plates are laminated and arranged so that the upstream end of each plate is adjacent to the downstream end of the upper plate and the downstream end is adjacent to the upstream end of the lower plate. The feature is that the culture solution is sequentially flown down onto these liquid film forming plates. Furthermore, in these culturing methods, in order to irradiate the liquid film forming plate with light, the light of artificial light source or sunlight is guided through the optical fiber to irradiate the liquid film forming plate with the light, or the optical fiber is formed into a liquid film. Irradiation may be performed from the surface of the liquid film forming plate by connecting to the plate. Air or carbon dioxide-containing exhaust gas is used as the gas containing carbon dioxide. Further, it is desirable to recover a part of the photosynthetic organisms from the culture solution that has flowed down the liquid film forming plate, and circulate this culture liquid to the upstream end of the liquid film forming plate to carry out the culture.

[0007]

In the method for culturing a photosynthetic organism of the present invention, a liquid film of a culture solution containing a photosynthetic organism is formed on a liquid film forming plate, and the light from the light source and the dioxide from the surrounding gas phase are formed in this liquid film. It is used to cultivate photosynthetic organisms by supplying it while supplying carbon, and the thickness of the liquid film to be formed can be easily controlled by appropriately adjusting the flow rate of the culture liquid and the inclination angle of the liquid film forming plate. be able to. When culturing photosynthetic organisms in this liquid film, it is possible to irradiate light in the thickness direction of the liquid film because the liquid film is thin. By doing so, the contact area with the gas phase increases, and the carbon dioxide contained in the surrounding gas phase is easily taken into the liquid film.

Further, as a photosynthetic organism, microscopic algae, Anacystis nidulans, is used to carry out the liquid film flow-down culture on the liquid film forming plate, so that the liquid culture liquid is crushed by a circulation pump or the like. Photosynthesis can be carried out with extremely high efficiency without causing precipitation and adhesion on the liquid film forming plate to reduce the activity. That is, when the above-mentioned liquid film flow-down culture is performed using Chlorella or Spirulina, it is highly efficient because it is crushed by a liquid-feeding pump or the adhesion of precipitates on the liquid film-forming plate is remarkable and the activity decreases. Although it is difficult to cultivate the bacterium, the size of Anacystis nidulans used in the present invention is as small as about 1 to 2 μm, and it is crushed in the liquid film flow-down culture or precipitated on the liquid film forming plate. Even if the culture solution is flown and circulated in the form of a liquid film on the liquid film forming plate without adhering to each other, good growth is exhibited even when culturing is performed, and photosynthesis can be performed with extremely high efficiency.

[0009]

EXAMPLES An example of the method for culturing a photosynthetic organism of the present invention will be described below with reference to the drawings. In the culture method of the present invention, as a photosynthetic organism, Anacystis nidulans ( Ana
cystis nidulans ), and the culture solution containing it is allowed to flow down in the form of a liquid film along the surface of the liquid film forming plate, and the liquid film is brought into contact with a gas containing carbon dioxide, and the liquid film is exposed to light. Irradiate and culture. The Anacystis nidulans used in the present invention is a fine unicellular alga of the cyanobacteria (about 1-2 μm in size), and is known as Anacystis nidulans IAM M6. The Anacystis nidulans has the characteristics that they are small and are difficult to adhere to each other even if they grow. Also, Chlorella,
Compared to other photosynthetic organisms such as Spirulina, it grows faster,
The photosynthetic ability (carbonic acid assimilation ability) is strong, and the amount of carbon dioxide immobilized per unit alga weight is larger than that of other photosynthetic organisms.
Furthermore, the optimum growth temperature is around room temperature (about 25 to 30 ° C.), and the pH range in which growth is possible is wide.
Since it can grow at about 8, it has a wide range of culture conditions and is easy to culture. In addition, it is possible to grow in a completely inorganic nutrient medium that does not use organic nutrients such as vitamins, and an inexpensive culture medium can be used.

FIGS. 1 and 2 show an example of a culture device suitable for carrying out the method for culturing a photosynthetic organism of the present invention. This culture device 1 comprises a plurality of liquid film forming plates 2 ...
The culture section 3 in which the upstream end of each plate 2 is adjacent to the downstream end of the upper plate 2 and the downstream end is adjacent to the upstream end of the lower plate 2 and the upper end of the culture section 3 A culture solution supply means 5 for supplying a culture solution 4 containing a photosynthetic organism, a light source 7 for irradiating a liquid film 6 formed on the culture section 3 with light, a container 8 for containing this culture section 3, and this container And a gas supply means 10 for supplying a gas containing air or carbon dioxide into the container 8 from a gas supply port 9 provided in 8.

Each liquid film forming plate 2 of the culture section 3
Are arranged with an inclination of 30 degrees or less, preferably about 5 to 15 degrees. Even when the liquid film forming plate 2 is almost horizontal, when the culture solution 4 is supplied, the culture solution 4 can be caused to flow down by the supply pressure. The number of stacked layers of the liquid film forming plate 2 in the culture section 3 is not particularly limited, and may be one or more.

The culture solution supply means 5 is a culture solution adjusting tank 1
1, a liquid feed line 12 extending from the culture liquid adjusting tank 11 to the vicinity of the upstream end of the liquid film forming plate 3 through the upper portion of the container 8, a liquid feed pump 13 interposed in the liquid feed line 12, and a bottom portion of the container 8. And a recovery line 15 that connects the liquid discharge port 14 provided to the culture solution adjusting tank 11 and the liquid supply line 12 for supplying the culture solution 4 containing the photosynthetic organisms in the culture solution adjusting tank 11.
It is configured to be pressure-fed by the liquid feed pump 13 through the liquid feed line 12 and to be supplied from the liquid feed unit 16 at the end of the liquid feed line 12 to the upstream end of the culture unit 3 at a predetermined flow rate. The supply flow rate of the culture solution 4 can be easily adjusted by the liquid delivery pump 13, and the supply flow rate is appropriately set depending on the area of the culture section 3, the inclination degree of the liquid film forming plate 2, and the like. For example, when the plate 2 of about 1 m ² is inclined at an inclination of 5 to 10 degrees and a liquid film having a thickness of about 1 mm to 5 mm is formed on the surface thereof, the culture solution 4 is ^added from 50 liter · h ⁻¹ to 500. It is desirable to supply at a flow rate of about liter · h ⁻¹ .

The culture line adjusting tank 11 has a harvest line 1
A harvesting device 18 is connected via 7 and a part of the culture solution 4 flowing down through the recovery line 15 is sent to the harvesting device 18 to separate (harvest) photosynthetic organisms in the culture solution 4. . As the harvesting device 18, a filtering tank, a precipitation tank, a centrifugal tank, or the like is used according to the size of the photosynthetic organism. The culture solution from which the photosynthetic organism has been separated may be returned to the culture solution adjusting tank 11 through another line. The temperature of the culture solution 4 is adjusted by installing a heat exchanger, a heater, a freezer, or the like from the culture section 3 to all or part of the culture solution supply means 5. The culture temperature is adjusted to a temperature suitable for culturing the target organism. The shape of the liquid supply section 16 for supplying the culture solution 4 containing the photosynthetic organism to the upstream end of the culture section 3 is appropriately selected from a single tube, a branch tube, a manifold and the like.

The light source 7 is composed of a xenon lamp 19 and a light guide 20 for guiding the light to the peripheral edge of each liquid film forming plate 2. The light guide 20 is formed by bundling a large number of optical fibers. In this example, the liquid film forming plate 2 is formed of a transparent plate material or a plate material having high reflectance, and the light guide 20
The emission ends of a large number of optical fibers are arranged on the periphery of the liquid film forming plate 2, and the light guided through the light guide 20 is applied to the liquid film forming plate 2.
It is configured to radiate from the surface of. The configuration of the light source 7 is not limited to this example, and the light guide 20
Instead of connecting the liquid film forming plate 2 to the liquid film forming plate 2, the liquid film 6 may be irradiated with light by arranging the emission end above each liquid film forming plate 2. Further, instead of the xenon lamp 19, another light source, for example, sunlight may be guided by the light guide 20 and irradiated. Further, a light source such as a fluorescent lamp is used for each liquid film forming plate 2 without using a light guide.
It may be arranged on the upper part of.

The gas supply means 10 for supplying gas into the container 8 is a gas supply port 9 at the bottom of the container 8 for supplying exhaust gas containing air or carbon dioxide or the like through the gas supply line 10a.
Is supplied at a predetermined flow rate. The exhaust gas used here is one from which harmful components such as sulfur oxides and hydrogen chloride gas have been removed in advance, and LNG combustion exhaust gas containing a small amount of these harmful components is preferable. The gas supplied into the container 8 is released to the outside from the gas discharge port 21 at the upper end of the container 8. The released gas is returned to the gas supply means 10 through the gas return line 22 as needed. It is also possible to circulate.

In order to cultivate Anacystis nidulans using the culturing apparatus 1, purely cultivated Anacystis nidulans is mixed with the culture solution 4 and placed in the culture solution adjusting tank 11, and the liquid feeding pump 13 is driven. Let the liquid transfer line 1
The culture solution 4 is supplied from the upstream end of the culture section 3 through 2 and flows down in the form of a liquid film, and at the same time, each liquid film forming plate 2 is irradiated with light from a light source 7 through a light guide 20 to hit the liquid film 6, and A gas containing air or carbon dioxide is supplied into the container 8 from the gas supply port 9. The culture solution 4 supplied onto the liquid film forming plate 2
The photosynthetic organisms contained therein receive the light energy from the light source 7 while flowing down the liquid film forming plate 2 one by one, and the container 8
It grows while performing photosynthesis using carbon dioxide in the gas phase therein and water in the culture medium as raw materials. Liquid film 6 of this culture solution 4
Since it is as thin as 1 to 5 mm, it is possible to irradiate light in the thickness direction of the liquid film, and the contact area with the gas phase is increased by allowing the culture solution to flow down in the form of a liquid film. However, carbon dioxide contained in the surrounding gas phase is easily taken into the liquid film.

The culture solution 4 flowing down to the downstream end of the liquid film forming plate 2 at the lowermost stage of the culture section 3 has a liquid outlet 14 at the bottom of the container 8.
To the outside, and enters the culture solution adjusting tank 11 through the recovery line 15. And this culture solution 4 is a liquid transfer line 1
It is supplied again to the upstream end of the liquid film forming plate 2 at the uppermost stage of the culturing section 3 through 2 and is circulated to continuously cultivate the photosynthetic organism. When the concentration of the photosynthetic organism in the culture solution 4 has increased to a certain extent, a part of the culture solution in the culture solution adjusting tank 11 is sent to the harvesting device 18 through the harvesting line 17, and the culture solution 4
The photosynthetic organisms in the medium are collected, and a newly prepared culture liquid or a culture liquid in which the photosynthetic organisms are separated is used as a culture liquid adjusting tank 1
1 and replenish the culture solution 4.

This culture apparatus 1 forms a liquid film 6 of a culture solution 4 containing a photosynthetic organism on a liquid film forming plate 2, and in this liquid film 6 light from a light source 7 and from the surrounding gas phase are formed. The photosynthetic organism is cultivated by flowing it while supplying carbon dioxide, and the thickness of the liquid film 6 formed by appropriately adjusting the flow rate of the culture liquid 4 and the inclination angle of the liquid film forming plate 2. It can be controlled easily. When culturing a photosynthetic organism in the liquid film 6 as described above, since the liquid film is thin, it is possible to irradiate light in the entire thickness direction of the liquid film. Since the contact area with the gas phase is increased by letting it flow down in the form of a gas and carbon dioxide contained in the surrounding gas phase can be easily taken into the liquid film, stirring of the culture solution 4 can be omitted, Moreover, the supply efficiency of light and carbon dioxide is improved, and the culture efficiency per installation area can be significantly improved. Further, since the stirring of the culture solution 4 can be omitted, it is possible to eliminate the inconvenience that the photosynthetic organisms are damaged by the stirring, and further it is possible to reduce the energy required for operation. Furthermore, as a photosynthetic organism, Anacystis nidulans, which is a microalgae, is used to carry out liquid film flow-down culturing on the liquid film forming plate, so that the liquid culture liquid is crushed by a circulation pump, etc. It is possible to perform photosynthesis with extremely high efficiency without causing the activity to be deteriorated due to the precipitation and adhesion on the plate. Hereinafter, the effects of the present invention will be clarified by experimental examples.

(Experimental example) A prototype of the culture device shown in FIGS. 1 and 2 was produced, and Anacystis nidulans, Chlorella and Spirulina were cultured, and their growth states were compared. Four liquid film forming plates each having a square shape with a side of 50 cm were used, and they were arranged as shown in FIG. Further, the light source 7 is a xenon lamp light source, and the light from the light source is guided to the periphery of each liquid film forming plate by the light guide 20, and the light is irradiated from the surface through each liquid film forming plate 2. As the liquid film forming plate 2, a glass plate having a high reflectance plate (stainless steel plate) bonded to the lower surface was used. A liquid culture medium containing any of Anacystis nidulans, Chlorella and Spirulina is flown down to this liquid film forming plate, and the flow rate of the circulation pump is set so that the thickness of the liquid film is about 2 to 3 mm, and the growth component is increased. Each alga was cultivated for about 1 month while collecting and appropriately supplementing the medium. Table 1 shows the culture conditions of each algae and the growth rate of the algae (dry matter growth rate).

[0020]

[Table 1]

As a result of this experiment, Spirulina was killed on the 10th day of culturing because it was crushed by a liquid feed pump. Although chlorella could be cultivated for some time, when the inclination of the liquid film forming plate was less than 15 °, precipitation on the liquid film forming plate was remarkable, and an extremely low growth rate was observed. When Anacystis nidulans was used, a high growth rate was exhibited without cell disruption by a liquid delivery pump or precipitation on the liquid film forming plate.

[0022]

As described above, the apparatus for cultivating photosynthetic organisms according to the present invention forms a liquid film of a culture solution containing photosynthetic organisms on a liquid film forming plate, and a light from a light source is formed in the liquid film. Carbon dioxide from the surrounding gas phase is supplied while flowing down to cultivate a photosynthetic organism, and a liquid film formed by appropriately adjusting the flow rate of the culture solution and the inclination angle of the liquid film forming plate. The thickness of can be easily controlled.
When culturing a photosynthetic organism in a liquid film in this way, it is possible to irradiate light in the entire thickness direction of the liquid film because the liquid film is thin. The contact area with the gas phase is increased by letting the solution flow down, and the carbon dioxide contained in the surrounding gas phase can be easily taken into the liquid film, so that the stirring of the culture solution can be omitted and the Also, the supply efficiency of carbon dioxide is improved, and the culture efficiency per installation area can be significantly improved. Further, since the stirring of the culture solution can be omitted, it is possible to eliminate the inconvenience that the photosynthetic organisms are damaged by stirring, and it is possible to reduce the energy required for operation. Furthermore, as a photosynthetic organism, Anacystis nidulans, which is a microalgae, is used to carry out liquid film flow-down culturing on the liquid film forming plate, so that the liquid culture liquid is crushed by a circulation pump, etc. It is possible to perform photosynthesis with extremely high efficiency without causing the activity to be deteriorated due to the precipitation and adhesion on the plate.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a culture device suitable for a method for culturing a photosynthetic organism of the present invention.

FIG. 2 is a perspective view showing a partial cross-section of a main part of the same culture apparatus.

[Explanation of symbols]

1 ... Incubator, 2 ... Liquid film forming plate, 3 ... Incubator, 4
...... Culture fluid, 5 ...... Culture fluid supply means, 6 ...... Liquid film, 7 ...
... light source, 8 ... container, 9 ... gas supply port, 10 ... gas supply means, 11 ... culture solution adjusting tank, 12 ... liquid supply line, 13 ... liquid supply pump, 14 ... liquid discharge port , 15 ……
Recovery line, 16 ... Liquid supply section, 17 ... Harvest line,
18 ... Harvesting device, 19 ... Xenon lamp, 20 ...
Light guide, 21 ... Gas outlet, 22 ... Gas return line.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area C12N 1/00 ZAB Q 8828-4B // C12M 1/00 E (C12N 1/12 C12R 1:89 (72) Inventor Kazuhiko Oniyama 2-8-11 Nishi-Shimbashi, Minato-ku, Tokyo Inside Institute for Global Environmental Technology

Claims (5)

[Claims] 1. A culture solution containing a photosynthetic organism is caused to flow down in a liquid film shape along the surface of a liquid film forming plate, and the liquid film is brought into contact with a gas containing carbon dioxide, and light is applied to the liquid film. A method for culturing a photosynthetic organism by irradiating, which comprises using Anacystis nidulans as the photosynthetic organism. 2. The method for culturing a photosynthetic organism according to claim 1, wherein a plurality of liquid film forming plates are provided, the upstream end of each plate is adjacent to the downstream end of the upper plate, and the downstream end is the upstream end of the lower plate. A method for culturing a photosynthetic organism, which comprises arranging them so that they are adjacent to each other and sequentially flowing the culture solution onto these liquid film forming plates. 3. The method for culturing a photosynthetic organism according to claim 1 or 2, wherein light from an artificial light source or sunlight is introduced through an optical fiber to irradiate the liquid film forming plate, or the optical fiber is connected to the liquid film forming plate. And irradiating from the surface of the liquid film-forming plate. 4. The method for culturing a photosynthetic organism according to claim 1, wherein the carbon dioxide-containing gas is air or carbon dioxide-containing exhaust gas. 5. The method for cultivating a photosynthetic organism according to claim 1, wherein a part of the photosynthetic organism is recovered from the culture solution flowing down the liquid film forming plate, and the culture solution is formed into a liquid film. A method for culturing a photosynthetic organism, which comprises culturing by circulating it at an upstream end of a plate.