JP2017000124A - Algae culture method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cultivating algae in a large quantity at a low price in the field without requiring a large-scale civil engineering work or constructing a new structure; It is an object of the present invention to provide a culture method in which problems such as occurrence of culture trouble are suppressed. In culturing algae; digging an elongated groove 2 in the ground surface 1; in the groove 2, an elongated tube 3 made of a translucent soft film is in contact with the longitudinal direction of the groove 2. The algae and the culture solution are enclosed in the tube 3; a gas containing carbon dioxide is taken into the tube 3 during or after the enclosure, and the internal pressure of the tube 3 is enclosed. And culturing the tube 3 by expanding and deforming the tube 3 above the atmospheric pressure; [Selection] Figure 1

Description

The present invention relates to a method for culturing algae, and more particularly to a method for culturing algae efficiently in an outdoor field.

Since algae produce useful substances such as vitamins and amino acids, techniques for culturing them in large quantities have been studied, and in recent years, they have attracted attention as new biomass resources.

There are light, temperature, nutrients, and carbon dioxide as the environment or equipment necessary for the algae culture device, and the open type open to the atmosphere and the closed type are known as the culture device in the outdoor field. ing.

Among them, the open culture device is difficult to produce unless it is a species that grows in a special environment such as a strong alkali, because it is a problem of mixing different types of substances beyond the control of the growth environment such as light, temperature, and nutrients. .

On the other hand, the closed type culture apparatus does not cause the above-mentioned problems in the open type culture apparatus, but the limit water temperature (liquid temperature) of the algal culture is about 42 ° C., and the liquid temperature is low in summer. There is a problem that the culture is troubled due to the excessive rise.

Therefore, for example, in a closed culture device having a transparent dome shape or the like, an air or carbon dioxide gas introduction member, a culture solution discharge member, and a watering member for spraying cooling water are provided. It has been proposed (see Patent Document 1).
According to this culture apparatus, the temperature of the culture solution can be adjusted by the cooling water.

However, in the case of this apparatus, in addition to a watering member for sprinkling cooling water, a watering receiver for receiving watering is required, so that the culture apparatus becomes considerably large.
In addition, whether it is a closed type or an open type, the conventional outdoor cultivation apparatus requires large-scale civil engineering work or construction of a new structure, which requires a large initial investment. In addition, it has a drawback that it has a low affinity with agriculture, such as being difficult to return it to farmland.

WO99 / 50384 Publication

The present invention eliminates the above-mentioned conventional problems and provides a method for cultivating algae in a large amount at an outdoor field without the need for large-scale civil engineering work or construction of a new structure. It is intended to do.
Another object of the present invention is to provide a culture method in which the problem that the temperature of the solution rises excessively in the summer and a culture trouble occurs is suppressed.

That is, the present invention provides the following (1) to (5).
(1): In culturing algae;
Digging an elongated groove in the ground surface;
In the groove, an elongated tube made of a translucent soft film is laid such that its longitudinal direction is in contact with the longitudinal direction of the groove;
Enclosing algae and a culture solution in the tube;
During or after the encapsulation, a gas containing carbon dioxide is taken into the tube, and the internal pressure of the tube is increased from the atmospheric pressure to expand and deform the tube, and culture is performed;
The present invention relates to a method for culturing algae.

(2): The method for culturing algae according to (1) above, wherein the cross-sectional shape of the groove is substantially semicircular or semi-elliptical.

(3): The method for culturing algae according to (1) or (2) above, wherein the algae is an oil-producing alga or Chlamydomonas that performs photosynthesis.

(4): The method for culturing algae according to any one of (1) to (3), wherein the translucent soft film is a polyethylene film.

(5): The method for culturing algae according to any one of (1) to (4) above, wherein the gas containing carbon dioxide taken into the tube is air.

ADVANTAGE OF THE INVENTION According to this invention, it is not necessary to require large-scale civil engineering work or to construct a new structure, and a method for culturing and proliferating algae in large quantities at an outdoor field is provided.
In addition, according to the present invention, there is provided a culture method that can suppress an increase in the liquid temperature in the summer and suppresses problems such as the occurrence of a culture trouble due to an excessive increase in the temperature of the liquid in the summer. The
Furthermore, according to the present invention, since the water temperature decrease can be suppressed at low temperatures in winter, the outdoor growth period can be expanded in combination with the suppression of the increase in liquid temperature in summer.
In the method of the present invention, an elongated groove is dug in the ground surface using a vertical machine or the like, and an elongated tube made of a translucent soft film is laid in the groove to culture algae. Therefore, it is possible to culture using idle farmland.
Therefore, it is expected that algae can be cultured outdoors even more inexpensively.

It is a photograph image figure which shows the state which is performing the method of this invention. It is a graph which shows the light absorbency of 660 nm measured as a parameter | index of the amount of algae in a culture solution. It is a graph which shows an example of the liquid temperature change at the time of the summer high temperature in Example 1 with the change of air temperature. It is a graph which shows an example of the liquid temperature change at the time of the low temperature of winter in Example 1 with the change of air temperature.

The present invention will be described below with reference to the drawings. FIG. 1 is a photographic image showing an example of a state in which the method of the present invention is performed. In FIG. 1, reference numeral 1 denotes the ground surface, reference numeral 2 denotes a groove, and reference numeral 3 denotes an elongated tube.

The present invention relates to a method for culturing algae, and when cultivating algae; digging an elongated groove 2 in the ground surface 1; an elongated tube 3 made of a translucent soft film in the groove 2; Laying so that the longitudinal direction is in contact with the longitudinal direction of the groove 2; enclosing the algae and the culture solution in the tube 3; carbon dioxide in the tube 3 during or after the enclosing The gas is contained, and the culture is performed by raising the internal pressure of the tube 3 above atmospheric pressure and expanding and deforming the tube 3.

In the present invention, first, an elongated groove 2 is dug in a ground surface 1 such as a farm field. It can be said that this groove is a “groove-shaped dent”.
The groove 2 preferably has a substantially semicircular or semi-elliptical cross-sectional shape.
Here, the substantially semicircular shape to the substantially semielliptical shape includes a shape between a substantially semicircular shape and a substantially semielliptical shape.
Here, when the cross-sectional shape of the groove 2 is not substantially semicircular or semi-elliptical, and the cross-sectional shape of the groove 2 is rectangular, for example, the elongated shape described later in such a groove 2 is used. Even if the tube 3 is laid and the internal pressure of the tube 3 is increased above the atmospheric pressure so that the tube 3 is expanded and deformed so that the contact portion between the tube 3 and the groove 2 is brought into close contact, the groove is unavoidable. A gap is likely to form at the corner between the tube 2 and the elongated tube 3, and rainwater accumulates in this gap when it rains, and the temperature of the liquid rises too much in the summer, causing culture problems. There is a risk.

About the depth of the groove | channel 2, since it is a culture | cultivation of algae and it is necessary for light to permeate | transmit and reach | attain to the deepest position, it is preferable to set it as less than 500 mm (0.5 m) at the deepest.
Further, the width of the groove 2 may be appropriately determined in consideration of the size of the elongated tube 3 laid in the groove 2, but is generally about 400 mm (0.4 m).
Such molding of the groove 2 can be performed by using, for example, a treadmill, a trench mower, a grooving machine, a cultivating board, or the like.

In the present invention, the elongated tube 3 is laid in such a groove 2 so that the longitudinal direction thereof is in contact with the longitudinal direction of the groove 2. The elongate tube 3 can be laid by using, for example, a multi-film laying machine called a “marcher” for the tube wound in a roll shape. Moreover, it can also lay by using the winder etc. and pulling out the tube 3 currently wound by the winder.
The size of the elongated tube 3 is not particularly limited, but may be selected in consideration of the amount of algae cultured, the depth of the groove 2 of less than 500 mm, and the like.

Here, the elongated tube 3 can be processed (heat-sealed) for enclosing the culture solution and installing a gas intake port containing carbon dioxide; when the culture solution is added, it is deformed by its own weight, and the ground surface 1 (soil Softness to adhere to the surface); transparency to transmit sunlight; contact with the ground surface 1 (soil surface) and thin enough to transfer heat; outdoor weather conditions throughout the culture period It is necessary to have such a strength that it can withstand the above; therefore, a film made of a light-transmitting soft film is used, and more specifically, a polyethylene film, a polyvinyl chloride film, ethylene- One kind selected from vinyl acetate copolymer films is preferable, and a polyethylene film is most preferably used.
The thickness of the translucent soft film is about 0.05 to 0.2 mm, generally about 0.1 mm, but is not limited thereto.

Then, the algae and the culture solution are placed (enclosed) in the elongated tube 3.
Here, the algae is not particularly limited as long as it is an algae that performs photosynthesis, but oil-producing algae that perform photosynthesis or Chlamydomonas reinhardtii (Japanese name: Conamidrum) are preferable.
Examples of oil-producing algae that perform photosynthesis include algae belonging to the genus Botryococcus, and more specifically, Botryococcus braunii having high oil-producing ability is preferably used. .

Any culture medium may be used as long as it can be used for culturing algae. In addition to liquid culture media for algae such as C medium and AF-6 medium, liquid fertilizer and the like can also be used.

In addition, in the elongated tube 3, it is necessary to put the culture solution to such an extent that a gap is formed so that a gas containing carbon dioxide can be taken in. Usually, the culture solution is an elongated tube. It should be about half of the cross section of 3.
When the culture solution is sealed in the elongated tube 3 laid in the groove 2, the elongated tube 3 is fixed in the groove 2 by its own weight.
For this reason, the elongate tube 3 does not require a special fixture and does not require wind countermeasures.

When encapsulating the algae and the culture solution in the elongated tube 3 or after enclosing them, a gas containing carbon dioxide is taken into the elongated tube 3, and the inside of the elongated tube 3. The elongate tube 3 is expanded and deformed by increasing the pressure above atmospheric pressure, thereby bringing the contact portion between the elongate tube 3 and the groove 2 into close contact (so that there is no gap between them).

The gas containing carbon dioxide can be taken into the elongated tube 3 by installing a gas inlet containing carbon dioxide in the elongated tube 3 or the like.
A gas containing carbon dioxide is taken into the elongated tube 3 and used for algae growth. As the gas containing carbon dioxide, carbon dioxide alone, air, or a mixture of carbon dioxide and air to increase the concentration of carbon dioxide can be used. Therefore, it is most preferable to use air.

An aspirator can be used in addition to a cylinder or an air pump to take in and enclose gas containing carbon dioxide into the elongated tube 3, but the air pump is the most convenient and most preferable.
The internal pressure can be adjusted by attaching a vent filter, preferably a HEPA vent filter, to the elongated tube 3. In particular, by attaching a HEPA vent filter, contamination other than the target strain can be avoided.
In this way, by attaching the vent filter to the elongated tube 3, it is possible to ensure airtightness while ensuring ventilation and adjusting internal pressure.

In this manner, the gas containing carbon dioxide is taken into the elongated tube 3 and the elongated tube 3 is expanded and deformed by raising the internal pressure of the elongated tube 3 to be higher than the atmospheric pressure.
As a result, the cross section of the elongated tube 3 is substantially elliptical.
In this way, when the elongated tube 3 is expanded and deformed by raising the internal pressure of the elongated tube 3 to be higher than the atmospheric pressure, water can be accumulated on the elongated tube 3 even in the case of rain or snowfall. There is no. In addition, sand dust or the like is not easily collected, and is washed every time it rains or snows, and can be kept clean.
In this sense, the elongated tube 3 is expanded and deformed to such an extent that water cannot be accumulated on the elongated tube 3 when it rains, and the elongated tube 3 is at atmospheric pressure. It will be to the extent that does not burst.

Furthermore, the gas containing carbon dioxide is taken into the elongated tube 3, and the internal pressure of the elongated tube 3 is increased from the atmospheric pressure to expand and deform the elongated tube 3. Although the cross section is substantially elliptical, the elongated tube 3 is fixed in the groove 2 by its own weight, so that the elongated tube 3 and the groove 2 are so dense that there is no gap between them. Contact. As a result, underground temperature (ground temperature) can be used, and contact heat exchange can be performed between the inside of the groove 2 close to the ground temperature and the elongated tube 3. As a result, there is a feature that it is possible to suppress an increase in the temperature of the culture solution particularly in summer.

That is, in the summer when the temperature is high, the culture solution or the like in the elongated tube 3 is cooled by the influence of a stable ground temperature lower than the temperature and efficiently suppresses the rise in the water temperature (liquid temperature). Can do. At this time, in particular, the amount of the culture solution inside the elongated tube 3 is set to about half of the cross section of the elongated tube 3 so that the level of the culture solution becomes the ground surface 1 or less as a whole. A further increase in water temperature (liquid temperature) can be suppressed, which is preferable.
On the other hand, in the winter when the temperature is low, the culture solution in the elongated tube 3 is affected by the stable ground temperature higher than the temperature, and can suppress a decrease in water temperature (liquid temperature), particularly at night. The water temperature (liquid temperature) can be maintained higher.

In this way, the elongated tube 3 is expanded and deformed, and the elongated tube 3 and the groove 2 are brought into close contact with each other so that there is no gap between them, and the algae is cultured.
At this time, as described above, it is preferable to perform the culture so that the level of the culture solution in the elongated tube 3 is not more than the ground surface as a whole.
As a result, it is not necessary to perform large-scale civil engineering work or construct a new structure, and algae can be cultured and propagated in large quantities at low cost in the field.
In the present invention, algae can be cultured in large quantities using outdoor sunlight, particularly summer sunlight.
In addition, according to the present invention, the problem that the temperature of the solution rises too much in the summer and a culture trouble occurs can be solved.
Furthermore, it is possible to suppress a decrease in liquid temperature at low temperatures in winter.
Moreover, since the method of the present invention is a closed system, there is no risk of contamination of microorganisms from the field, and a large amount of single algae can be cultured.

The present invention basically can adjust the liquid temperature to some extent without actively adjusting the temperature, and can suppress an increase in the liquid temperature especially in summer. In order to prevent the temperature of the culture solution from becoming too high in the summer, it can be performed in combination with a temperature lowering means as necessary. Specifically, for example, drip is applied to the surrounding soil where the elongated tube 3 is laid, or water is sprayed on the surface of the elongated tube 3.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, the scope of the present invention is not limited by these.

Test example 1 (laying of tube and culture test of algae)
(1) Laying the tube As a material for the algae culture tank, an elongated polyethylene tube 3 (made of polyethylene film; thickness 0.1 mm × diameter 0.4 m × length 5 m) which was molded and wound into a roll was prepared.

Tsukuba City, Ibaraki Prefecture, after planting the field (field) 1 (A groove 2 in which the elongated polyethylene tube 3 is just inserted; specifically, a groove having a width of 0.4 m and a depth of 0.2 m) is dug, and the groove 2 is molded as described above and wound into a roll. The elongated polyethylene tube 3 is pulled out from the winder installed at the end of the elongated groove 2 in the longitudinal direction of the groove 2 and cut according to the length of the groove 2 to obtain an elongated polyethylene tube. 3 was laid such that the longitudinal direction of 3 was in contact with the longitudinal direction of the groove 2.

After laying, one end of the elongated polyethylene tube 3 is heat-sealed and sealed, and the other end is provided with an introduction port that serves as an introduction port for algae and a culture solution and also serves as a gas (gas) introduction port. A filter was attached to the end of the exhaust tube.
That is, after laying, one end of the tube 3 is heat-sealed and sealed, and the other end is about 0.5 m from the end of the polyethylene tube 3 and a screw-in inlet is provided from the inside and outside of the tube 3. After attaching 3 together with packing so as to sandwich 3, the end was heat-sealed and sealed.
Inside the lid of the inlet, an air pump tube for intake with an air stone for supplying oxygen, an exhaust tube with a HEPA vent filter, and a temperature sensor were attached, respectively.

(2) Culture of algae After installation, open the lid of the inlet, and the culture solution (horticulture fertilizer; fertilizer component NPK = 6-10-5) and algae (Tsukuba City, Ibaraki Prefecture) in the tube 3 150 L of subcultured algae collected in a water field (mainly Chlamydomonas) was injected, and the lid was closed when a predetermined amount was reached. By operating the air pump, air bubbles were generated in the culture medium from the air stone, and air entered the tube 3, and the tube 3 swelled and adhered closely to the groove.
In this way, air is introduced into the tube 3, the internal pressure of the tube 3 is increased above atmospheric pressure, the tube 3 is expanded and deformed, and the tube 3 and the groove 2 are removed so that there is no gap between them. The algae were cultured in close contact with each other.
At this time, the culture was performed such that the level of the culture solution in the elongated tube 3 was not more than the ground surface as a whole.

FIG. 1 is a photographic image showing a state in which the method of the present invention is performed in this way.
According to FIG. 1, it can be seen that by enclosing a culture solution or air in an elongated polyethylene tube 3, it is fixed in close contact with the groove 2 by its own weight in accordance with the shape of the groove 2.
That is, in the method of the present invention, the elongate tube 3 has a fine surface surface 1 by enclosing the culture solution and gas (gas) in the elongate tube 3 and increasing the internal pressure above atmospheric pressure. The shape was maintained while adhering to the unevenness by its own weight, and it was stable against liquid movement and strong wind in the elongated tube 3.

As described above, as a result of culturing by the method of the present invention, algae grew well.
FIG. 2 shows the change over time in the absorbance at 660 nm (OD660) measured as an indicator of the amount of algae in the culture because it has a high correlation with the chlorophyll content of algae.
As shown in FIG. 2, the absorbance clearly increased with the lapse of the culture time, and according to the method of the present invention, it was confirmed that the algae grew and the algae amount increased.
The amount of increase in algae at the end of the culture according to the method of the present invention was determined to be 0.91 g / L · 7 days.

As for the temperature during the culture period, the minimum temperature was 12.5 ° C, and the maximum temperature was 29.1 ° C. The water temperature in the elongated polyethylene tube 3 rose to a maximum of 37.4 ° C. and averaged 27.2 ° C.

Test Example 2 (Investigation test of tube durability and liquid temperature change)
The tube was laid in the same manner as in Test Example 1, and the durability and liquid temperature change of the tube were examined (invention zone).
The test was conducted from the end of June 2013 to March 1, 2014.
During this time, the accumulated precipitation was 910 mm, but even during the rain, there was almost no water pool on the surface of the elongated polyethylene tube 3 in the present invention zone.
In addition, the elongated polyethylene tube 3 maintained its shape even at the end of the test.

For comparison, in the present invention section, the same process as in the present invention section is performed except that the elongated polyethylene tube 3 is laid on the ground surface 1 of a flat field without digging the grooves 2. This was used as a comparative control.

Next, the liquid temperature change at the high temperature in summer in this test period and the liquid temperature change at the low temperature in winter were examined.
In FIG. 3, an example of the liquid temperature change at the time of high temperature in the summer in Test Example 2 is shown together with the change in the air temperature.
In FIG. 3, what is indicated by a circle is a graph showing a change in the liquid temperature in the present invention section.
Further, in FIG. 3, what is indicated by ■ is a graph showing a change in the liquid temperature in the comparative control group.

From FIG. 3, the liquid temperature during the daytime is about 41 to 42 ° C. and about 5 ° C. at the highest in the present invention zone compared to the comparative control zone that reaches about 47 ° C. in summer, and the algal culture is high. It can be seen that the rise in the liquid temperature was effectively suppressed.
Therefore, it is expected that the problem that the temperature of the solution rises too much at the high temperature in summer and causes troubles in culture will be solved.

FIG. 4 shows an example of a change in liquid temperature at a low temperature in winter together with a change in temperature.
In FIG. 4, what is indicated by a circle is a graph showing a change in the liquid temperature in the present invention section.
Further, in FIG. 4, those indicated by ■ are graphs showing the liquid temperature change in the comparative control group.

From FIG. 4, it can be seen that in the winter season, the liquid temperature at night can be maintained higher than that of the comparative control group in the present invention compared with the comparative control group. That is, it can be seen that the decrease in liquid temperature can be suppressed at low temperatures in winter.

In addition, a previous experiment dug a ditch in a paddy rice field and conducted the same experiment, but as in the field (field), the algae could grow well.
Therefore, the method of the present invention can be carried out in any domestic farmland that can be planted.

From the above results, it can be seen that according to the method of the present invention, the outdoor growth period can be extended with respect to the culture of algae.
That is, according to the method of the present invention (the present invention zone), it is affected by the soil temperature that is more stable than the air temperature, and is lower in the summer than the liquid temperature in the comparative control zone, higher in the winter, and outdoors. A long cultivatable period can be secured.

According to the method of the present invention, it is possible to produce algal biomass using idle farmland and the like, and it is possible to prepare a large-scale production system at low cost.
Therefore, the present invention is effectively used for culturing algae useful as a new biomass resource.

1: Ground surface 2: Groove 3: Elongated tube

Claims (5)

In culturing algae;
Digging an elongated groove in the ground surface;
In the groove, an elongated tube made of a translucent soft film is laid such that its longitudinal direction is in contact with the longitudinal direction of the groove;
Enclosing algae and a culture solution in the tube;
During or after the encapsulation, a gas containing carbon dioxide is taken into the tube, and the internal pressure of the tube is increased from the atmospheric pressure to expand and deform the tube, and culture is performed;
A method for culturing algae, which is characterized by the above.
The method for culturing algae according to claim 1, wherein a cross-sectional shape of the groove is a substantially semicircular shape or a substantially semielliptical shape.
The method for culturing algae according to claim 1 or 2, wherein the algae is an oil-producing alga or Chlamydomonas that performs photosynthesis.
The method for culturing algae according to claim 1, wherein the translucent soft film is a polyethylene film.
  The method for culturing algae according to any one of claims 1 to 4, wherein the gas containing carbon dioxide taken into the tube is air.

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