KR100439971B1 - Bubble column photobioreactors and methods for culturing photosynthetic microorganism using them - Google Patents

Abstract

The present invention relates to a photobioreactor capable of culturing a high concentration of photosynthetic microorganisms and a method of culturing photosynthetic microorganisms using the same, and specifically, a vertical cylindrical transparent outer column forming a chamber capable of containing a microbial culture solution; A light emitter which is installed at the center of the outer column and irradiates light energy on the front surface of the culture medium without disturbing the circulation of the culture medium; A vertical cylindrical transparent jacket separating the light emitting body from the culture solution and allowing heat exchange; A baffle plate having a transparent plate shape installed on an outer surface of the transparent jacket to form a circulation path of the culture solution; And an aeration device for causing upflow of the culture liquid by supplying gas upward from a lower end of one portion divided by the baffle plate, and a method for culturing the photosynthetic microorganism using the same. Bubble column photobioreactor is capable of circulating the culture medium without a separate stirrer, minimizes the light transmission distance into the circulating culture medium, and can transmit light energy to the maximum surface area of the culture medium, making it suitable for high concentration mass culture of photosynthetic microorganisms. Do.

Description

Bubble column photobioreactor and cultivation method of photosynthetic microorganism using the same {BUBBLE COLUMN PHOTOBIOREACTORS AND METHODS FOR CULTURING PHOTOSYNTHETIC MICROORGANISM USING THEM}

The present invention relates to a photobioreactor capable of culturing photosynthetic microorganisms at high concentration by supplying light energy necessary for photosynthesis efficiently into a culture medium and a culture method using the same.

Recently, various high value-added products derived from photosynthetic microorganisms have been developed, and various types of culture apparatuses for high concentration mass culture have been developed. In warm climates and inexpensive land, such as in the equator, outdoor cultures in the form of ponds or raceways that circulate the medium to paddle wheels are used. While the installation cost and operating cost are low, the high concentration is difficult and the possibility of contamination by other microorganisms is high, and the separation and recovery cost of the target product increases.

In order to overcome this, various types of photobioreactors suitable for high concentration and mass culture have been developed mainly in Western countries, Japan, Israel and Australia. Widely used photobioreactors include tubular photobioreactors and thin-panel photobioreactors that use sunlight as an external light source (domestic patent registration No. 10-0220310). The structure of the reactor maximizes the irradiation area exposed to sunlight and shortens the light transmission distance into the culture medium, so that narrow and long rectangular or cylindrical pipes are closely packed to form a loop, and a part of the loop is raised to form an air. It is characterized by having a structure that circulates the culture liquid through flotation.

On the other hand, in the areas where the four seasons are obviously changed in Korea or Japan, and the land cost is high, the internal illumination has a structure that can maximize the irradiation surface area per unit volume by installing a plurality of optical fibers, fluorescent lamps, and light emitting diode elements. Various types of internally radiating photobioreactors have been developed (Domestic Patent Registration No. 10-0001671).

However, the cultivation of photosynthetic microorganisms using the photobioreactor is advantageous in culturing small doses and high concentrations compared to the outdoor cultivation method, but when culturing in large quantities, it is difficult to scale up due to the expensive installation and operation costs due to the complexity of the reactor structure. It is mainly used for limited production of high value added materials. In addition, considering the domestic biotechnology-related market is narrow, and existing bioreactors are widely distributed, and many domestic workers who have abundant experience in the field of operation are considering the use of new biocultivators. It is anticipated that the development of similar types of photobioreactors will have many advantages.

The type of photobioreactor currently under development in Korea is an air-lift photobioreactor (Domestic Patent Registration No. 10-0283026) and a stirrer using a cylindrical inner conduit as a light emitter. A light-emitting turbine-type photobioreactor (a domestic patent application No. 10-20010051787) is known. On the other hand, it has the simplest structure and is suitable for cultivating a large amount of microorganisms, and is an effective supply of light energy for culturing photosynthetic microorganisms based on a bubble-column bioreactor with a large irradiation area for sunlight. The development of technology for temperature control and mixing of plants has been insufficient. In addition, it is possible to use sunlight as a method of operating a photobioreactor, and to develop a high-concentration mass culture technology of photosynthetic microorganisms capable of overcoming seasonal and day-to-day light energy supply and temperature changes.

Accordingly, the present inventors have developed a photobioreactor suitable for supplying light energy to the culture medium and controlling the temperature of the culture medium and a culture method using the same, and the photobioreactor is capable of circulating the culture medium without a separate stirrer. The light transmission distance into the circulating culture medium is minimized, and light energy can be delivered to the maximum surface area of the culture medium, thereby finding a suitable concentration for high concentration mass culture of photosynthetic microorganisms.

It is an object of the present invention to provide a photobioreactor capable of culturing photosynthetic microorganisms in high concentration and a method of culturing photosynthetic microorganisms using the same.

Figure 1a is a side view schematically showing the structure of the bottom gas injection bubble column photobioreactor of the present invention,

1B is a cross-sectional view illustrating a structure in which a light emitter and a transparent jacket are installed in the bubble column photobioreactor of FIG. 1A,

1C is a cross-sectional view illustrating a structure in which a light emitter, a transparent jacket, and a baffle plate are installed in the bubble column photobioreactor of FIG. 1A.

FIG. 1D is a cross-sectional view illustrating a structure in which a light emitter, a baffle plate, and an internal heat exchanger are installed in the bubble column photobioreactor of FIG. 1A,

FIG. 1E is a cross-sectional view illustrating a structure in which a light emitter, a transparent jacket, a baffle plate, and an external heat exchanger are installed in the bubble column photobioreactor of FIG. 1A,

Figure 2a is a side view schematically showing the structure of the upper gas injection bubble column photobioreactor of the present invention,

FIG. 2B is a cross-sectional view illustrating a structure in which a light emitter, a baffle plate, a transparent jacket, and a baffle plate are installed in the bubble column photobioreactor of FIG. 2A;

FIG. 2C is a cross-sectional view illustrating a structure in which a light emitter, a baffle plate, and an internal heat exchanger are installed in the bubble column photobioreactor of FIG. 2A.

FIG. 2D is a cross-sectional view illustrating a structure in which a light emitter, a baffle plate, and an external heat exchanger are installed in the bubble column photobioreactor of FIG. 2A;

3a and 3b are a side view and a plan view schematically showing the structure of the bottom gas injection bubble column photobioreactor according to an embodiment of the present invention,

3C and 3D are graphs showing the results of culturing photosynthetic microorganisms using the bubble column photobioreactor of FIGS. 3A and 3B.

<Description of the symbols for the main parts of the drawings>

1: gas inlet 2: wire

3: single transparent jacket 4: light emitter

5: baffle plate 6: upflow culture medium

7: Downflow culture medium 8: Transparent outer column

9: bubble 10: internal heat exchanger

11: external heat exchanger 12: aeration device

In order to achieve the above object, the present invention provides a photobioreactor capable of culturing photosynthetic microorganisms in high concentration and a method of culturing photosynthetic microorganisms using the same.

Hereinafter, the present invention will be described in detail.

The present invention includes a photobioreactor capable of cultivating a high concentration of photosynthetic microorganisms. Specifically, the present invention

A transparent outer column having a vertical cylindrical shape to form a chamber capable of containing the microbial culture;

A light emitter which is installed at the center of the outer column and irradiates light energy to the front surface of the culture medium without disturbing the circulation of the culture medium;

A vertical cylindrical transparent jacket separating the light emitting body from the culture solution and allowing heat exchange;

A baffle plate having a transparent plate shape formed on an outer surface of the transparent jacket to form a circulation path by distinguishing a rising part and a lower part of the culture solution; And

It provides a bubble column photobioreactor comprising an aeration device for causing the upward flow of the culture by supplying the gas upward from the lower end of one portion divided by the baffle plate.

That is, the bubble column photobioreactor of the present invention is a light emitting material for supplying light energy to the center of the reactor for applying the conventional bubble column bioreactor to the culture of photosynthetic organisms, a baffle plate for inducing the circulation of the culture solution, for temperature control It is characterized by adding a heat exchanger function.

The light emitter of the present invention is installed at the center of the outer jacket so as to evenly irradiate the culture without disturbing the flow of the fluid, it uses a selected from straight tube fluorescent lamps, optical fibers, neon tubes, light emitting diode elements. In addition, in order to prevent direct contact between the light emitting body and the culture medium, the light emitting body is wrapped in a vertical cylindrical transparent jacket.

The operation of the luminous body is basically based on using sunlight as a light energy source, and additional light energy, which is insufficient due to seasonal (winter), time (night), meteorological (cloudy) factors, and cell growth, is added using the internal luminous body. It is preferable to supply. In addition, it is also possible to supply light energy using only internal lighting when installed in a small capacity indoors for spawn culture and research.

The present invention installs a heat exchanger to maintain the temperature of the culture in a state optimal for photosynthetic microbial growth. The heat exchanger prevents an increase in the temperature of the culture medium by converting the high temperature of the summer, the internal heat of the luminescent body, the heat of the cell metabolism and the light energy which is not absorbed by the cells into the thermal energy, and on the contrary, in the winter or at night, the incubation temperature falls below an appropriate temperature. Prevent cell growth. For example, when a large amount of heat is generated in the light emitter and the temperature change of the culture solution is large, or when micro temperature control is required for research, it is possible to manufacture a cylindrical transparent jacket containing the light emitter as a double jacket and connect it to the thermostatic circulator. In addition, when it is installed indoors and there is no big change or it is used for large-scale commercial cultivation, it is possible to spray the coolant to the outer surface of the reactor by using a sprinkler without double jacket or to control the temperature of the culture liquid by air cooling by introducing a cooling fan. Do.

Baffle plate in the form of a transparent plate installed in a cylindrical transparent jacket containing a light emitting body improves the mass transfer rate and the mixing degree of the culture medium in a general bubble column reactor, increases the flashing light effect, and also serves as a support for the internal light source. Done. At this time, the aeration device circulates the culture medium without a separate stirrer by flowing the culture medium upward from the lower part of one part divided into the baffle plate through the injection port installed at the upper or lower part of the photobioreactor and then downwardly flowing to the other part. This is possible. However, cultivation of photosynthetic microorganisms with severe cell adhesion to the inner wall of the reactor is possible without a baffle plate, in which case there is a local upward and downward flow of the culture solution.

Hereinafter, with reference to the accompanying drawings to illustrate the embodiments of the present invention in more detail, the following examples are merely to help the understanding of the present invention and the present invention is not limited thereto.

1A and 2A show side views of two types of bubble column photobioreactors according to an exemplary embodiment of the present invention. The light emitter uses a straight fluorescent lamp 4 and uses a wire 2 to stabilize and blink. The switch is connected. In addition, a baffle plate 5 for inducing the flow of the upflow culture medium 6 and the downflow culture medium 7 is installed, and the flow of the culture solution is due to the density difference due to the bubbles 8 in the upflow culture medium.

The structural difference between the two bubble column photobioreactors is that the gas supply device 1 is installed at the bottom of the reactor in the case of the reactor of Figure 1a, the reactor of Figure 2a is installed to be injected from the top of the reactor. And baffle plates of the reactor, Figure 1a is a form installed in the position of the transparent external jacket (3) wrapped in a light-emitter, the reactor of Figure 2a has a baffle-plate installed at the center of the reactor. The difference in the installation position of the baffle plate is to maximize the mixing efficiency and the flashing light effect by controlling the cross-sectional area of the upflowed medium ( A _r ) and the downflowed culture medium ( A _d ). The optimal ratio ( A _r / A _d ) varies depending on the type of.

In the lower gas injection bubble column photobioreactor of FIG. 1A , a straight tube fluorescent lamp 4 and a transparent jacket 3 are installed , and a straight tube fluorescent lamp, a transparent jacket, and a baffle plate 5 are external positions of the transparent jacket. 1c , a straight tube fluorescent lamp, a baffle plate, and a double jacket of FIG. 1c , a straight tube fluorescent lamp, a baffle plate, and an internal heat exchanger 10 of a method of connecting to a transparent double jacket and a constant temperature circulator installed in FIG. It can be modified in the form of Figure 1e consisting of an external heat exchanger 11 of the method of connecting to a constant temperature circulator.

An upper gas injection type group modified turret photobioreactor of Figure 2a are fluorescent lamps, transparent jacket, and the baffle plate (5) and Figure 2b is installed to pass through the center of the reactor, a fluorescent lamp, a baffle plate, and a heat exchanger It is possible to design and manufacture a bubble column photobioreactor in the form of FIG. 2D having a structure in which 10 is installed, FIG . 2D composed of a straight tube fluorescent lamp, a baffle plate, and an external heat exchanger 11.

<Example 1>

The bubble column photobioreactor of the type shown in the side view of FIG . 3A and the top view of FIG. 3B was manufactured to enable a culture volume of 2 L with a lower gas injection type. As a photosynthetic microorganism, a strain of chlorella ( Chlorella kessleri UTEX398), which is a kind of microalgae , was used as a nutrient medium, and N-8 was used, and a batch culture was performed by maintaining aeration at 2 L / min. In this case, a linear fluorescent lamp was used as the internal light emitting body, and the surface luminance of the transparent jacket in which the lamp was installed was 150 μmol / m 2 / s. In addition, a transparent baffle plate was installed inside to induce an improvement in mass transfer rate and an improvement in fluid flow. A constant temperature circulator was connected to the transparent double jacket of the reactor to maintain a culture temperature of 25 ° C.

Experimental Example 1 Measurement of Dry Cell Weight and Cell Concentration According to Incubation Time

The culture was carried out under the same conditions as in Example 1, and the dry cell weight and cell concentration were measured according to the incubation time (daily unit) (Lee and Palsson, 1994, Biotechnol. Bioeng. , 44 : 1161-1167; Lee and Lee, 2001, Biotechnol.Bioprocess Eng. , 6 : 194-199). The results are shown in Figures 3c and 3d . 3C shows the dry cell weight and the cell concentration according to the culturing time, and FIG . 3D shows the change in temperature and pH at this time.

As shown in FIG . 3C and FIG. 3D , the cells grew rapidly after the start of the culture, showed exponential growth until 2 days, and then linearly grew, and entered the stationary phase after 6 days of culture. At this time, the incubation temperature was kept constant, and the pH gradually increased as the cell concentration increased. The final culture resulted in a cell concentration of up to 2.5 × 10 ⁷ cell / ml and a dry cell weight of 0.54 g / l. Photobioreactors of this type can be expected to achieve better culture results by irradiation of sunlight through outdoor culture or by adding fluorescent lamps to the outside of the reactor.

The bubble column photobioreactor according to the present invention is capable of circulating a culture medium without a separate stirrer by allowing the air or other gas injected upward to one part of the transparent baffle plate by the aeration device to flow the culture medium upward and downward to the opposite side. In addition, the light transmission distance into the circulating culture medium is minimized by introducing the light emitter into the transparent baffle plate, and light energy can be transferred to the maximum surface area of the culture medium, which is suitable for high concentration mass culture of photosynthetic microorganisms.

Claims (7)

A transparent outer column having a vertical cylindrical shape to form a chamber capable of containing the microbial culture; A light emitter which is installed at the center of the outer column and irradiates light energy to the front surface of the culture medium without disturbing the circulation of the culture medium; A vertical cylindrical transparent jacket separating the light emitting body from the culture solution and allowing heat exchange; A baffle plate having a transparent plate shape formed on an outer surface of the transparent jacket to form a circulation path by distinguishing a rising part and a lower part of the culture solution; And Bubble column optical bioreactor characterized in that it comprises an aeration device for causing the upward flow of the culture by supplying the gas upward from the lower end of one portion divided by the baffle plate. The bubble column photobioreactor of claim 1, wherein the light emitter is selected from a straight tube fluorescent lamp, an optical fiber bundle, a neon tube, and a light emitting diode device. The bubble column optical organism according to claim 1, wherein when the light emitter is a straight fluorescent lamp or a light emitting diode device, arranging one or more fluorescent lamps or light emitting diode devices at a center position of the outer column by stacking them upwards. Reactor. The bubble column photobioreactor of claim 1, wherein the transparent jacket is formed of a double jacket to receive constant temperature cooling water or hot water from a constant temperature circulator. The bubble column photobioreactor of claim 1, wherein the transparent outer column is made of a double jacket to receive constant temperature cooling water or hot water from a constant temperature circulator. The method of claim 1, wherein when the supply of light energy to the bubble column photobioreactor is sufficient, only sunlight is used, and when insufficient, additional light emitters are provided outside the reactor to supply additional light energy. Bubble column photobioreactor. The method of claim 1, further comprising an internal heat exchanger and / or an external heat exchanger for maintaining the optimum temperature change of the culture medium according to the change of season and day and night, the metabolic heat of the cells, the degree of consumption of light energy. Bubble column photobioreactor.