JP3540540B2

JP3540540B2 - Photosynthetic microorganism culture equipment

Info

Publication number: JP3540540B2
Application number: JP651897A
Authority: JP
Inventors: 広明須藤; 和典松本
Original assignee: Mitsubishi Heavy Industries Ltd; Research Institute of Innovative Technology for the Earth RITE
Current assignee: Mitsubishi Heavy Industries Ltd; Research Institute of Innovative Technology for the Earth RITE
Priority date: 1997-01-17
Filing date: 1997-01-17
Publication date: 2004-07-07
Anticipated expiration: 2017-01-17
Also published as: JPH10191957A

Description

【０００１】
【発明の属する技術分野】
本発明は光合成微生物を包括固定化した状態で培養する光合成微生物培養装置及び培養方法に関する。
【０００２】
【従来の技術】
従来、大気中あるいは各種排ガス中のＣＯ₂の固定化などを目的としてクロレラ、スピルリナなどの光合成微生物の培養が試みられている。これらの光合成微生物を培養する方法として、寒天、カラギーナン、ゲランガムなどの微生物包括固定化用担体を用いて包括固定化し、培養する方法がある。この包括固定化法を利用した光合成微生物培養装置の１例を図４に示す。図４の装置においては光合成微生物を包括固定化しビーズ状に成形した固定化微生物１５を培地１４に懸濁させて培養槽７に入れ、該培養槽７を温度制御が可能な水槽６中に設置し、ガス混合装置３でＣＯ₂ボンベ５からのＣＯ₂とエアポンプ１０から送られる空気を混合したガスをガス流入ライン１６から通気するとともに、光供給装置１から光を供給して培養を行う。図４中の２は水槽６の温度を制御する温度コントローラー、１７はガス排出ラインである。
【０００３】
【発明が解決しようとする課題】
前記のような従来法では包括固定化光合成微生物に十分均一な光が供給できず、固定化担体の中心部にある微生物ほど光が遮蔽され、増殖できない。さらに固定化ゲルが培地中に分散した状態であることから入射強度が一定とならない。
本発明はこのような従来技術の実状に鑑み、光の利用効率の高い光合成微生物の培養装置及び培養方法を提供することを目的とする。
【０００４】
【課題を解決するための手段】
本発明は平板状の発光面に該発光面を底面とする凹部を設けるか、あるいは該発光面の周囲に枠を設けて前記凹部あるいは枠内の前記平板状の発光面に光合成微生物を微生物包括固定化用担体と混合した光合成微生物の包括固定化ゲルの薄板を貼着可能に形成された発光板と、該発光板を装着して光合成微生物の培養を行う培養槽と、該発光板に光を供給する光供給手段と、培養槽内に炭酸ガスを供給する炭酸ガス供給手段とを備えてなることを特徴とする光合成微生物培養装置及び発光板における平板状の発光面に該発光面を底面とする凹部を設けるか、あるいは該発光面の周囲に枠を設けて前記凹部あるいは枠内の前記平板状の発光面に光合成微生物を微生物包括固定化用担体と混合した光合成微生物の包括固定化ゲルの薄板を貼着し、該包括固定化ゲルの薄板を貼着した発光板を培地を入れた培養槽内に装着し、炭酸ガスを供給するとともに薄板状の光合成微生物の包括固定化ゲルに均一に光を照射しながら培養することを特徴とする光合成微生物の培養方法である。
【０００５】
本発明の培養装置又は培養方法により培養する光合成微生物の具体例としては大気中あるいは各種排ガス中のＣＯ₂を固定するためのクロレラ、スピルリナ、ポルフィリジウム、クロロコッカムなどの微細藻類などが挙げられる。
【０００６】
これらの光合成微生物を寒天、カラギーナン、ゲランガムなどの微生物包括固定化用担体と混合してゲル状とし、発光板の発光面に薄板状に貼着した形で培養を行う。光合成微生物の包括固定化ゲル薄板の厚みは、光が内部まで十分到達できる範囲とすればよく、通常は３ｍｍ前後が好ましい。
【０００７】
本発明の培養装置では培養のための光源として発光面が平板状（発光面全体から均一な光が供給される）の発光板を使用する。この発光板は、例えば表面に発光面を底面とする凹部を設けるかあるいは発光面の周囲に所定の高さの枠を設けるなどの方法により、その発光面に前記の薄板状の光合成微生物の包括固定化ゲルを貼着できる形状に構成されている。
【０００８】
発光板の発光面に薄板状の光合成微生物の包括固定化ゲルを貼着する方法としては、予め光合成微生物の包括固定化ゲルを薄板状に成形したものを貼着する方法、ゲルを発光面に塗布して薄板を形成させる方法、ゲルを形成する懸濁液を供給して発光面上でゲル化させる方法などを採ることができる。ゲルの貼着に際し、予め発光面にステンレス鋼やアルミニウムなどの金属、合成樹脂などの網目状や多孔状の薄板に加工でき、光合成微生物に対する毒性が少ない材質からなる網目状や多孔状の薄板などの固定器具を貼り付けておくことによりゲルの発光面への接着性を向上させることができる。
【０００９】
発光面に薄板状の光合成微生物の包括固定化ゲルを貼着した発光板を培養槽に入れ、培地（培養液）、ＣＯ₂ガス及び光を供給し、恒温槽中で所定の温度に保持しながら培養する。
光合成微生物を包括固定化したゲルは内部に光が十分到達できる程度に薄いため、ゲルのどの位置に細胞が存在していても均一な光が安定して供給可能になる。
【００１０】
本発明の光合成微生物培養装置の１例についてその基本構成を図１に示す。この装置において、平面型の発光板８には微生物包括固定化ゲル１２（図２参照）が薄く接着されている。これを培地が入った培養槽７に入れ、水槽６中に設置して温度コントローラ２で温度コントロールする。これらの培養槽７にＣＯ₂ボンベ５からガス混合装置３を経てＣＯ₂混合ガスを供給する。ＣＯ₂濃度はガス混合装置３でエアコンプレッサ４からの空気との混合により調整する。光は光供給装置１から光ファイバ９により供給する。図２に本発明に係る発光面に薄板状の光合成微生物の包括固定化ゲル１２を貼着した発光板８の模式図を示す。図２（ａ）は正面から見た一部切欠き断面図、図２（ｂ）は側面から見た断面図である。発光板８の片面は凹状で、微生物（例：藻類）包括固定化ゲル１２がゲル固定器具１３を介して接着されている。固定器具１３は網目状の薄い板を発光板８に貼り付けたもので、ゲルの発光板８への接着力を高めている。
【００１１】
なお、図２（ｃ）に示すように発光板の裏表に凹状部を設けて微生物包括固定化ゲル１２を貼着したり、多面体状の発光体を使用し、複数の発光面に微生物包括固定化ゲル１２を貼着するようにしてもよい。
【００１２】
【実施例】
以下実施例により本発明をさらに具体的に説明する。本発明の効果を実証するため、図１に示す構成の装置を使用して光合成微生物の培養試験を行った。
（１）培養装置
図１に示す構成の培養装置（培養槽７の設置数は４基）を使用した。光源にはメタルハライドランプを使用し、光ファイバ９で発光板８（発光面の面積約６００ｃｍ²）まで光を伝達するようにした。光合成微生物である藻体の包括固定化ゲル１２を接着させた発光板８を、１リットルの培地１４を注入した培養槽７に入れ、これを水槽６に設置し温度コントローラ２で培養温度をコントロールするようにした。
【００１３】
（２）培養方法及び培養条件
本試験に使用した光合成微生物である藻体（ Porphyridium cruentum R-1）は次のような手順で包括固定化した。まず、３重量％食塩水に寒天６ｇを加え１００ミリリットルとし、オートクレーブ中で１２１℃で１５分間加熱し溶解後、５０℃まで冷却した。これに前記藻体の懸濁液を５×１０⁵ｃｅｌｌｓ／ミリリットルになるよう混合し、表面に硬質塩化ビニル樹脂製の網目状の薄板をゲル固定器具として貼り付けた発光板の凹形の枠内に注入して２４時間放置して固化させ、藻体包括固定化ゲル接着発光板とした（図２（ａ）及び（ｂ）の形状、ゲルの厚み３ｍｍ）。これを上記の培養装置７に入れ、ＣＯ₂濃度を調整した空気を通気して培養し、藻体数から、別途藻体数と藻体乾燥重量を別々に測定して作成した藻体数と藻体乾燥重量との関係を表す換算式を用いて藻体乾燥重量を算出した。培養条件は表１に示すとおりである。
【００１４】
【表１】

【００１５】
（３）測定分析方法
所定時間培養後の藻体包括固定化ゲルを採取し、オートクレーブ中で１２１℃で１分間加熱溶解後、藻体数を顕微鏡観察下、ヘマサイトメーターを用いて測定した。菌体数は別途作成した換算式で乾燥重量値に変換した。
【００１６】
（４）試験結果
試験結果を図３に示す。培養開始時点での藻体の乾燥重量が約５０ｍｇ／リットルであったものが、光強度５１．８μＥｉｎｓｔｅｉｎ／ｍ²／ｓの場合には２５０時間で約１８１０ｍｇ／リットルまで増殖していた。これは従来の培養法で得られていた値と同レベルであることから、本発明の培養装置及び培養方法の適用性が確認され、従来法での必要光強度１３０μＥｉｎｓｔｅｉｎ／ｍ²／ｓ（２５０時間で約１８００ｍｇ／リットルまで増殖させるのに必要な光強度）に比較して低い光強度でよいことが判明した。光強度が強いほど増殖は早いが、３８．５μＥｉｎｓｔｅｉｎ／ｍ²／ｓの場合でも２５０時間で約１５００ｍｇ／リットルまで増殖している。なお、増殖した藻体は一部培地中にも分散するが、藻体は主としてゲル中で増殖していた。
【００１７】
【発明の効果】
包括固定化ゲルのどの位置に細胞が存在していても均一な光が供給されるため低光強度でも従来法に比較して増殖機能が向上する。
【図面の簡単な説明】
【図１】本発明に係る光合成微生物培養装置の１例を示す基本構成図。
【図２】本発明の実施例に係る微生物固定化発光板の模式図。
【図３】本発明の実施例に係る固定化光合成微生物の増殖曲線。
【図４】従来の光合成微生物培養装置の１例を示す構成図。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a photosynthetic microorganism culturing apparatus and a culturing method for culturing photosynthetic microorganisms in a state of being immobilized in a comprehensive manner.
[0002]
[Prior art]
BACKGROUND ART Conventionally, culture of photosynthetic microorganisms such as chlorella and spirulina has been attempted for the purpose of immobilizing CO _{2 in} the atmosphere or various exhaust gases. As a method of culturing these photosynthetic microorganisms, there is a method of entrapping and immobilizing them using a carrier for entrapping and immobilizing microorganisms such as agar, carrageenan, and gellan gum. FIG. 4 shows an example of a photosynthetic microorganism culturing apparatus using this entrapping immobilization method. In the apparatus shown in FIG. 4, immobilized microorganisms 15 formed into beads by encapsulating and immobilizing photosynthetic microorganisms are suspended in a medium 14 and placed in a culture tank 7, and the culture tank 7 is set in a water tank 6 capable of controlling temperature. and, while venting the gas mixed with air delivered from the CO ₂ and the air pump 10 from CO ₂ cylinder 5 in a gas mixing device 3 from a gas inlet line 16, the culture is performed by supplying the light from the light supply device 1. 4 is a temperature controller for controlling the temperature of the water tank 6, and 17 is a gas discharge line.
[0003]
[Problems to be solved by the invention]
In the conventional method as described above, sufficiently uniform light cannot be supplied to the entrapping immobilized photosynthetic microorganisms, and the microorganisms at the center of the immobilized carrier are blocked from light and cannot grow. Further, since the immobilized gel is dispersed in the medium, the incident intensity is not constant.
An object of the present invention is to provide a culturing apparatus and a culturing method for photosynthetic microorganisms having high light use efficiency in view of the state of the prior art.
[0004]
[Means for Solving the Problems]
The present invention provides a plate-shaped light- emitting surface with a recess having the light-emitting surface as a bottom surface, or a frame provided around the light-emitting surface, and covers the concave or the plate-shaped light-emitting surface in the frame with microbes containing photosynthetic microorganisms. A light-emitting plate formed so that a thin plate of an entrapping immobilization gel of photosynthetic microorganisms mixed with a carrier for immobilization can be attached thereto, a culture tank for mounting the light-emitting plate and culturing the photosynthetic microorganisms, and A light supply means for supplying a gas, and a carbon dioxide gas supply means for supplying a carbon dioxide gas into the culture tank, wherein the photosynthetic microorganism culturing apparatus and the light-emitting plate have a flat light-emitting surface on the bottom surface. Or a frame around the light emitting surface, and a photosynthetic microorganism entrapping immobilization gel obtained by mixing a photosynthetic microorganism with a microorganism entrapping and immobilizing carrier on the flat light emitting surface in the recess or the frame. and wearing pasting a thin plate, The light-emitting plate with the thin plate of the entrapping immobilized gel attached is mounted in the culture tank containing the culture medium, and the culture is performed while supplying carbon dioxide gas and irradiating light uniformly to the entrapping immobilized gel of the photosynthetic microorganisms in the form of a thin plate. A method for culturing photosynthetic microorganisms, characterized in that:
[0005]
Specific examples of photosynthetic microorganisms cultured by the culture apparatus or the culture method of the present invention include microalgae such as chlorella, spirulina, porphyridium, and chlorocockum for fixing CO ₂ in the air or various exhaust gases.
[0006]
These photosynthetic microorganisms are mixed with a carrier for entrapping and immobilizing microorganisms such as agar, carrageenan and gellan gum to form a gel, which is then cultured in the form of a thin plate adhered to the light emitting surface of a light emitting plate. The thickness of the entrapping immobilized gel thin plate for photosynthetic microorganisms may be in a range where light can sufficiently reach the inside, and is usually preferably about 3 mm.
[0007]
In the culture apparatus of the present invention, a light emitting plate having a flat light emitting surface (a uniform light is supplied from the entire light emitting surface) is used as a light source for culture. The light-emitting plate is provided with the thin plate-like photosynthetic microorganisms on its light-emitting surface by, for example, providing a concave portion having a light-emitting surface as a bottom surface or providing a frame of a predetermined height around the light-emitting surface. It is configured in a shape to which the immobilized gel can be attached.
[0008]
As a method of attaching a thin immobilized gel of photosynthetic microorganisms to the light-emitting surface of the light-emitting plate, a method of attaching a preformed immobilized gel of photosynthetic microorganisms to a thin plate in advance, and attaching the gel to the light-emitting surface A method of forming a thin plate by coating, a method of supplying a suspension for forming a gel and gelling on a light emitting surface, and the like can be adopted. When applying the gel, the light-emitting surface can be processed in advance into a mesh or porous thin plate of metal such as stainless steel or aluminum, synthetic resin, etc., and a mesh or porous thin plate made of a material with low toxicity to photosynthetic microorganisms, etc. By pasting the fixing device, the adhesiveness of the gel to the light emitting surface can be improved.
[0009]
The light-emitting plate, on which a thin immobilized immobilized gel of photosynthetic microorganisms is stuck on the light-emitting surface, is placed in a culture tank, a medium (culture solution), CO ₂ gas and light are supplied, and the temperature is maintained at a predetermined temperature in a thermostat. While culturing.
The gel in which the photosynthetic microorganisms are entrapped and immobilized is thin enough to allow sufficient light to reach the inside, so that uniform light can be stably supplied no matter where the cells are located in the gel.
[0010]
FIG. 1 shows the basic configuration of one example of the photosynthetic microorganism culturing apparatus of the present invention. In this device, a microbe-encapsulated and immobilized gel 12 (see FIG. 2) is thinly adhered to a flat light emitting plate 8. This is put in a culture tank 7 containing a medium, placed in a water tank 6, and temperature-controlled by a temperature controller 2. A CO ₂ mixed gas is supplied to these culture tanks 7 from a CO ₂ cylinder 5 via a gas mixing device 3. The CO ₂ concentration is adjusted by mixing with the air from the air compressor 4 in the gas mixing device 3. Light is supplied from the light supply device 1 by an optical fiber 9. FIG. 2 is a schematic view of a light emitting plate 8 according to the present invention, in which a thin plate-like entrapping immobilization gel 12 of photosynthetic microorganisms is adhered to a light emitting surface. 2A is a partially cutaway cross-sectional view as viewed from the front, and FIG. 2B is a cross-sectional view as viewed from the side. One surface of the light-emitting plate 8 is concave, and a microorganism (eg, algae) entrapping immobilization gel 12 is adhered thereto via a gel fixing device 13. The fixing device 13 is formed by attaching a thin net-like plate to the light-emitting plate 8 to increase the adhesive force of the gel to the light-emitting plate 8.
[0011]
In addition, as shown in FIG. 2 (c), a concave portion is provided on the front and back of the light emitting plate, and the microorganism entrapping immobilization gel 12 is adhered. Alternatively, the gel 12 may be adhered.
[0012]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. In order to demonstrate the effects of the present invention, a culture test of photosynthetic microorganisms was performed using the apparatus having the configuration shown in FIG.
(1) Culture device A culture device having the configuration shown in FIG. A metal halide lamp was used as a light source, and light was transmitted to the light emitting plate 8 (area of the light emitting surface: about 600 cm ² ) by the optical fiber 9. The luminescent plate 8 to which the immobilized immobilized gel 12 of algae, which is a photosynthetic microorganism, is adhered is placed in the culture tank 7 into which 1 liter of the medium 14 has been injected, and this is placed in the water tank 6 and the culture temperature is controlled by the temperature controller 2. I did it.
[0013]
(2) Culture method and culture conditions Algae (Porphyridium cruentum R-1), which is a photosynthetic microorganism used in this test, were comprehensively immobilized by the following procedure. First, 6 g of agar was added to a 3% by weight saline solution to make 100 ml, heated and dissolved in an autoclave at 121 ° C. for 15 minutes, and then cooled to 50 ° C. The suspension of the algal cells was mixed with the suspension at a concentration of 5 × 10 ⁵ cells / ml, and a mesh-like thin plate made of hard vinyl chloride resin was adhered to the surface as a gel fixing device to form a concave frame of a light emitting plate. The mixture was allowed to stand for 24 hours to be solidified, thereby obtaining a gel-adhered luminescent plate immobilized on algae bodies (shapes shown in FIGS. 2A and 2B and a gel thickness of 3 mm). This was put into the above-mentioned culturing apparatus 7, and cultured with ventilation of air adjusted to CO ₂ concentration. From the number of algal bodies, the number of algal bodies and the algal body dry weight separately measured were separately measured. The algal dry weight was calculated using a conversion formula representing the relationship with the algal dry weight. The culture conditions are as shown in Table 1.
[0014]
[Table 1]

[0015]
(3) Measurement / analysis method The algal cell entrapping immobilized gel after culturing for a predetermined time was collected, dissolved by heating at 121 ° C. for 1 minute in an autoclave, and the number of algal cells was measured using a hemacytometer under microscopic observation. The number of cells was converted to a dry weight value by a conversion formula prepared separately.
[0016]
(4) Test Results The test results are shown in FIG. The algal cells had a dry weight of about 50 mg / l at the start of the culture, but had grown to about 1810 mg / l in 250 hours when the light intensity was 51.8 μEinstein / m ² / s. Since this is the same level as the value obtained by the conventional culture method, the applicability of the culture apparatus and the culture method of the present invention has been confirmed, and the required light intensity of 130 μEinstein / m ² / s (250) in the conventional method has been confirmed. Light intensity required to grow to about 1800 mg / l per hour). The higher the light intensity, the faster the growth. However, even at 38.5 μEinstein / m ² / s, it grows to about 1500 mg / liter in 250 hours. Although the grown alga bodies were partially dispersed in the medium, the alga bodies grew mainly in the gel.
[0017]
【The invention's effect】
Irrespective of where the cells are located on the entrapping immobilized gel, uniform light is supplied, so that the proliferation function is improved as compared with the conventional method even at low light intensity.
[Brief description of the drawings]
FIG. 1 is a basic configuration diagram showing an example of a photosynthetic microorganism culturing apparatus according to the present invention.
FIG. 2 is a schematic view of a luminescent plate immobilized with microorganisms according to an example of the present invention.
FIG. 3 is a growth curve of an immobilized photosynthetic microorganism according to an example of the present invention.
FIG. 4 is a configuration diagram showing an example of a conventional photosynthetic microorganism culturing apparatus.

Claims

For providing a concave portion having the light-emitting surface as a bottom surface in the flat light-emitting surface , or providing a frame around the light-emitting surface, for immobilizing the photosynthetic microorganisms on the flat light-emitting surface in the concave portion or the frame . A light-emitting plate formed so that a thin plate of an entrapping immobilized gel of photosynthetic microorganisms mixed with a carrier can be attached, a culture tank to which the light-emitting plate is attached to culture the photosynthetic microorganisms, and that light is supplied to the light-emitting plate. An apparatus for culturing a photosynthetic microorganism, comprising: a light supply unit; and a carbon dioxide gas supply unit that supplies carbon dioxide gas into a culture tank.

A concave portion having the light-emitting surface as a bottom surface is provided on the flat light-emitting surface of the light-emitting plate, or a frame is provided around the light-emitting surface, and the concave or the flat light-emitting surface in the frame contains microbes containing photosynthetic microorganisms. sheet was bonded wearing entrapping immobilization gel photosynthetic microorganisms mixed with carrier for immobilizing, attached to the culture vessel containing the medium emission plate was stuck to the thin plate of the entrapping immobilization gel, supplying carbon dioxide A method for culturing photosynthetic microorganisms, which comprises irradiating light uniformly onto a plate-like immobilized immobilized gel of photosynthetic microorganisms.