JPS6075288A - Production of hydrogen by microorganism - Google Patents

Abstract

PURPOSE:To produce hydrogen, by the mixed culture of a photosynthetic bacterial strain belonging to Rhodopseudomonas genus and a bacterial strain belonging to Clostridium genus in a medium containing glucose. CONSTITUTION:A novel photosynthetic bacterial strain, Rhodopseudomonas SP. RV (FERM-P No.7254) has been separated from a natural source. The strain is cultured in combination with a strain belonging to Clostridium genus, e.g. Clostridium bacillicum (IFO13949) in a conventional medium containing <=1g/ml of glucose at 25-35 deg.C in the presence of light. Butyric acid and acetic acid, etc. are produced from glucose in the first stage by the action of the bacteria belonging to clostridium genus, and hydrogen is produced in the second stage by Rhodopseudomonas SP.RV from the produced organic acids.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention produces hydrogen from glucose by a microbial method.

The organic resources that exist on earth are substances such as cellulose that have glucose as the basic unit.Therefore, efficient methods of using glucose have been studied in recent years. Methods of efficiently decomposing hydrogen and converting it into hydrogen are being studied.

Conventionally, photosynthetic bacteria have been known to efficiently convert organic acids such as malic acid and lactic acid into hydrogen, but their efficiency in converting sugars such as 7-cose into hydrogen is generally low.

Bacteria belonging to the genus Clostridium are also known to have the ability to convert sugars and other substances into hydrogen, and there is an upper limit when converting sugars such as glucose into hydrogen, and only a certain amount of hydrogen can be used. I can't get it.

The reason for this is that bacteria of the genus Clostrium cannot completely decompose glucose into carbon dioxide and hydrogen, but instead decompose it into carbon dioxide, organic acids, and hydrogen.

On the other hand, recent examples of hydrogen production from glucose through mixed culture of photosynthetic bacteria and other bacteria include Rhodospirillum rubrum and Klebsiella e = mnemonia (Biotechnol, &Bioengineering).
ring 198LVoI23), and Rhodospirillum rubrum and Clostridium butyricum (Japanese Science and Technology 1983).

Therefore, the present inventors have conducted intensive research on hydrogen production from photosynthetic bacteria, mainly Rhodopseudomonas cavusulata-like bacteria newly isolated from the natural world, and commercially available cloth. This led to the completion of the invention.

That is, the present invention relates to a hydrogen production method using a microorganism, which is characterized in that a photosynthetic bacterium belonging to the genus Rhodomonas and a bacterium belonging to the genus Clostridium are mixedly cultured in producing hydrogen from glucose by a microbial method. .

The mycological properties of this strain are as shown below.

1″A logical property Shape: Oval, not twisted.

Bacteriochlorophyll and mosquitoes It has rotinoid and has a reddish brown color. do.

′Growth conditions: Ability to grow and assimilate organic acids such as acetic acid, lactic acid, butyric acid, and malic acid as carbon sources under anaerobic conditions and light irradiation (anaerobic and under light irradiation) Thiosulfuric acid − Propionic acid Decamannitol + Sorbitol + Vitamin requirement Biotin - Based on the above mycology and milk quality, a search using the Virgier Manual 7th edition revealed that it is a non-sulfur photosynthetic bacterium because it has photosynthetic pigments, grows under light irradiation, and does not have sulfur grains in its body. It was recognized that

Among non-sulfur photosynthetic bacteria, the genus Rhodosium
eudomonas).

In addition, Rhodos pseudomonas capsulata (Rh) does not grow in thiosulfate but grows in propionic acid.
odopseudomonas capsulata)
It was recognized that However, since Rhodoshutomonas capsulata is said to not grow in mannitol or sorbitol, this bacterium is Rhodoshutomonas capsulata.
Although it is similar to Kabusulata, it is also thought to be a new box belonging to Rhodopseudomonas. This strain was tentatively named Rhodopseudomonas X5P-RV.
FERM P-,,,7,? It has been deposited as number r+.

As the photosynthetic bacterium used in the present invention, any bacterium of the genus Rhodomonas may be used, and the above-mentioned Rhodopseudomonas RV-1 can be exemplified as a suitable bacterium.

The bacteria of the genus Clostridium may be any bacteria of the genus, and commercially available Clostridium vaticum (IFO13949) is a representative example.

Production of hydrogen from glucose by mixed culture of these bacteria is usually carried out in the coexistence of glucose and light of less than l'l/- to the medium, but other culture sources include, for example,
Cultured using the following nutrient medium:

In addition, the culture temperature is 25 to 35°C, preferably 30°C.
di'j, < 4 The pH is also preferably 7 to 9, preferably around 8.

Medium composition (Table 1) Sodium phosphate 0.1 M Glucose 5QmM Glutamic acid 13mM Peptone 0.1% Yeast extract 0.1'.% Meat extract 0.05% FeSO40,001% MgF304 0.02% EDTA O,002 “7% Vitamins Biotin, B2, Paba, Trace N
1 cotinate pH Trace amounts of other metal compounds It is also possible to use a mixture of these bacteria encased in a conventional immobilization carrier such as agar, carrageenan, or polyacrylamide. In immobilization, immobilization of a mixture of bacteria by gel entrapment is more effective for stabilization due to the coexistence of bacteria and shows better results than immobilization of bacteria alone.

Next, in the first stage of hydrogen production, Clostridium bacteria produce hydrogen such as butyric acid and acetic acid from glucose.

Next, photosynthetic bacteria utilize the organic acids produced to produce hydrogen.

In this way, coexisting bacteria interact with each other. For this reason, when Clostridium bacteria are used alone, the pH of the medium tends to decrease due to organic acids, but in a mixed system, GM-containing bacteria produced
Immediately utilized by the coexisting photosynthetic bacteria, the pHg of the medium
) The decline will no longer occur and it will become stable. On the other hand, compared to the case where only photosynthetic bacteria are used, in a mixed system, each of the coexisting bacteria produces hydrogen, resulting in a faster hydrogen production rate.

Next, the irradiation of light to photosynthetic bacteria is usually 1 kl u
x to 100 klux, and the light source is appropriately selected from sunlight, artificial light, etc.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 0 Dosyudomonas SI)-RV (FERMP-7”
(25'r) 100■ (wet) and Clostridium batylicum (IFO13949) 40111g (W
40-2% agar mixed with O2 and dissolved using medium D from Table 2 in a 200 rnl flat glass culture bottle.
immobilized inside. (Gel dimensions: 120 x 55 x 6) Next, add medium A160. from Table 2 to a culture bottle. Enter z,
After culturing anaerobically under light irradiation (lklux) for 2 days, the medium was replaced with B medium in Table 2, and 10klu was grown anaerobically.
x light irradiation was performed. The culture bottle was kept in a 30°C constant temperature bath.

As shown in the figure, stable hydrogen generation continued for 200 hours. As a result, approximately 9 m from 1 mol of glucose
It was observed that ol hydrogen was generated.

Furthermore, as shown in the figure, the pHtD fluctuation of the medium was also relatively small.

Medium composition (Table 2) A medium B medium C medium Na2HPO4 100mM 100mM 100mM
100mM glucose 501TIM32.5mM 0
50mM butyric acid 0 0 50mM Q glutamic acid IQmM 1.25mM 10mM O
Yeast Extract X O.02% OO0.4% Peptone 0.
02% o o o, t,;s meat extract o, oi %
o o o, z, *2HP0. 4.2mM Same as left
Same as left Same as left K) I2PO45,4mM tt 〃〃Mg
SO4,' 17mM // tt ttFeSO478
μlvi tt tt ttCaC12680ILM
tt 〃ttEDTA 50μM // // ttH
3B03 45μM // JF ttNa2Mo04
・2H208, 8μM /I /F //ZrbSO4
・7H200, 8μl VI tt // // MII
SO4" 4H209,4PM tt tt 〃Biotin Trace amount 〃〃〃 Vitamin B, same as above 〃〃〃 p-aminobenzoic acid Same as above 〃〃〃 Nicotinic acid Same as above 〃〃〃 Nicotinic acid amide Same as above 〃〃〃 pH8888 Example 2 0 Dosyudomonas 5P- RV (FERMP-N
(L q2F4) 100 ma (wet) to 20
0. J'+7) 40% 2% agar dissolved using medium D from Table 2 in a flat glass culture bottle. After immobilization in nl, the cells were cultured for 2 days in C medium shown in Table 3. Similarly, after immobilizing Clostridium vaticum (IFO13949) 40- in 2% agar 10- by the same method as above, the third
The cells were cultured in medium D shown in the table for 2 days.

Next, replace the medium with B medium in Table 2 and anaerobically add 10 klu.
As a result of the x light irradiation, about 3.8 mol of hydrogen was obtained from 1 mol of glucose.

From this experimental result, it is better to immobilize a mixture of bacteria as shown in Example 1 than to immobilize each bacteria individually.
It was recognized that the hydrogen production capacity was higher.

[Brief explanation of drawings]

The figure shows hydrogen production from glucose by mixed immobilization culture of Rhodopseudomonas 5P-RV and Clostridium vaticilium, and the vertical axis shows hydrogen production 0 100 200

Claims (1)

[Claims] A microbial hydrogen production method characterized by culturing a mixture of photosynthetic bacteria belonging to the genus Rhodopseudomonas and bacteria belonging to the genus Clostridium in producing hydrogen from glucose by a microbial method.