JPS6349997B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention produces hydrogen from glucose using a microbial method. Organic material sources existing on the earth exist as substances such as cellulose that have glucose as the basic unit. Therefore, efficient methods of utilizing this glucose have been studied in recent years, and as one of the means of utilization, a method of efficiently decomposing glucose and converting it into hydrogen has been investigated. 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 glucose into hydrogen is generally low. Bacteria belonging to the genus Clostridium are also known to have the ability to convert sugars and organic matter into hydrogen, and there is an upper limit to the conversion of sugars such as glucose into hydrogen, and only a certain amount of hydrogen can be obtained. do not have. The reason for this is that bacteria of the genus Clostodium 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 Klebscilla pneumonia (Biotechnol &
Bioengineering 1981, VoI 23), and Rhodospirillum rubrum and Clostridium butyricum (Japanese Science and Technology 1983). Therefore, the present inventors have been conducting intensive research on hydrogen production from glucose through a mixed culture of photosynthetic bacteria, mainly Rhodosyudomonas capsulata-like bacteria recently isolated from nature, and commercially available Clostridium bacteria. As a result of these efforts, we have completed the present invention. That is, the present invention relates to a hydrogen production method using microorganisms, which is characterized in that a photosynthetic bacterium belonging to the genus Rhodosium 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. Mycological properties: Shape: oval, no twist. It contains bacteriochlorophyll and carotenoids and has a reddish-brown color. Growth conditions: Growth and assimilation ability using organic acids such as acetic acid, lactic acid, butyric acid, and malic acid as carbon sources under anaerobic and light irradiation (anaerobic and under light irradiation) Thiosulfate - Propionic acid + Mannitol + Sorbitol + Vitamin requirement niasin B ₁ Required biotin It was recognized that
Furthermore, among non-sulfur photosynthetic bacteria, it was recognized that it belongs to the genus Rhodopseudomonas due to its untwisted, oval shape. In addition, Rhodopseudomonas capsulata (Rhodopseudomonas capsulata) does not grow in thiosulfate but grows in propionic acid.
It was recognized that However, since it is said that Rhodosyutomonas capsulata does not grow in mannitol or sorbitol, this bacterium is similar to Rhodosyutomonas capsulata, or it may be a new fungus belonging to Rhodosyudomonas. This strain was tentatively named Rhodosyudomonas SP/RV, and FERMP-
It has been deposited as No. 7254. As the photosynthetic bacteria used in the present invention, any bacteria of the genus Rhodosyudomonas may be used, but suitable bacteria include the aforementioned Rhodosyudomonas RV.
-1 can be exemplified. 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 presence of glucose and light at a concentration of 1 g/ml or less per culture medium, but other culture sources may be used, such as the following nutrient medium. Further, the culture temperature is preferably 25 to 35°C, preferably around 30°C, and the pH is preferably 7 to 9, preferably around 8. Medium composition (Table 1) Sodium phosphate 0.1M Glucose 50mM Glutamic acid 10mM Peptone 0.1% Yeast extract 0.1% Meat extract 0.05% FeSO ₄ 0.001% MgSO ₄ 0.02% EDTA 0.002% Vitamins Biotin, B ₂ , Paba, Nicotinate
Trace amounts of PH Trace amounts of other metal compounds In addition, these mixed bacteria can be mixed with agar, carrageenan,
It is also possible to use it encased in a common immobilization carrier such as polyacrylamide. In immobilization, immobilization of a mixture of bacteria by gel entrapment is more effective in stabilizing bacteria due to their coexistence than immobilization of bacteria alone, and shows better results. 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 act alone, the PH of the medium tends to drop due to the organic acid, but in a mixed system, the generated organic acid is immediately utilized by the coexisting photosynthetic bacteria, and the PH of the medium does not drop, resulting in stabilization. do. 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, irradiation of light to photosynthetic bacteria usually
It is performed at 1 klux to 100 klux, and the light source is appropriately selected such as sunlight or artificial light. Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1 Rhodosyudomonas SP RV (FERMP-
7254) 100 mg (wet) and Clostridium batylicum (IFO 13949) 40 mg (wet),
The cells were immobilized in 40 ml of 2% agar dissolved using medium D in Table 2 in a 200 ml flat glass culture bottle. (Dimensions of gel: 120 x 55 x 6 mm) Next, put 160 ml of medium A in Table 2 into a culture bottle, culture under anaerobic light irradiation (1 klux) for 2 days, and then replace the medium with medium B in Table 2. Then, 10klux of light was irradiated anaerobically. 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, it was confirmed that approximately 9 mol of hydrogen was generated from 1 mol of glucose.
Furthermore, as shown in the figure, there was relatively little variation in the pH of the culture medium.

[Table] Example 2 Rhodosyudomonas SP/RV (FERMP-No.
7254) 100 mg (wet) was dissolved in a 200 ml flat glass culture bottle using D medium in Table 2.
After immobilization in 40 ml of % agar, the cells were cultured for 2 days in C medium shown in Table 3. Similarly, 40 ml of Clostridium batylicum (IFO 13949) was added in the same manner as above.
After immobilization in 10 ml of % agar, the cells were cultured for 2 days in medium D shown in Table 3. Next, replace with B medium in Table 2 and anaerobically
As a result of 10 klux light irradiation, 1 mol of glucose
Approximately 3.8 mol of hydrogen was obtained. From the results of this experiment, it was found that the hydrogen production ability was higher when a mixture of bacteria was immobilized as shown in Example 1 than when each bacteria was immobilized individually.

[Brief explanation of the drawing]

The figure shows hydrogen generation from glucose by a mixed immobilized culture of Rhodosyudomonas SP/RV and Clostridium vaticilium. The vertical axis shows the hydrogen generation amount (ml) and glucose concentration (mM), and the pH of the culture medium.
and the elapsed period is shown on the horizontal axis. Note that ●−● indicates the hydrogen generation amount, △...△ indicates the glucose concentration, and □...□ indicates the pH of the culture solution.

Claims (1)

[Claims] 1. A method for producing hydrogen from glucose using a microorganism, which is characterized by culturing a mixture of photosynthetic bacteria belonging to the genus Rhodosyudomonas and bacteria belonging to the genus Clostridium.