JP2731074B2 - Acetic acid production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing acetic acid, one of useful acids.

[0002]

2. Description of the Related Art Clostridium thermoaceticum is a thermophilic anaerobic bacterium that is generally known to produce 3 mol of acetic acid from 1 mol of glucose as shown in the following reaction formula. Have been. C ₆ H ₁₂ O ₆ → 3CH ₃ COOH ...

[0003]

However, Clostridium thermoaceticum (Clostridium thermoaceticum)
um) was cultured in an absolute anaerobic condition using only glucose as a substrate to produce acetic acid, which had the disadvantage of increasing the cost. SUMMARY OF THE INVENTION It is an object of the present invention to produce acetic acid with inexpensive materials using Clostridium thermoaceticum.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing Clostridium thermoaceticum, which is a homoacetic acid bacterium, by using a complex substrate containing glucose, methanol and a carbon dioxide gas as main components.
It has been found that acetic acid is produced, and the characteristic means of the method for producing acetic acid in the present invention is that Clostridium thermoaceticum is subjected to absolute anaerobic conditions and contains glucose, methanol and carbon dioxide as main components. In this method, the treated liquid after the culture is subjected to solid-liquid separation to take out the separated liquid, and acetic acid is collected from the separated liquid, and the operation and effect are as follows.

[0005]

[Effect] Clostridium thermoreseticum (Clos
When tridium thermoaceticum) is cultured in a strictly anaerobic condition with a composite substrate mainly composed of glucose, methanol and a carbon dioxide gas source, acetic acid is also produced from methanol and carbon dioxide gas in the presence of glucose. That is, the stoichiometric formula is as follows: C ₆ H ₁₂ O ₆ + 4CH ₃ OH + 2CO ₂ → 6CH ₃ COOH + 2H ₂ O. From the above formulas and formulas, 4 moles of methanol and 2 moles of carbon dioxide contribute to 3 moles of acetic acid. It is thought that it is.

[0006]

Thus, acetic acid can be produced by culturing with a composite substrate mainly composed of glucose, methanol and a carbon dioxide gas source instead of the conventional substrate consisting of solely glycol, so that methanol and glucose can be used as substrates. A carbon dioxide gas source can be used, and production cost can be reduced by using waste methanol discharged from a chemical plant or the like and CO ₂ in the atmosphere as a raw material for acetic acid production. Accordingly, there is obtained an effect that it is effective for effective recycling of waste and reduction of atmospheric CO ₂ .

[0007]

Next, embodiments of the present invention will be described. Clostridium thermoac
eticum) ATCC 31490 with at least carbon (C),
In a medium containing potassium (K), phosphorus (P), sulfur (S), magnesium (Mg) and nitrogen (N), the gas phase is degassed with CO ₂ , and glucose, methanol and carbon dioxide gas are removed. The culture temperature was 55
C., normal pressure, pH 7.0-7.7, cultivated under culturing conditions of absolute anaerobic state, acetic acid was generated, the treated solution after culturing was fixed and separated, the separated solution was taken out, and acetic acid was collected from the separated solution. .

[Experimental Example 1] Based on the medium composition shown in Table 1 below,
The mixture molar ratio of glucose and methanol in the medium is 10:
It adjusted to 0,7: 3,5: 5,3: 7,0: 10, and culture | cultivated respectively.

[0009]

Table 1 Composition of LS medium (per liter of deionized water) Glucose 20.0 g Yeast extract 5.0 g Tryptone 5.0 g (NH ₄ ) ₂ SO ₄ 1.0 g Co (NO ₃ ) _{2 · 6H 2 O 0.029g Fe (} NH 4) 2 (SO 4) 2 · 6H 2 O 0.039g Na 2 MoO 4 · 2H 2 O 0.12 g CaCl 2 · 2H 2 O 0.021g thioglycolic acid Sodium 0.5 g NaHCO ₃ 16.8 g K ₂ HPO ₄ 7.0 g KH ₂ PO ₄ 5.5 g L-cysteine hydrochloric acid solution 0.3 g Trace metal solution 10 ml MgSO ₄ .7H ₂ O 0.25 g

The trace metal solution in Table 1 contains the following components in one liter. MnCl ₂ .4H ₂ O 0.5 g Na ₂ SeO ₃ 17.2 mg H ₃ BO ₃ 10 mg ZnCl ₂ 5 mg AlK (SO ₄ ) ₂ .12H ₂ O 10 mg NiCl ₂ .6H ₂ O 2 mg CuCl ₂ .2H ₂ O 1 mg Na ₂ -EDTA 0.5 g Table 2 shows the culture results of each medium, and FIG. 1 shows changes in various measured values depending on the culture time of each medium.

[0011]

[Table 2]

The amount of the cells was examined by a dry weight method, and the amount of acetic acid was measured by gas chromatography (FID). From Table 2 and FIG. 1, simultaneous consumption of glucose and methanol was observed in the medium using glucose, methanol and an acetic acid gas source as a composite substrate, and the stoichiometry of the above formula was determined from the amount of acetic acid produced, the amount of glucose consumed, and the amount of methanol consumed. The formula holds. However, the growth of the bacteria and the production of acetic acid were not observed from the medium using only the methanol and carbon dioxide gas as the composite substrate. From the above, it was clarified that methanol and carbon dioxide gas were acetic acid in the presence of glucose. In addition, as in the case of glucose, a small amount of extracellular 5-aminolevulinic acid (ALA) was produced even without the inhibition of 5-aminolevulinic acid (ALA) dehydratase (for example, levulinic acid). It can be seen that 5-aminolevulinic acid (ALA) increases as the molar ratio of the mixture increases. The collected 5-aminolevulinic acid (ALA) was confirmed by identification by thin layer chromatography (TLC) as shown in FIG.
It was measured by colorimetry using the all and Granick method.

[Another embodiment] Clostridium thermoaceticum ATCC3
1490 is filled with N ₂ gas in the gas phase in the same medium as described above, and the culture temperature is 55 ° C., normal pressure, pH 7.5 to 8.0.
0, the culture was performed under culture conditions of absolute anaerobic state, but no growth of bacterial cells and no production of acetic acid were observed in each medium. From the above results, it is considered that carbon dioxide gas is necessary for acetylation of glucose.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 Changes in various measured values based on time changes

FIG. 2. Thin layer chromatography to identify ALA

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shiro Nagai 16-7-610 Furuenishi-cho, Nishi-ku, Hiroshima City, Hiroshima Prefecture

Claims (1)

(57) [Claims] 1. Clostridium thermoaceticum is cultivated in an absolute anaerobic state with a composite substrate containing glucose, methanol and carbon dioxide as main components, and the treated liquid after culturing is separated into solid and liquid. A method for producing acetic acid, in which a separated solution is taken out and acetic acid is collected from the separated solution.