JPS61124374A - Method of cultivating microorganism to form methane from acetic acid - Google Patents

Abstract

PURPOSE:To cultivate the titled microorganism industrially efficiently, by detecting rise in pH caused by consumption of acetic acid resulting from fermentation in a medium containing an acetate mixed with a methane producing microorganism, neutralizing the medium with acetic acid, and keeping the pH at the fittest value. CONSTITUTION:A medium containing growth factors such as an N source, a phosphoric acid source, an S source, mineral, vitamin, etc. and an acetate is used, a culture container is filled with an anaerobic gas atmosphere such as N2, etc., the medium is mixed with a methane producing mold, a microorganism to form methane from acetic acid is fed to the medium, and cultivation is started at a temperature suitable for growth at the fittest pH. Then, as the cultivation is advanced, the microorganism is multiplied and acetic acid is consumed, the rising pH value is detected by a pH sensor, acetic acid is dropped to keep the fittest pH condition, and the cultivation is continued efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a culture method for efficiently culturing microorganisms that produce methane from acetic acid.

Conventional technology The main reaction route of methane fermentation is as follows.

The organic matter that serves as the raw material for fermentation mainly produces acetic acid, hydrogen, and carbon dioxide gas through the catabolic metabolism of common microorganisms. Of these, hydrogen and carbon dioxide are converted to methane by methane-producing bacteria. Acetic acid also turns into methane through the action of microorganisms, but many aspects of the microorganisms that carry out this reaction remain unclear.

Problems to be Solved by the Invention In the conventional methane fermentation method, these microorganisms grow naturally in the fermenter, but it is difficult to handle these microorganisms as they are. That is,
The environments in which these microorganisms live are all muddy environments that contain a large amount of solid matter, and this solid matter means that the volume to be handled becomes large. In addition, there is a long need to handle, for example, the supply of methane-fermenting microorganisms to newly installed fermenters, and for this purpose, methane-fermenting microorganisms are extracted either in pure form or in the form of priority species through enrichment culture, and used for industrial purposes. There is a movement to obtain a rich concentration of microorganisms by culturing them, but this is not easy because the cultivation efficiency of microorganisms that produce methane from acetic acid is particularly low.

The present invention provides a method for efficiently culturing microorganisms that produce methane from acetic acid, thereby contributing to the industrial production of methane-fermenting microorganisms.

Means for Solving the Problems The present invention is capable of solving the problems by mixing methane-producing bacteria into the culture medium.
Based on a known technology that promotes the growth of microorganisms that produce methane from acetic acid, we used a medium containing acetate mixed with methane-producing bacteria, detected the increase in pH due to consumption of acetic acid, and neutralized it with acetic acid. The method involves culturing microorganisms that produce methane from acetic acid while maintaining optimal pH conditions.

Effect: According to the above-mentioned means, acetic acid is added dropwise as the microorganisms that produce methane grow, thereby replenishing the energy for the microorganisms' growth.

Example Examples of the present invention will be described below.

Table 1 shows an example of the liquid culture medium used in the present invention. Nitrogen source, phosphoric acid source, sulfur source, mineral.

Using a medium containing growth factors (vitamins, etc.) and acetate,
The gas phase in the culture container is replaced with anaerobic gas such as nitrogen gas to create anaerobic conditions, and methane-producing bacteria are mixed with this.
Furthermore, microorganisms that produce methane from acetic acid (currently, pure isolation has not been successful, so microorganisms enriched by enrichment culture can be used) are inoculated and culture is started. As the culture temperature, use the optimum temperature for growth. The optimum pH for growth is also used as the initial culture pH. All of these differ depending on the microbial strain and cannot be described uniformly.

Now, l increases as the culture progresses. The reason for this can be understood from the following equation.

+ OHC00M+H-CH+GO+M+ S 4
2 Here, M+ represents a base. That is, the pH increases because acetic acid groups are consumed as microorganisms that produce methane from acetic acid proliferate. Due to this increase in pH, the growth pH of living organisms that produce methane from acetic acid deviates from the optimum conditions. This pH increase is detected using a pH sensor, and the optimum pH condition is maintained by dropping acetic acid. Also, the dropped acetic acid is consumed in the same way as acetate, and serves to supply energy for the growth of microorganisms that produce methane from acetic acid.

Table 1 Effects of the Invention As described above, according to the present invention, it is possible to continue culturing for a long period of time while maintaining the optimum pH conditions for growth, and it is possible to supply a large amount of energy necessary for proliferation. Microorganisms that produce methane can be efficiently cultured, and microbial cells with a high concentration can be obtained.

Claims (1)

[Claims] Using a medium containing acetate mixed with methane-producing bacteria, we measured the increase in pH due to the consumption of acetic acid by microorganisms that produce methane from acetic acid, and then neutralized it with acetic acid to maintain the pH condition at an optimal value. Cultivation method for the microorganisms produced.