JPS6075289A - Method for preventing contamination of fermentation liquid with sundry germ in production of alcohol by continuous fermentation - Google Patents

Abstract

PURPOSE:To prevent the contamination of the fermentation liquid with sundry germs in the continuous fermentation of a saccharide raw material to produce an alcohol, by adding air and an agent to prevent the contamination with sundry germs to the fermentation liquid. CONSTITUTION:A saccharide raw material such as waste molasses and water are supplied to the conditioning tank 1, and a fermentation liquid is prepared by adjusting the concentration of the mixture to the optimum level for fermentation. The fermentation liquid is introduced continuously into the fermentation tank 2 containing proliferated yeast cells. In the line to pass the fermentation liquid to the tank, 100-1,000mg of an agent to prevent the contamination with sundry germs, e.g. sodium metabisulfite, is added to 1 liter of the fermentation liquid. At the same time, aseptic air is introduced into the fermentation tank 2 to suppress the proliferation of anaerobic germs. The alcohol produced from the fermentation liquid with yeast in the fermentation tank 2 is taken out of the tank continuously.

Description

[Detailed Description of the Invention] Ethanol production by fermentation of biomass is attracting attention as an alternative energy source to petroleum.

As raw material biomass, starchy substances such as molasses and potatoes, and cellulosic substances such as straw and bagasse are used.

These basically belong to sugars. In recent years, with the aim of increasing alcohol production efficiency and reducing alcohol production costs, research and development of alcohol production methods using continuous fermentation have been progressing. One of the challenges in this research and development is to prevent contamination of the fermentation liquid by bacteria. In the case of batch fermentation, even if the fermentation liquid is contaminated with bacteria, the loss is only for that batch, and if sterilization is performed again, normal operation is possible from the next time, whereas in continuous fermentation Once the fermentation liquid becomes contaminated, it is difficult to restore it to its normal state. For this reason, there are strict sterilization methods in which the raw materials are heated and sterilized in advance, but in the production of alcohol as an alternative energy source to petroleum, energy conservation in the production process is an important issue.
Heat sterilization methods that require thermal energy are not preferred. In addition, in the case of this sterilization method, the raw materials after sterilization must be cooled before being fed to the fermenter, and as there is a risk of contamination with various bacteria, sufficient management is required to avoid contamination with contamination. became troublesome.

In view of the above-mentioned points, the present inventors have conducted extensive research to provide a method for preventing bacterial contamination that is advantageous in terms of energy and cost and can be achieved with simple operations. The present invention was completed based on the knowledge that yeast and bacteria are facultative anaerobic microorganisms, whereas many of the bacteria that cause a decrease in alcohol production yield are obligate anaerobic bacteria. .

The method for preventing bacterial contamination according to the present invention is characterized by adding air and a bacterial contamination preventive agent to the raw material and/or fermentation liquid when producing alcohol by continuous fermentation of carbohydrate raw materials using microorganisms capable of fermenting alcohol. That is.

Metabisulphites, such as potassium metabisulphite, are suitable as antimicrobial agents. Sodium hypochlorite can also be used. If the amount of the bacterial contamination preventive agent added is too large, the fermentation itself will be inhibited, and if it is too small, the effect of preventing bacterial contamination will not be achieved. Preferable addition 1 is raw material II adjusted to a concentration suitable for fermentation! 100-1000m9 per
It is.

Air acts to prevent the growth of anaerobic bacteria. The air blowing mother is not particularly limited, but the fermenter volume II! Normally the hit is about 0.141! /minute.

Known microorganisms having alcohol fermentation ability are used; a representative example thereof is Zymomonas mobilia medium and fermentation condition 1, which is a normal medium and conditions for alcohol production from sugars. Each applies. The fermentation temperature is 25-32℃, preferably around 30℃, and the pH is 4-32℃.
6, preferably around 5.

Glucose, sucrose, galactose, etc. are used as carbohydrate raw materials.

As described above, according to the method for preventing bacterial contamination of the present invention,
Since air and a microbial contamination preventive agent are added to the raw materials and/or the fermentation liquor, contamination of the fermentation liquor by germs can be reliably prevented at low cost during continuous fermentation.

Next, the present invention will be specifically explained with reference to illustrated embodiments.

Example In FIG. 1, blackstrap molasses is used as the carbohydrate raw material, and this and water are supplied to the adjustment tank (1) to adjust the mixture to the optimum concentration for fermentation. Next, the adjusted raw material is transferred to a fermenter (2)
Continuously leads to. Sodium metabisulfite is then added as a contamination inhibitor to the prepared raw material on the inlet to the fermenter (2). The amount of addition is about 500 to 500 potassium metabisulfite per 11 of the prepared raw materials. Furthermore, air is blown into the fermentation tank (2) to suppress the growth of obligate anaerobic microorganisms within the tank. Fermentation is carried out in this manner, and a fermented liquid containing alcohol produced from the carbohydrate raw material is taken out from the tank.

In experiment Figure 2, the total sugar concentration was 1609 as the carbohydrate raw material.
Using blackstrap molasses whose concentration was adjusted to 1.2 ml of ammonium sulfate.
8 P/l was added to the bottom of a glass fluidized bed fermenter (3) with an actual volume of 0°71. Air is also blown into the bottom. The amount of air blown is 0.1 air per 11 volumes of the fermenter.
4//min.

Zymomonas mobilis and flocculating yeast are used as microorganisms having alcohol fermentation ability. Fermentation is carried out in this manner, and the ethanol concentration of the resulting fermented liquid is measured. The measurement results are shown in Figure 3.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram showing a method for preventing bacterial contamination, FIG. 2 is a schematic diagram showing a fermenter, and FIG. 3 is a graph showing the relationship between operation time and ethanol concentration.

Claims (1)

[Claims] (1) In producing alcohol by continuous fermentation of carbohydrate raw materials using microorganisms having alcohol fermentation ability,
A method for preventing bacterial contamination of a fermentation liquor in alcohol production by continuous fermentation, which comprises adding air and a germ contamination preventive agent to raw materials and/or fermentation liquor. (2) The method according to claim 1, wherein the bacterial contamination preventive agent is potassium metabisulfite.