JPS5910795B2 - Alcohol production method by fermentation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing alcohol by fermentation. In recent years, fermented alcohol, which can be obtained without using petrochemicals, has been in the spotlight as an energy alternative to petroleum.

This is sugar cane, molasses, sweet potato,
It is produced by fermenting cellulosic or starchy materials such as potatoes and corn through the action of bacterial cells.

In this method, alcohol productivity is thought to depend on the bacterial cell concentration.

Therefore, in order to increase the bacterial cell concentration, a method of circulating the bacterial cells and a so-called immobilized cell growth method in which yeast is encapsulated in a polysaccharide-based substance are being developed.

However, in the former case, the centrifugal separator used to concentrate and separate the bacterial cells becomes clogged or nozzles clogged by the solids present in the culture solution, making it increasingly difficult to circulate the bacterial cells.

Therefore, it is necessary to periodically clean the centrifuge, which makes the work extremely troublesome.

In the latter case, for mass production on an industrial scale,
There are many problems that are technically difficult to solve.

In view of these circumstances, the present inventor has conducted extensive research to increase the concentration of microbial cells in the fermenter, and as a result has completed the present invention.

That is, the present invention is a method for producing alcohol by fermentation, which is characterized by using crushed porous vermiculite as a medium for bacterial cell attachment in a fermentation tank.

In addition to crushed porous vermiculite, sand, activated carbon, zeolite, and the like may be used as a medium for bacterial adhesion, and these were also considered.

The results are as follows. In other words, sand has poor dispersibility and requires a large amount of power to uniformly disperse it.

Furthermore, in the case of activated carbon and zeolite, their strength is inferior, so they are subject to significant wear due to mechanical dispersion.

On the other hand, crushed porous vermiculite is highly dispersible and has excellent abrasion resistance, making it optimal as a medium for bacterial adhesion.

As the porous crushed vermiculite, one formed by dehydrating raw stone by heat treatment or the like and then crushing it is often used, but it is not limited thereto.

This pulverized material has excellent dispersibility and abrasion resistance because it forms ultra-thin flakes, and also has a large specific surface area, so that a large amount of bacterial cells can be attached thereto.

As a sample strain of Example, Saccharomyces cerevisiae sp.
AE spec-ies), porous vermiculite crushed to 60 to 80 mesh was used as a medium for bacterial cell attachment, and 10 wt/v% of the bacterial strain and support were introduced into a fermentation tank.

The fermentation tank used was one equipped with a sedimentation section or a separation means provided at the upper part of the tank for the purpose of separating the crushed vermiculite.

The composition of the medium is glucose 150 f/mu yeast extract 3.0? /t, NH4Cl 2.0f/l, KH2P
O40.8f/t, MgCl2・6H20 0.2? /
t and CaCl20.1, and this medium also contains silicone (Toshiba Silicone) 0.1?2 as an antifoaming agent. /
1 was added.

Fermentation conditions were pH=5, temperature=30℃, and aeration rate=0.0.
2-0. The dilution rate was approximately 1 vvm and the dilution rate was 0.2/hour.

Continuous culture was carried out under these conditions, and ethanol was produced at a productivity of 1
Obtained at 4f/l·hr.

In addition, Zymomonas mobilis (Zymomonas mobilis) was used as a test bacterial strain.
monas mobilis) IFO/ 3 7
The above operation was repeated using 56.

However, the fermentation conditions are pH = 4, no aeration, dilution rate 0.5.
It was set at 7 o'clock.

As a result, the productivity of ethanol is approximately 3 5 fi-/,
It was l.

In this way, the productivity of bacteria has been significantly improved compared to yeast.

The reason for this is thought to be that bacteria are relatively small, so they adhered to the porous vermiculite and multiplied in large quantities.

Furthermore, the same procedure as above was performed for lactic acid bacteria, butanol bacteria, etc., and the productivity was significantly improved in all cases.

On the other hand, in the basic continuous culture method that does not use a medium for bacterial adhesion, the ethanol productivity is 2 to 3? /t hours.

Thus, according to the present invention, productivity can be significantly improved.

Claims (1)

[Claims] 1. A method for producing alcohol by fermentation, characterized in that porous crushed vermiculite is used as a medium for bacterial adhesion in a fermentation tank.