JPH0468912B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to immobilized microorganisms. More specifically, the present invention relates to an immobilized microorganism characterized by using cellulose acetate porous particles as a carrier for immobilization. (Conventional technology) Research on immobilized microorganisms has become more and more popular in recent years, and is beginning to attract attention as an industrially important technology. Various methods have been known for producing immobilized microorganisms, and a typical method is to enclose and immobilize microorganisms in a gel made of polyacrylamide, alginic acid, carrageenan, polyvinyl alcohol, etc. Are known.
(“Fixed Oxygen” edited by Ichiro Chibata, Kodansha 1975). Among them, the method using alginic acid and carrageenan is a simple method for producing immobilized microorganisms, and is widely used because it can be used for immobilizing various microorganisms. (Problems to be Solved by the Invention) However, in the methods using these gels, if the commonly used heat sterilization conditions are applied, the strength of the gel obtained may decrease or the growth of microorganisms within the gel may occur. In addition, it is necessary to cause a microbial reaction in the presence of gelling agents such as calcium ions and aluminum ions, and degelling agents such as phosphate ions are also present. In some cases, when gel dissolution occurs, furthermore, when organic acids are produced by microbial reactions, they are inevitably in the form of their calcium salts or aluminum salts, such as when obtaining sodium salts of organic acids. There were serious industrial problems such as the impossibility of methods using these gels. (Means for Solving the Problems) The present inventors have conducted various studies in order to overcome the basic drawbacks of alginic acid, carrageenan, etc. that have been conventionally used as immobilization carriers, and have found that cellulose acetate can be used as an immobilization carrier. It was discovered that the above-mentioned drawbacks could be overcome by using porous particles, as it is easy to immobilize microorganisms, heat sterilization is possible, the carrier strength is high, and it can be used in the presence of a degelling agent. The invention has been completed. That is, the present invention provides an immobilized microorganism in which microorganisms are immobilized on cellulose acetate porous particles having specific physical properties. As the cellulose acetate used in the present invention, cellulose acetate having a degree of acetylation of 48 to 62% and having a hydroxyl group and an acetate ester group is suitable.
155245), porous particles can be obtained by extruding a solution of cellulose acetate, such as acetone or acetic acid, into a suitable coagulating solvent, such as an aqueous ascent solution or an acetic acid solution, coagulating it, and washing it with water. Particles can take various shapes such as granules, spheres, cylinders, and oval shapes, but spherical shapes are
It is advantageous in terms of fluidity, strength, surface area, etc., and the particle size is preferably 0.5 to 10 mm. Cellulose acetate porous particles produced by this method have high crushing strength in spite of their large pore volume. The particles used in the present invention are porous particles with a pore volume of 0.65 cc/g or more and a crushing strength of 10 kg or more, and a pore distribution width of about 75〓 to 10μ, and the pore size can be adjusted by changing the concentration of the coagulating solvent, such as an acetic acid aqueous solution. Although some of these pores include closed cells, most of them form open cells. The cellulose acetate used is cellulose acetate with an acetylation degree of 40 to 62%, more preferably 48 to 58%, which has an appropriate balance of hydrophilic and lipophilic groups to strengthen immobilization. It is thought that there is. In addition, continuous pores are formed with fine pores and pores of several micrometers in size, which together with the above-mentioned balance of hydrophilic groups and lipophilic groups are thought to have the effect of improving the growth of immobilized microorganisms. . Pore volume
If it is less than 0.65 cc/g, the amount of microorganisms supported is too small to be practical. Also, if the crushing density is less than 10 kg, the particles may break during use, making it impractical.
Also, if the particle size is less than 0.5 mm or more than 10 mm, there will be problems with cleaning during production, but if necessary, the cellulose acetate porous particles may be crushed to destroy the skin layer or the particle size may be reduced to 0.5 mm or less. can be used. The microorganisms used in the present invention are classified into molds, yeasts, bacteria, actinobacteria, and the like. These microorganisms are grown in a nutrient medium and then used in a live state. To explain the present invention in more detail, for example, cellulose acetate porous particles are added to a medium prepared by a conventional method and then heat sterilized.
Cellulose acetate porous particles are stable even at 250°C, so there are no problems at 120°C, which is the general sterilization temperature. Thereafter, the desired immobilized microorganism can be obtained by simply inoculating the microorganism to be immobilized and culturing in the usual manner, since the microorganism will grow even within the cellulose acetate porous particles. More preferably, by keeping the culture solution under reduced pressure after inoculating the microorganisms, migration of the microorganisms into the cellulose acetate porous particles can be promoted. Furthermore, the immobilization time can be further shortened by preparing a concentrated microbial suspension by centrifuging the culture solution obtained by conventional culture, adding sterilized cellulose acetate porous particles to the suspension, and maintaining the suspension under reduced pressure. The immobilized microorganism thus obtained can be subjected to the desired reaction using a general stirring mixing tank or a packed column type reactor. [Example] The present invention will be further explained with reference to Examples below.
The present invention is not limited to these examples. Example 1 Sporolactobacillus inulinus TUA343L was cultured in the liquid medium shown in Table 1 at 37°C for 24 hours.
20ml of this culture solution was sterilized at 120℃ for 15 minutes (cellulose acetate porous particles shown in Table 2).0.25
g was added aseptically and maintained under reduced pressure (40 mmHg) for 2 hours. Next, the cellulose acetate porous particles were taken out from the culture solution, washed with water, and transferred to 140 ml of the glucose medium shown in Table 1 to produce lactic acid at 37° C. while stirring. Thereafter, the cellulose acetate porous particles were taken out at regular intervals, washed with water, and the reaction was repeated in the same manner. As is clear from the results shown in Table 2, it is clear that cellulose acetate porous particles are an effective immobilization carrier for microorganisms.

【table】 Table-2 Properties of cellulose acetate porous particles Acetylation degree 54.8% Pore volume 0.9c.c./g Pore distribution width 75Å~8μ Crushing strength 13Kg Particle size 5.0mm

【table】

Claims (1)

[Claims] 1. Microorganisms are immobilized on cellulose acetate porous particles with an acetylation degree of 40 to 62%, a particle diameter of 0.5 to 10 mm, a pore volume of 0.65 cc/g or more, a crushing strength of 10 kg or more, and a pore distribution width of 75 to 10 μ. immobilized microorganisms.