JPH0799960A - Ceramic carrier for bioreactor - Google Patents

Abstract

PURPOSE:To obtain a ceramic carrier in which an organic thin film stably fixing a microorganism or an enzyme for a long period is set to a ceramic honeycomb carrier or a porous ceramic carrier used in chemical reactions. CONSTITUTION:In place of the conventional ceramic carrier having a smooth surface, this ceramic carrier is obtained by densely modifying the surface of a bead-, pellet- or horse-hoof-shaped ceramic carrier with needle or prismatic mullite crystals each having 1 to 100mum length and 0.1 to 10mum thickness in a lawn state and subsequently embedding a cross-linked chitosan film between the mullite crystals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for immobilizing microorganisms and enzymes on a ceramic honeycomb carrier or a porous ceramic carrier used in a chemical reaction for a long period of time and stably.

[0002]

Biochemical reactions utilizing enzymes and microorganisms are widely used in the fields of foods, pharmaceuticals and the like. Conventionally, as a method for immobilizing enzymes and microorganisms on the surface of a ceramic carrier, a physical adsorption method in which the enzyme is directly adsorbed on the surface of the carrier, a covalent bond method for covalently bonding an enzyme and a microorganism to a water-insoluble bead-shaped or pellet-shaped carrier surface, There is a crosslinking method in which a carrier is crosslinked with a carrier using a crosslinking agent such as glutaraldehyde or bisdiazobenzidine.

[0003]

However, in the conventional physical adsorption method, since the adhesive force between the carrier and the enzyme is weak, the enzyme is easily separated from the carrier during the reaction, and high reaction activity cannot be expected. In addition, the covalent bond method, the cross-linking method, etc. also have a problem in that the microorganisms are remarkably altered and deteriorated by immobilization to cause a decrease in reaction activity. Furthermore, the covalent bond method has a problem that the amount of immobilized enzyme is limited.

[0004]

DISCLOSURE OF THE INVENTION The present invention develops a ceramic carrier having a high adhesion strength with a ceramic carrier and having a stable organic thin film on the surface for a long period of time such that enzymes and microorganisms will not be altered or deteriorated by time-bearing treatment. Is. The present invention is
Instead of a conventional ceramics carrier with a smooth surface, the surface of the ceramics carrier has a length of 1 to 100 μm and a thickness of 0.1.
It is a carrier having a porous tissue structure in which needle-like or columnar mullite crystals of 10 μm are modified at high density into a lawn shape. The present invention provides a ceramics carrier which is excellent in the permeability of a liquid substance and can carry a thin film having high adhesion strength on the surface.

In the present invention, first, a ceramic carrier is immersed in an acetic acid solution containing chitosan whose molecular weight is reduced by hydrogen peroxide, and then chitosan is solidified with a potassium hydroxide solution, and then a chitosan film cross-linked with glutaraldehyde is formed. Since it is a ceramics carrier, a carrier with excellent adhesion and amount of enzymes and microorganisms was obtained.

In the case of the present invention, the surface of the ceramics carrier is in the shape of a lawn with numerous fine mullite crystals. Therefore, the chitosan thin film easily penetrates between the individual mullite crystals, and because the chitosan thin film is embedded between the crystals, an organic film that is difficult to peel off from the ceramic carrier could be obtained. In the conventional ceramic carrier, the surface of the carrier is smooth and the permeability of the film into the carrier is very low, so the peel strength of the film is reduced.

[0007]

Example 1 With a hydrogen peroxide of 0.03%, a molecular weight of 10,
000-20,000 low molecular weight chitosan 1.
40% porosity in 1.0% acetic acid solution containing up to 5% concentration,
An alumina porous body having a pore diameter of 0.6 μm was immersed while degassing for 30 minutes. Then, it was immobilized with a 5% potassium hydroxide solution, and further crosslinked with 5% aldehyde to carry out a chitosan film on the surface of the porous ceramics. By repeating the above operation and increasing the number of times of dipping in the chitosan solution, the film thickness of chitosan could be changed to 10 to 1000 μm. Furthermore, by changing the chitosan solution in the range of up to 10%, it was possible to increase the film thickness up to 3 mm. Thickness 1 supported on porous alumina
The adhesion strength of 0-100 μm chitosan film is 6-8 kg /
It was cm2.

Example 2 A clay mineral containing alumina or silica was molded into a honeycomb shape, dried, and then fired at 1400 to 1700 ° C. to prepare a honeycomb ceramic. In this honeycomb, silica glass soluble in acid or alkali and mullite insoluble in acid or alkali are present.
When the surface layer is chemically etched with ˜9.2% hydrofluoric acid, the surface has a length of 1 to 100 μm and a thickness of 0.1 to 10 μm.
Needle-shaped or columnar mullite crystals of μm are exposed like grass. The structure composed of individual mullite crystals has a porous structure and has numerous pores with a diameter of 0.1 to 1.0 μm.
The adhesion strength of the chitosan thin film having a thickness of about 10 to 100 .mu.m, which was carried by the method of Example 1 on the ceramic carrier having the porous texture structure, was 12 to 20 kg / cm @ 2. On the other hand, the adhesion strength of the chitosan thin film supported by the same chemical treatment on a smooth ceramics carrier surface not subjected to etching treatment was 0.5 to 2.0 kg / cm @ 2.

Example 3 Glucoamylase was adsorbed and immobilized on the surface of the honeycomb-shaped ceramic carrier coated with chitosan prepared in Example 2, and 10 g / l of starch was used as a substrate at a solution temperature of 50 ° C. and a pH of 4.5. The batch and flow reaction experiments were carried out and the glucose concentration produced was measured by the enzymatic method.
First, in a batch reaction experiment using immobilized enzymes prepared by immersing carriers with different chitosan loadings in enzyme solutions of the same concentration, the initial reaction rate increased almost linearly with the increase in chitosan weight, and the film thickness increased. I confirmed the merits of making it. Further, in the flow-type reaction experiment in which the residence time of the reaction solution was changed within the range of 0.5 to 2 hours, the conversion rate to glucose was able to achieve 50 to 95%. The reactor activity could be increased at least 5-fold or more by increasing the concentration of the enzyme solution used for immobilization.
In addition, the half-life of the reactor activity during the flow-through reaction was about 3 days in the case of unmodified chitosan because the elimination of the enzyme gradually occurred, but the tertiary amine and quaternary amine were introduced into this This dramatically improved the activity and stabilized the activity so that the half-life could not be estimated. Furthermore, peeling of the chitosan film did not occur even after continuous use for one month or more, and it was confirmed that one end of the chitosan film was embedded and stabilized in the acicular mullite crystals on the surface of the ceramic carrier.

Claims (2)

[Claims] 1. A ceramic carrier having a chitosan film obtained by immersing the ceramic carrier in an acetic acid solution containing chitosan having a low molecular weight with hydrogen peroxide, immobilizing the chitosan with a potassium hydroxide solution, and then cross-linking with glutaraldehyde. . 2. A needle-shaped or column-shaped mullite crystal having a length of 1 to 100 μm and a thickness of 0.1 to 10 μm on the surface of a bead-shaped, pellet-shaped, horseshoe-shaped ceramic carrier or a ceramic monolith having a honeycomb structure. A long-term stable bioreactor carrier in which a chitosan film is embedded between crystals after being grown at high density.