JPH0813250A - Production of chitosan/chitin-based hollow fiber - Google Patents

Abstract

PURPOSE:To obtain a chitosan/chitin-based hollow fiber having antimicrobial and absorbing functions and not substantially containing glucan by subjecting a bacterial cell of the genus Rhizopus cultured under acidic conditions to thermal alkali treatment. CONSTITUTION:An aqueous solution of sodium hydroxide in an amount of 0.5-5wt.% is added to Rhizopus acetoinus HUT 1219 bacterium cultured under an acidic condition of pH4.0 to 6.0 and the bacterial cell is subjected to thermal alkali treatment at 80-150 deg.C in an autoclave and insoluble solid material is separated and the cultured product is washed with water and lyophilized to provide a chitosan/chitin substantially not containing glucan. The objective hollow fiber is formed by using this chitosan/chitin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel method for producing a chitosan-chitin hollow fiber derived from a microorganism. More specifically, the present invention relates to a method for efficiently producing a chitosan-chitin-based hollow fiber substantially free of glucan, which is useful as a functional material, from cultured cells of a genus Rhizopus.

[0002]

2. Description of the Related Art Chitin has the general formula

Embedded image Is a kind of polymeric polysaccharide composed of N-acetylglucosamine units, and chitosan is a partial deacetylated product of this chitin. Chitin is contained in large quantities in the shells of crustaceans such as crabs and shrimps, and in the cell walls of some microorganisms, for example, the genus Rhizopus, which is one of the filamentous fungi.

In recent years, since various physical and physiological functions of chitin and chitosan have been found, application studies thereof have been actively conducted. For example, as natural flocculants, adsorbents, enzyme immobilizing agents, Furthermore, antibacterial and deodorant imparting agents in the fields of textiles and clothing, rooting of plants in the field of agriculture, activators of defense functions against growth promoters and pathogens, wound covering protection materials in the medical field, moisturizers in the cosmetic field, and in the food field It is expected as a health food material.

By the way, it is known that a hollow fiber mainly composed of the cell wall of the Rhizopus bacterium is treated with hot alkali to obtain a hollow fiber, and the main components of this are chitosan, chitin and It is also known to be a glucan (JP-A-55-9691 and JP-B-5-273253). Such hollow fibers can be easily molded into sheets, films, filters, etc. having antibacterial and adsorptive properties, and functional products such as drugs, enzymes and bioactive substances can be added to these molded products However, since it can have various functionalities, it is expected to be applied as a new material.

However, when the Rhizopus cells cultured by the usual method are treated with hot alkali, the resulting hollow fibers contain about 20% by weight of glucan in addition to chitosan and chitin. Since glucan contributes little to the functionality of the hollow fiber, in order to further improve the functionality of the hollow fiber, it is desirable to reduce the content of glucan as much as possible and improve the content of chitosan and chitin. .

[0006]

Under the above circumstances, the present invention provides a functional material having a high content of chitosan and chitin, which is substantially free of glucan, from cultured cells of Rhizopus. The purpose of the present invention is to provide a method for efficiently producing a useful chitosan-chitin-based hollow fiber.

[0007]

Means for Solving the Problems As a result of intensive studies to obtain chitosan-chitin-based hollow fibers containing no glucan, the present inventors have shown that by culturing Rhizopus in a specific pH range, The biosynthesis of glucan in the cell wall is strongly suppressed, the biosynthesis of chitosan and chitin is activated, and the treated bacterial cells are treated with hot alkali, and the chitosan and chitin content is substantially free of glucan. Finding that hollow fibers with a high rate can be obtained,
Based on this finding, the present invention has been completed.

That is, the present invention has a pH of 4.0 to 6.0.
The present invention provides a method for producing a chitosan-chitin-based hollow fiber substantially free of glucan, which comprises subjecting Rhizopus cells cultured under the conditions described above to hot alkali treatment.

The Rhizopus genus used in the method of the present invention is one type of filamentous fungus, and the strain species is not particularly limited, and various types can be used. Examples of the bacterium of the genus Rhizopus include Rhizopus acetoinus HUT12
19 bacteria can be mentioned.

In the method of the present invention, the culture of Rhizopus is pH 4.0-6.0, preferably 4.5-5.
It is necessary to carry out in the range of 8. If this pH is less than 4.0 or more than 6.0, suppression of glucan biosynthesis and activation of chitosan and chitin biosynthesis become insufficient,
The object of the present invention cannot be fully achieved.

The culture method is not particularly limited, and either a liquid culture method or a solid culture method can be used, but the liquid culture method is preferable. As the liquid culture method, a surface culture method and a submerged culture method can be used, and a batch culture method or a continuous culture method may be used. The culture temperature is usually selected in the range of 20 to 40 ° C.

After the completion of the culture, the bacteria are collected by filtration or centrifugation, and then subjected to a hot alkali treatment. This hot alkali treatment is usually carried out by treating the cultured cells in an aqueous solution containing about 0.5 to 5% by weight of a hydroxide of an alkali metal such as sodium hydroxide or potassium hydroxide to give the cultured cells of 80 to
It is carried out by heating at a temperature in the range of 150 ° C. The treatment time depends on the concentration of the alkali, the treatment temperature, etc. and cannot be determined in a general manner, but it is usually 1
About 0 minutes to 5 hours is sufficient.

After carrying out the hot alkali treatment in this way, the insoluble solid content is taken out, washed thoroughly with water, and then dried by a method such as freeze-drying to obtain the desired chitosan-chitin-based hollow fiber.

In the hollow fiber thus obtained,
Glucan is substantially not contained, and the content of chitosan and chitin is usually 70% by weight or more. The content ratio of chitosan and chitin depends on the conditions of the hot alkali treatment. By deteriorating this hot alkaline treatment condition, deacetylation of chitin progresses more and the chitosan content increases.

[0015]

EFFECTS OF THE INVENTION According to the method of the present invention, it is possible to suppress the biosynthesis of glucan constituting the cell wall and activate the biosynthesis of chitosan and chitin by controlling the pH during the culture of Rhizopus. As a result, the hollow fibers obtained by the treatment of the cultured cells with hot alkali are substantially free of glucan and have a high content of chitosan and chitin.

The chitosan-chitin-based hollow fiber obtained by the method of the present invention can be easily formed into a sheet, a film, a filter or the like having antibacterial properties and adsorptivity. Since a functional substance such as a physiologically active substance can be added to have various functions, it can be expected to be applied as a new material.

[0017]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example A composition consisting of 45 g of glucose, 7.5 g of polypeptone, 3.0 g of yeast extract, 1.5 g of dipotassium hydrogen phosphate, 0.75 g of magnesium sulfate and 1.5 liter of tap water, in a jar having a capacity of 2 liters. Rhizop, which is a kind of Rhizopus, is added to the medium of
The aus acetoinus) HUT1219 bacterium was aerated and agitated for 3 days under the conditions of a stirring speed of 300 rpm and a culture temperature of 29 ° C. During the culture period, the pH was adjusted to 4.5 or 5. with 1N sodium hydroxide aqueous solution and 1N hydrochloric acid.
Controlled to 8.

Next, 100 ml of a 2 wt% aqueous sodium hydroxide solution was added to 1 g of the dry weight of the cultured cells obtained at each culture pH, and the mixture was placed in an autoclave for 12 hours.
A hot alkali treatment was carried out at 0 ° C. for 1 hour. After the treatment, the insoluble solid matter was taken out, washed well with water, and then freeze-dried to obtain a chitosan-chitin-based hollow fiber.

The chitosan and chitin contents and the glucan contents of these hollow fibers were measured according to the following methods.
The sample was hydrolyzed with 6N hydrochloric acid at 100 ° C. for 9 hours, and then the amount of glucosamine derived from chitosan and chitin was measured by the Tsuji method [“Chemical & Pharmaceutical Bulletin (Chemical & Phasing
rmaceutical Bulletin) "No. 17
Vol., Pp. 1505-1510 (1969)], and the content of anhydrous glucosamine (that is, the content derived from chitosan and chitin) in the hollow fiber is expressed in% by weight.

On the other hand, regarding the glucan content, after hydrolysis with 1N sulfuric acid at 100 ° C. for 8 hours, the amount of glucose derived from glucan was determined by the glucostat method [edited by the Japanese Biochemical Society, “Chemical Chemistry, Lower”]. Page 384 (197)
6 years, published by Tokyo Kagaku Dojin)), and the content of anhydrous glucose (that is, the content of glucan) in the hollow fiber is expressed in% by weight. The results are shown in Table 1.

Comparative Example The same procedure as in Example was carried out except that the pH was not controlled during the culture of Rhizopus. Table 1 shows the results. The pH during culturing varied within the range of 3.3 to 6.5.

[0023]

[Table 1]

From Table 1, it can be seen that the hollow fibers obtained by controlling the culture pH to 4.5 or 5.8 contain almost no glucan and the chitosan and chitin contents are improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masafumi Nishiyama 2-3-3 Hananomiyacho, Takamatsu City, Kagawa Prefectural Institute of Industrial Technology Shikoku Institute of Industrial Technology

Claims (3)

[Claims] 1. A method for producing a chitosan-chitin-based hollow fiber substantially free of glucan, which comprises subjecting Rhizopus cells cultured under conditions of pH 4.0 to 6.0 to hot alkali treatment. 2. The method according to claim 1, wherein the hot alkali treatment is carried out at a temperature of 80 to 150 ° C. using a 0.5 to 5 wt% sodium hydroxide aqueous solution. 3. The Rhizopus acetoinus HUT121 is a Rhizopus bacterium.
The method according to claim 1 or 2, which is 9 bacteria.