JPH06327463A - Lignin decomposing fungus and usage thereof - Google Patents

Abstract

PURPOSE:To provide a new kind of microbe applicable to such industrial uses as to decompose or oligomerize lignin typified by pulp bleaching, and to provide usage thereof. CONSTITUTION:There are provided a microbe SKB-207 strain excellent in lignin decomposing activity and pulp bleaching performance; a method for bleaching pulp using the microbes; a method for decoloring pulp waste liquor: and a method for producing pulp through such bleaching or decoloring process using the microbes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lignin-degrading bacterium and a method of using the same, and more particularly to a microorganism excellent in lignin decomposing ability and pulp bleaching performance and a method of using the same.

[0002]

2. Description of the Related Art Conventionally, many attempts have been made to decompose lignin by microorganisms and utilize it in the pulp and paper industry. For these purposes, white rot, which is a bacterium that selectively decomposes lignin, has been used. A series of basidiomycetes called fungi are used. Among these, especially Kawaratake (Co
riolus versicolor) and Phanerocheate chrysporium have attracted attention as representative bacteria and have been used for research.

On the other hand, conventionally, chlorine-based chemicals such as chlorine and chlorine dioxide have been widely used for bleaching pulp. However, in recent years, it has become clear that these chlorine-based chemicals produce dioxin, which is known as a highly toxic substance, and the use thereof is being restricted. Therefore, development of various bleaching agents instead of chlorine-based chemicals has been attempted, but biobleaching of bleaching pulp using the lignin-degrading bacterium is one of these effective methods. Is being energetically studied in.

[0004]

However, the above-mentioned strains have insufficient lignin degrading activity and lack the selectivity of degrading only lignin, so that they decompose lignin and simultaneously produce polysaccharides such as cellulose and hemicellulose. It also had the drawback of breaking down. Therefore, in the conventional biobleaching, the pulp viscosity and the pulp yield are lowered, so that it cannot be industrially utilized.

Therefore, the present inventors have developed a method for selecting a lignin-degrading bacterium, which is capable of highly accurately determining and separating a lignin-degrading bacterium from a group of microorganisms mainly present in decayed wood. That is, this method is inoculated with a microbial group in a medium containing a pulp having lignin and cultured,
It is a method for selecting a lignin-degrading bacterium that determines that the one that decolorizes the medium is a lignin-degrading bacterium.

[0006] The present inventors have conducted extensive studies based on the above-described selection method of lignin-degrading bacteria to isolate a novel microorganism having a high pulp bleaching activity, and as a result, succeeded in separating a pulp bleaching microorganism having a high lignin-degrading activity. Has reached the present invention. Therefore, a first object of the present invention is to provide a pulp bleaching microorganism having excellent lignin decomposing activity and pulp bleaching performance. A second object of the present invention is to provide a safe and highly efficient pulp bleaching method using a pulp bleaching microorganism having the above properties.

[0007]

The above objects of the present invention are to achieve the microorganism SKB- which is excellent in pulp bleaching ability and lignin decomposing ability.
207 strain and pulp bleaching method using the same. The novel microorganism SKB-207 strain of the present invention has the mycological properties shown in Table 1.

(1) Growth condition in culture medium

[Table 1]

(2) Physiological and ecological properties Range of growth pH range of growth (potato decoction / dextrose medium, 3
Culturing at 0 ° C. for 3 days) is in the range of 3 to 9 and does not grow at pH 2 or lower and 10 or higher. The optimum pH range is 4 to
8

Growth temperature range The growth temperature is in the range of 24 to 37 ° C., and it does not grow particularly at 45 ° C. or higher (potato decoction / dextrose agar medium, pH 5.6, 4 days culture). Phenol oxidase reaction Weak or negative (culture at 30 ° C for 3 days). Characteristics of bacterial flora White and thin felt-like (potato decoction / dextrose agar medium, pH 5.6, cultivated for 4 days).

[0011] These physiological and ecological properties and the mycological properties such as the growth state in each medium were examined in detail, but they could not be identified as known bacteria. However, as is clear from the examples described below, this bacterium is superior in lignin degrading activity and bleaching activity to the conventionally known representative lignin-degrading bacteria, such as Kawaratake and Fanelocete.

Since such a bacterium having both excellent activities does not exist in the conventionally known microorganisms, this strain was identified as a new strain, named SKB-207 strain, and deposited at the Institute for Microbial Research, Institute of Industrial Science and Technology. (Deposit number: FERM P133
53). Since there are still some uncertainties regarding the exact taxonomic location of this strain, accurate identification is difficult at this point, and we must wait for future research.

Next, the novel microorganism SKB- according to the present invention
The pulp bleaching method using the 207 strain will be described.
Basically, the bleaching of the pulp with this strain may be carried out by inoculating the pulp with the bacterium and culturing for a predetermined period of time, and the conditions thereof are not particularly limited. That is, the pulp concentration, temperature, pH and the like can be appropriately selected within the range where the bacterium has activity. For example, regarding pulp concentration, good results can usually be obtained within the range of 20 to 60%.

The temperature, pH, etc. may be within the range described in the above-mentioned physiological properties, and a nutrient source may be further added to improve the growth of the bacterium. As described above, when the present strain is used for bleaching pulp, the pulp may be inoculated with the present strain and cultured for a predetermined time as in the conventional method. When used in various wood utilization industries, this strain may be inoculated and cultured for a predetermined time, and one of the excellent features of the present invention is that no special consideration is required.

Further, since this bacterium has an excellent lignin decomposing power, it can be used for bleaching pulp as well as for decolorizing pulp waste liquid under the same conditions as the above bleaching conditions. Furthermore, the industrial production method of various pulps can be improved by utilizing the ability of this bacterium to decompose lignin and reduce its molecular weight.

[0016]

EFFECTS OF THE INVENTION The pulp bleaching microorganism of the present invention has a significantly better lignin decomposing activity and pulp bleaching performance than existing bacteria. Therefore, the pulp bleaching and other lignin degrading processes in the paper manufacturing process are decomposed. Alternatively, it can be used for industrial purposes such as lowering the molecular weight, for example, a pulp manufacturing process, a decolorizing process of pulp wastewater, a wood saccharification process, and the like.

[0017]

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

Example 1 SKB-207 strain was cultivated in a potato dextrose medium (DIFCO) containing 0.4% of potato decoction and 2% of glucose, and allowed to stand for 1 week. Next, after crushing the produced bacterial mat with a Waring blender,
Commercially available oxygen bleached pulp heat-sterilized at 0 ° C for 15 minutes,
The bacterial cell suspension was added so that the pulp concentration finally became 20%, and the mixture was allowed to stand at a temperature of 30 ° C. for 7 days.

Next, 500 ml of water was added and defibrated with a mixer to prepare a hand-made sheet, and the whiteness of the sheet was measured using a Hunter whiteness meter (JIS P8123), and at the same time, the Kappa number was measured (JIS. P822-1
976). For comparison, representative lignin-degrading bacteria such as Coriolus versicolor and Phanerocheate chrysp
The same operation was performed for orium). The results are shown in Table 2.

[0020]

[Table 2] As is clear from Table 2, the novel microorganisms according to the present invention have the bleaching activity far superior to that of the conventional microorganisms,
It was found that a large improvement in whiteness and a reduction in Kappa number could be realized.

Example 2 The three strains used in Example 1 were cultivated in potato decoction dextrose agar medium, and each disc was punched out with a cork borer. The cells were inoculated into a medium prepared by adding 4.0 ml of water to 0.0 g and cultured at 30 ° C. for 2 weeks. After culturing,
Klarson lignin in wood flour (JIS P-1961)
And acid-soluble lignin (edited by Junzo Nakano, Chemistry of Lignin (Uni Publishing) P53) were quantified. The results are shown in Table 3.

[0022]

[Table 3] As is clear from the results shown in Table 3 above, the novel microorganism according to the present invention is far superior in lignin activity to conventional bacteria.

Example 3 The three strains used in Example 2 were cultivated in potato decoction dextrose agar medium, and each microbial cell was inoculated into high pressure sterilized poplar chips and statically cultured at 25 ° C. for 1 month. . After that, the hyphae on the chips are removed and washed with water, and the primary defibration pulp is defibrated under the conditions of steam 1.3 kg / cm ² and clearance 0.34 mm. To the 4th order, and the defibration energy is calculated from the energy difference required at the time of defibration and load using an integrated wattmeter, and the paper quality characteristics of the adjusted pulp are determined by the Canadian standard freeness and JIS method. (P-8113, 8116). The results are shown in Tables 4 and 5.

[0024]

[Table 4]

[0025]

[Table 5]

Example 4 The three strains used in Example 1 were cultivated in potato decoction dextrose agar, and the infested hyphae were punched out together with the medium with a cork borer, and three discs thereof were sterilized in advance with hardwood kraft pulp bleached. It was put into the waste liquid of the alkaline extraction stage (E1) of the process and then filtered through a 0.45 μm membrane filter to remove the cells, and then 4
The absorbance at 65 nm was measured, and the reduction rate was measured from the difference with the absorbance of the original waste liquid. The results are shown in Table 6.

[0027]

[Table 6]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location D21H 11/00 (72) Inventor Kunimitsu Murakami 2-8-1, Iida-cho, Iwakuni-shi, Yamaguchi Japan Biological Science Laboratory, Paper Manufacturing Co., Ltd.

Claims (4)

[Claims] 1. A microorganism SKB-207 strain having excellent lignin degrading activity and pulp bleaching activity. 2. A method for bleaching pulp, which comprises culturing after inoculating pulp with a microorganism SKB-207 strain having excellent lignin degrading activity and pulp bleaching activity. 3. A method for producing pulp, which comprises inoculating chips with a microorganism SKB-207 strain excellent in lignin-degrading activity and pulp bleaching activity and then culturing. 4. A method for decolorizing a pulp waste liquid, which comprises inoculating a pulp waste liquid with a microorganism SKB-207 strain having an excellent lignin degrading activity and a pulp bleaching activity and then culturing.