JPH07163334A - Activity maintenance and storage of fluorescent bacterium and microorganism material comprising its culture product - Google Patents

Abstract

PURPOSE:To maintain the activities of fluorescent bacteria living in the roots of a plant, and to perform the growth stimulation, yield increase and disease control of agricultural crops with the activated microorganisms or their culture product, thus improving the productivity of agriculture. CONSTITUTION:Fluorescent bacteria separated from the roots of a plant are subjected to a symbiotic culture together with the culture roots of the same kind of a plant as that of the separating source to maintain the activities of the fluorescent bacteria, and the culture product obtained by culturing the fluorescent bacteria is used as a microorganism material. The fluorescent bacteria subjected to the symbiotic culture can be immobilized and dried for storage in a state maintaining the activities of the fluorescent bacteria. The fluorescent bacteria can massively cultured by culturing the immobilized fluorescent bacteria. The application of the culture product of such fluorescent bacteria to plants such as agricultural crops as a microorganism material exerts remarkable effects on the control of soil diseases the growth stimulation of the plants.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for maintaining and preserving the activity of a fluorescent bacterium inhabiting the rhizosphere, particularly a plant root, and a microbial material consisting of this culture. The purpose of the culture is to promote the growth of agricultural crops, increase the yield, and control diseases, thereby improving agricultural productivity.

[0002]

2. Description of the Related Art In recent years, many studies and reports have been made on the utilization of useful microorganisms in the agricultural field. These are mainly related to biological control of soil diseases, and the antagonistic action of useful microorganisms against pathogens is considered to be a particularly important function. In addition, with regard to various antibiotics produced by such useful microorganisms, many studies have been conducted on the action mechanism as an antagonist. Among them, Pseudomonas bacteria are known to have high ability to produce such antagonists and to easily settle on the root surface of plants. Therefore, studies have been carried out to promote the growth of plants by inoculating the plants with this bacterium and thereby increase the yield of the plant.
h Promoting Rhizobacteria: Plant growth promoting rhizobacteria)
Has been called. But such a PG
Regarding the action by PR, only a theoretical explanation of the mechanism of action via the siderophore, which is a substance produced by this bacterium, and empirical elucidation of the biological control action of soil diseases and the growth promotion action of plants by the bacterium Of course, the reality is that practical effects have not yet been realized.

[0003]

There are many problems in using the above-mentioned bacteria such as PGPR for controlling soil diseases of plants such as agricultural crops and promoting the growth of plants. That is, there is a problem in handling useful microorganisms retrieved from natural ecosystems. The question is how to maintain the useful functions of microorganisms in natural ecosystems without inactivating them. Furthermore, there is a problem of how to store such microorganisms for practical use and to transfer them to mass culture. Next, there is a problem when the cultured microorganisms are applied to the soil again. That is, even if it is a microorganism isolated from a plant or rhizosphere soil, artificial separation and culturing are applied to the natural soil again,
Stable establishment of this in soil or in plants is currently considered extremely difficult technology. That is, the microorganisms applied to the soil become more inferior by competition with many indigenous bacteria already existing in the soil, and it becomes difficult to stably establish in the rhizosphere environment of the plant.

Therefore, in order to utilize microorganisms such as PGPR for controlling soil diseases and promoting growth of plants, it is necessary to solve such problems. Specifically, a Pseudomonas bacterium with a high affinity for plant roots was searched from the rhizosphere soil or the root surface of the plant, and a method of fixing the Pseudomonas bacteria to the plant by seed bacteriosis or the like was isolated from the plant. A method of inoculating a plant again with a microorganism to grow and settle in the plant is being studied. For example,
A method of separating and selecting a symbiotic microorganism useful for disease control by trapping the microorganism in the hypocotyl, or separating and culturing a symbiotic microorganism in an asymptomatic tissue, and selecting this microorganism as a bacterium having an affinity for these microorganisms. For example, the method of inoculation.
However, all of these remain in the research stage and have not yet solved such problems. In order to solve such problems, the present inventors have paid particular attention to a method of utilizing a microorganism that focuses on a crop root at the time of cultivating a plant body, inhabits in the plant root, and is colonized. As a result of the repetition, the present invention has been reached.

[0005]

[Means for Solving the Problems] That is, the present invention is characterized in that a fluorescent bacterium isolated from the inside of a plant root is co-cultivated with a culture root of a plant of the same species as the plant of the source of separation. The present invention relates to a method for maintaining bacterial activity and a microbial material comprising a culture obtained by such co-cultivation. Further, the present invention is a method for preserving fluorescent bacteria, characterized in that a culture root is collected from such a culture, and the cells are fixed cells, and then dried, and a culture in which such a preservation bacterium is cultured. It relates to a microbial material consisting of things. The present invention utilizes a fluorescent bacterium that is inhabited and settled in a plant root,
It is characterized by separating such fluorescent bacteria and reproducing the state inhabiting the plant roots by co-culturing them and selecting active bacteria and using them without reducing this activity. I have.

[0006]

The method for maintaining and preserving the activity of the fluorescent bacterium of the present invention and the microbial material comprising this culture will be described in more detail below. The fluorescent bacterium of the present invention is a bacterium isolated from within a plant, particularly within a plant root. Examples of such fluorescent bacteria include various biotypes of Pseudomonas fluorescens and root-root-fixing fluorescent bacteria such as Pseudomonas putida. The means for separating such root-root-fixing fluorescent bacteria may be a method of sterilizing the surface of the plant root and then separating the bacteria.
However, in separating and culturing the bacteria, it is desirable to culture them under oligotrophic conditions as nutrient conditions during the culture in order to maintain the activity of the bacteria. For example, a method may be used in which the surface of the plant root is washed and sterilized with ethanol or the like, and then the plant root is homogenized and then directly pour-cultured with bare agar. Separation culture is performed by such a method, and then colonies that emit fluorescence are selected from the generated colonies. The colonies composed of the separated fluorescent bacteria are then subjected to the activity maintaining method of the present invention.

The activity maintaining method of the present invention is established in roots,
And, in order to grow the fluorescent bacteria that were in a symbiotic state with the plant roots in an environment similar to that before separation, it is characterized by being co-cultivated with the culture roots of the plant of the same species as the plant of the separation source. Yes, the method is as follows.

First, seeds of a plant of the same species as the plant in which the above-mentioned fluorescent bacteria have been separated in advance are used, sterilized and then germinated and grown on agar agar medium or the like. In this case, the seeds used for germination and growth are especially important.
The purpose is to use seeds of a plant of the same species as the plant from which the fluorescent bacteria have been separated, and in this case, the use of seeds of different plants cannot achieve the object of the present invention. In addition, the same type of plant body in this case refers to types such as tomato, eggplant, and cucumber, and may be any variety as long as it is the same plant body type. Furthermore, in the present invention, only the root tips grown by germination of seeds are used, but the use of a portion other than the root tips of the plant body grown in this case cannot achieve the object of the present invention. Further, in the present invention, in addition to the germinated and grown plant root tip, even if an adventitious root obtained by culturing undifferentiated plant cells such as callus or hairy root is used, the same object of the present invention can be achieved. I can't. In the present invention,
The root tips of the germinated and grown seedlings are separated, and the root tips are cultured in a medium such as white medium. The root tip culture root thus obtained is subjected to the subsequent co-cultivation.

The co-cultivation method uses white medium or the like,
The root tip culture roots are transferred to this, and the colonies consisting of the above-mentioned separated fluorescent bacteria are inoculated and cultured for about 10 days. In this case, the fluorescent bacterium grows in the root or the root surface of the plant in the culture solution, but by growing the fluorescent bacterium in the root or the root surface in this way, the decrease in the activity of the bacterium is extremely suppressed, When this bacterium is used as a microbial material, the activity of fluorescent bacteria in plant roots can be maintained.
Fluorescent bacteria whose activity has been maintained in this way can be used as the microbial material described below as it is as a culture, but more desirably, the bacteria screened by performing a further functional assay for the bacteria in the culture solution. By further performing the co-cultivation as described above, the effect of the fluorescent bacteria becomes more certain.

Next, the microbial material of the present invention will be described in detail. In the present invention, the culture product thus co-cultivated may be used as it is, or a culture root and a culture solution containing fluorescent bacteria may be used. It is also possible to separate and to use each individually. As a utilization form of the microbial material, there is a bacterification method for plug seedlings, seeds, and soil of a culture. More specifically, a method in which the culture solution or its isolated culture root is used by coating it on sterilized seeds, or a method in which the culture solution is directly mixed with sowing soil, bed soil, etc., and further, a culture root is suitable. There is a method of immobilizing using a different carrier and using it as an immobilized microorganism. In such a case, it is desirable that the bacterial concentration in the culture medium when the culture medium is used as it is is approximately 10 ⁵ cells / ml or more.

Next, a more preferable mode of the present invention will be described in detail. The present invention, as described above, the fluorescent bacteria isolated from the inside of the plant root, the main feature in co-cultivating with the culture root of the plant of the same species as the plant of the source of separation, but by such culture The obtained fluorescent bacteria are difficult to store for a long period of time while maintaining this activity. That is, when the culture after co-cultivation is stored as it is, it is limited to 1 to 2 months. In addition, when the bacteria after co-cultivation are separated and stored by a known preservation method, the activity of fluorescent bacteria is remarkably reduced, and the morphological and physiological characteristics of the bacteria during co-cultivation due to mutation of the bacteria. Can't be maintained. Therefore, a further object of the present invention is to preserve the activity of the fluorescent bacterium after co-cultivation described above without lowering the activity, and to utilize the fluorescent bacterium after co-cultivation more effectively as a microbial material. It is to mass-culture this fluorescent bacterium.

The method for preserving the fluorescent bacteria of the present invention will be described in detail. First, only the culture roots in the culture obtained by the above co-cultivation are separated by a means such as filtration. Then
This cultured root is used as an immobilized cell, and this method can be performed by a commonly used cell immobilization technique.
For example, first, the culture root is homogenized, and then a sodium alginate solution is added thereto and stirred. This culture root dispersion is added dropwise to a liquid such as calcium chloride to give fixed cells of plant somatic cells containing fluorescent bacteria having a diameter of about 3 to 6 mm.
Such fixed cells can be stored for a long period of time without decreasing the activity of fluorescent bacteria by using a desiccant such as silica gel or phosphorus pentoxide and drying them at 40 ° C or lower for a short time. It will be possible.

Further, in the above-mentioned fixed cells or dry fixed cells, the immobilized fluorescent bacteria grow by culturing the cells, and the bacterial concentration in the culture solution after co-cultivation as described above is generally From 10 ⁵ to 10 ⁶ cells / ml, this fixed cell culture increases the bacterial concentration to about 10 ⁹ to 10 ¹⁰ cells / ml. The culture method is, for example, about 2 weeks of culture in a potato-dextrose medium or the like. At the beginning of the culture, the bacteria in the immobilized cells form colonies around the plant cells, and fluorescent bacteria that have an affinity for the plant cells grow, and from the middle to the second half of the culture, the nutrient source is supplied from outside the cell. At the same time, the bacteria pass through the surface of the immobilized cells and grow while transferring into the culture medium.

By using the culture in which the fluorescent bacteria are proliferated as described above and using this as the above-mentioned microbial material, the microbial material of the present invention becomes more practical. The means for applying such a fixed cell to a microbial material is as described above.

[0015]

The present invention will be further described below with reference to examples of the present invention, but the present invention is not limited thereto. In this example,% means% by weight unless otherwise specified.

(Example 1) 1. Separation and culture of fluorescent bacteria Centering on in-house-grown crops in Hyogo prefecture, crops under cultivation from the seedling stage to the end of harvest are collected and Isolation of fluorescent bacteria was performed. The method of separation was to wash the roots of the collected crops, sterilize the roots with ethanol, homogenize the roots, and pour the homogenized mixture into pure agar. Then, colonies that emit fluorescence were selected from the colonies formed in the culture. Table 1 shows the strains isolated from tomatoes (variety: Mizuken, Mizuei, House Momotaro), bok choy, and leek roots in facility-grown fields in Nishi-ku, Kobe-shi and Himeji-shi, Aboshi-ku, Hyogo Prefecture. In addition, these bacterial strains were evaluated for antibacterial activity against various pathogenic bacteria, and the results are also shown in Table 1. The bacteriological characteristics of the representative strains in Table 1 are shown in Table 2. Furthermore, the strains used in the examples of the present invention, after isolation of the bacteria, using a 5-fold diluted potato dextrose agar slant medium, after subculture at 23-25 ° C. for 5-7 days, 4-6 The one stored at ℃ was used.

2. Root tip culture In order to subject the above-mentioned preserved strains to co-cultivation, seeds of the same species as the plant of the separation source were used to obtain culture roots. First, the seeds of each of the varieties of tomatoes, Zuiken, Ruiei, Hausomoro, and First Memory are used, and the seeds are surface sterilized with a 1% sodium hypochlorite aqueous solution and an 80% ethanol aqueous solution. Was sown on 0.8% bare agar and kept at 23 ° C. under dark aerobic condition for 5 days to germinate seeds. Approximately 1 cm of the germinated seed root was cut off and inoculated into a white liquid medium. This medium was kept at 25 ° C for about 10 days to culture root tips, and then the grown cultured roots were subcultured to a new white liquid medium, and further cultured at 25 ° C for about 10 days.

3. Co-cultivation method In the co-cultivation method, first, the above-mentioned culture roots were added to a 10-fold diluted white liquid medium and cultured at 25 ° C. for 1 to 2 days. Then, inoculate this with the subculture of the above 1.
Weekly co-cultivation was performed. After completion of the culture, the culture root was taken out and washed with sterilized water. In order to evaluate the activity of the cultivated bacteria co-cultivated in this manner, several roots of about 1 cm long were collected from the site excluding the root end of the cultured roots, which were the same as the subcultured bacteria before the culturing. To obtain the culture conditions, 5 culture roots
Inoculate the double-diluted potato dextrose agar slant medium,
Culture was performed at 23 to 25 ° C for 5 to 7 days. Then, it was investigated whether or not the test strains after symbiotic culture could coexist. The results are shown in Table 3. The comparison of the activity between the subculture bacteria and the co-cultivation bacteria is made by the following root root fixing capacity evaluation test, antibacterial substance production capacity evaluation test against pathogenic bacteria, plant growth promoting capacity evaluation test, disease control activity evaluation test. did.

A. Intra-root colonization ability evaluation test The medium components adhering to the culture root in the above 2. were washed off with sterilized water. Cutting the cultured roots about 1cm intervals, it was immersed for 24 hours in test bacteria liquid prepared in 10 ⁵ cells / ml concentration with sterilized water. After soaking, the roots were washed with sterile water and kept in a test tube containing sterile water at 25 ° C for 2 days. Then
The root was taken out from the test tube, washed with sterilized water, the center part of the root was cut, and the cut surface was replicated on a slide glass. After air-drying the replicated glass, flame fixation was performed, and the inoculum growth state in the roots was observed by Gram staining. The evaluation test results are shown in Table 4.

B. Evaluation of antibacterial substance production ability against pathogenic bacteria
As test pathogens, tomato wilt disease fungus, tomato wilt disease fungus, tomato root rot wilt disease fungus and the like were used, and the ability of each test strain to produce an antibacterial substance against the pathogenic fungus was evaluated. The evaluation test was carried out by the plate chloroform method and the pour-in culture method for the bacterial wilt disease of tomato, and by the confrontation culture method for other pathogenic filamentous fungi. Table 5 shows the evaluation test results by the plate chloroform method for the subcultured bacteria and co-cultivated bacteria of the test bacterium No. F-16. Also, test bacteria No. T-32 and T
-33 subculture and co-cultivation were used to evaluate the antibacterial substance-producing ability by the pour-in culture method for bacterial wilt disease and the confrontation culture method for other pathogens. . The results are shown in Table 6.

C. Plant Growth Promoting Ability Evaluation Test Using the tomato seeds of each variety used in the root tip culture described above, after germination of the seeds, the seeds were allowed to grow on an agar medium for 1 week under light and aerobic conditions. It was The roots of the grown seedlings were cut, and the saplings were cut into white agar medium (without sucrose added). The cuttings were grown for 24 hours under aerobic conditions at 28 to 30 ° C, and a test bacterial solution prepared to have a concentration of 10 ⁵ cells / ml with sterile water was added to the medium at a volume of about 1 v / v%. The cuttings were inoculated so that Cultivation was continued even after inoculation with the fungus, and an evaluation test was performed for rooting action of the cuttings. As an evaluation test result, the rooting action of various test bacteria on tomato house Momotaro is shown in Table 7, and the rooting action of various test bacteria No. F-16 on various tomato varieties is shown in Table 8.

D. Disease Control Activity Evaluation Test Tomato seeds of each variety used in the above-mentioned root tip culture were used, and this seed was germinated. Immediately after germination of the seed, this was placed on a medium in which a white agar medium (without sucrose added) was previously formed in the lower layer, a sea sand layer of 3 to 5 mm was formed in the middle layer, and an agar medium was formed in the upper layer, and 28 to 30 ° C. Were grown under light and aerobic conditions. When the tip of the germinated root reaches the sea sand layer from the agar layer, the test bacterial solution prepared to a concentration of 10 ⁵ cells / ml with sterilized water is added to the surface of the medium so that it is about 1 v / v% of the medium volume. Was inoculated. After continuing the growth of germinated seeds for 24 hours after inoculation of the fungus, add bacterial wilt disease solution prepared to a concentration of 10 ⁷ cells / ml with sterile water to the surface of the medium so that the volume is about 2 v / v% of the medium volume. Was inoculated. After the inoculation of this pathogen, we continue to grow under the same conditions and carry out morbidity surveys.
An evaluation test was performed for disease control activity. The evaluation test results are shown in Table 9.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

[0028]

[Table 6]

[0029]

[Table 7]

[0030]

[Table 8]

[0031]

[Table 9]

(Example 2) No. F-16 of Table 3 in which co-cultivation was carried out using isolated roots of tomato (variety: House Momotaro)
The culture (300 ml) was separated into symbiotic roots and a culture solution by filtration. Put the separated symbiotic root in 300 ml of 1% sodium alginate aqueous solution, and use a homogenizer to rotate at 8,000-1000 rpm.
The mixture was subjected to mixed pulverization for about 10 minutes under the condition of 0 rpm to obtain a gel material No. 1 microbial material.

In addition, tomatoes (cultivar: First Memory) are used for co-cultivation.
The culture (300 ml) of No. T-32 in Table 3, which was cultivated using the isolated root of No. 3, was separated by filtration into a symbiotic root and a culture solution. Add 300 ml of 2% sodium alginate aqueous solution to the separated culture solution,
While stirring, 240 g of silica powder was added to this to obtain a powdery material No. 2 of the microbial material. The separated symbiotic roots are 3 g in 300 ml of 1% sodium alginate aqueous solution.
The activated carbon was added to the solution, and the mixture was subjected to mixed pulverization for about 10 minutes under the condition of a rotation speed of 8,000 to 10,000 rpm using a homogenizer to obtain a gel-like microbial material. Next, 40 g of silica powder was added to 100 ml of this gel-like microbial material to obtain powdery microbial material of Material No. 3.

Using the prepared microbial materials Nos. 1 to 3, seeds were subjected to bacterification treatment and soil treatment. First, the seed bacteriolysis
Tomato (variety: large Fukuju, House Momotaro) seeds are used, and after the seeds are sterilized, they are immersed in the microbial material of Material No. 1, then in a 1% calcium chloride aqueous solution, and immediately sterilized water. The seed surface was washed with and stored at 4-6 ° C. Further, a part of the seeds treated with the microbial material of Material No. 1 was further coated with the microbial material of Material No. 3 to obtain seeds treated with bacteria of two types of fluorescent bacteria.

The soil used as the treated soil is a contaminated soil having a bacterial density of tomato wilt disease of 10 ⁵ to 10 ⁶ (cfu / g dry soil). To this soil, mix the microbial material of material No. 2 to about 10 v / v%, and mix the microbial material of material No. 3 to about 5 v / v%, and mix them for seeding. It was treated soil.

A tomato cultivation test was carried out using various microbial materials, bacterification-treated seeds and treated soil. In addition, the bacterial density of tomato wilt fungus 10 ⁵ to 10 ⁶ (cfu / g dry soil)
The soil was designated as contaminated soil. The test method was as follows. First, a tray for plug seedlings having a capacity of about 15 ml per hole was filled with contaminated soil and treated soil, and this tray was embedded in the soil surface on which the contaminated soil was laid. Then, tomato seeds were sown on this, but the bacterium seeds were sown on the tray filled with the contaminated soil, and the untreated seeds (tomato varieties: large Fukuju, House Momotaro) were sown on the tray filled with the treated soil. . After sowing the seeds, tomatoes were cultivated in the house while the cultivation was controlled by automatic irrigation, etc., and the disease state was investigated by observing the growth condition of the seedlings. The results are shown in Table 10.

[0037]

[Table 10]

(Example 3) In the same manner as in Example 1, using 5 strains and 5 kinds of test roots isolated from tomatoes grown in-house, co-cultivation was carried out in the same manner as in Example 1 to obtain symbiotic roots. . This symbiotic root was homogenized in a 1% sodium alginate aqueous solution containing 1% activated carbon to form a gel solution, and this gel solution was dropped into a 1% calcium chloride aqueous solution to fix the outer diameter of about 5 mm. The activated cells were obtained. Next, a filter paper was placed in a closed container filled with silica gel, the immobilized cells were spread on the filter paper, and this was maintained at 30 ° C. for 1 hour to dry the immobilized cells. The dried fixed cells were vacuum-sealed in ampoules and refrigerated for 2 months.

In order to evaluate the activity of the dried and fixed cells stored, the fixed cells were placed on a 5-fold diluted potato-dextrose agar plate and cultured at 25 to 28 ° C. for 5 days. In the same manner as in Example 1, this culture was subjected to the root root colonization ability evaluation test and the antibacterial substance production ability evaluation test against pathogenic bacteria. Restorability of the preserved bacteria is shown in Table 11, and fixing ability and antibacterial activity are shown in Tables 12 and 13.

[0040]

[Table 11]

[0041]

[Table 12]

[0042]

[Table 13]

(Example 4) Isolation of Example 1 Using the fluorescent bacteria Table 1 strain No. T-33, a symbiotic root obtained by symbiotic culture with an isolated root of tomato (variety: House Momotaro) was isolated. did.
This symbiotic root was homogenized in a 1% sodium alginate aqueous solution to give a gel solution, and the gel solution was
Immobilized cells with an outer diameter of about 5 mm were obtained by dropping into an aqueous solution of calcium chloride. Then one of the fixed cells
After taking 0 grain, inoculating this with 200 ml of a 5-fold diluted potato dextrose solution, static culture was performed at 30 ° C. for 10 days. After culturing for 10 days, the culture excluding the fixed cells was extracted. The extracted culture was inoculated on a 5-fold diluted potato-dextrose agar slant medium and cultured at 23 to 25 ° C for 5 to 7 days. With respect to the strains after the culture, as in Example 1, the root-root colonization ability evaluation test and the antibacterial substance production ability evaluation test against pathogenic bacteria were performed. The evaluation test results are shown in Tables 14 and 15.

Using the extracted culture, a microbial material was prepared by the same method as the method for preparing the microbial material of Material No. 2 of Example 2. Using this material, in order to test the growth promoting action of seedlings in the tomato seedling raising period by applying the material and to test the resistance to bacterial wilt disease after planting in pathogen-contaminated soil, A cultivation test was conducted.

As for the cultivation test method, first, the volume of one hole is about 15 ml.
The plug seedling tray was filled with a soil containing the above-mentioned microbial materials mixed at 5 v / v% with respect to the commercially available horticultural soil, and the seeds of tomato (variety: House Momotaro) were sown in this 14
Raised for a day. Next, a potting medium was prepared in the same manner as above, and the above-grown tomato seedlings were transplanted into pots filled with this prepared medium, and then cultivation was continued for 16 days. After 16 days of cultivation, the seedlings were examined for growth and the results are shown in Table 16. After the growth survey, the seedlings were planted in a field (pathogen density: 10 ⁵ to 10 ⁷ cfu / g dry soil) contaminated with tomato wilt fungus, and the disease control effect was tested by investigating the number of diseased seedlings. The results are shown in Table 17.

[0046]

[Table 14]

[0047]

[Table 15]

[0048]

[Table 16]

[0049]

[Table 17]

[0050]

INDUSTRIAL APPLICABILITY The method for maintaining the activity of a fluorescent bacterium of the present invention is utilized without reducing the activity of the fluorescent bacterium by reproducing the state inhabiting the plant root when the fluorescent bacterium is separated and cultured. be able to. Further, the culture containing the fluorescent bacteria obtained by such a method and cultivated, by applying this to plants such as agricultural crops, a remarkable effect is exhibited in controlling soil diseases and promoting the growth of plants. It becomes an excellent microbial material.

Further, in order to make the effect of the present invention more effective, the plant cells containing the symbiotic microorganisms in the above culture are fractionated, made into fixed cells, and then dried in a short time. As a result, fluorescent bacteria can be stored for a long period of time without lowering their activity, and by culturing such fixed cells, large-scale cultivation of fluorescent bacteria becomes possible. Therefore, by using such a culture as a microbial material, the effect of the present invention becomes more practical.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiko Shimizu 3 at 161 Nishishitshiro, Shimohata-cho, Tarumi-ku, Kobe-shi, Hyogo (72) Inventor Akihiro Ushio 4 at 1220 Asazuma-cho, Kasai-shi, Hyogo (72) Invention Takeo Kuwana 4 1220 Asazuma-cho, Kasai-shi, Hyogo Prefecture (72) Inventor Kobayashi 3-7-606 Asahi-cho, Takarazuka-shi Hyogo (72) Inventor Shoji Kobayashi 2-chome Yamate, Kakogawa-shi Hyogo (72) Minoru Matsuyama 1338 Okubo, Okubo-cho, Akashi-shi, Hyogo Prefecture (72) Yoshio Maekawa 3-491 Higashi Jiyugaoka, Shizome-cho, Miki-shi, Hyogo (72) Taizo Akiyama Kamizume 331, Yoneda-cho, Takasago-shi, Hyogo Address-9 (72) Inventor Yoshinori Hayashi 2689-1 Oka, Inami-cho, Kako-gun, Hyogo Prefecture

Claims (4)

[Claims] 1. A fluorescent bacterium isolated from the root of a plant,
A method for maintaining the activity of a fluorescent bacterium, which comprises co-culturing with a culture root of a plant of the same species as a plant of a separation source. 2. A fluorescent bacterium isolated from the inside of a plant root,
A microbial material comprising a culture that is co-cultivated with a culture root of a plant of the same species as the plant of the separation source. 3. A fluorescent bacterium isolated from the inside of a plant root,
Co-cultivated with a culture root of a plant of the same species as the plant of the separation source,
Next, a method for preserving fluorescent bacteria, which comprises collecting the cultured roots, making them fixed cells, and then drying. 4. A fluorescent bacterium isolated from the root of a plant,
Co-cultivated with a culture root of a plant of the same species as the plant of the separation source,
Then, the cultivated root is separated, and the cultivated material is used as a fixed cell, and the cultivated material is further cultivated.