JPH0558832A - Soil conditioning by using microorganism - Google Patents

Abstract

PURPOSE:To improve the effect on preventing soil diseases by utilizing a new microorganism having an expelling effect (productivity of antibiotic) on harmful microorganisms in the soil, capable of behaving as a dominate strain among microorganismic flora in the soil and showing a high safety, and carrying out soil conditioning. CONSTITUTION:Soil conditioning is carried out by inoculating (including application method such as mixing besides seeding, addition, spraying and injection) a new cultured strain of Bacillus natto TT8-2 (Bikoken stipulation No.12338) showing a fungicidal effect, preferably the strain cultured in a soybean soup as a waste in production of fermented soybean of fermented soybean paste or with an insoluble residue in production of soybean curd, fried soybean curd, etc., and growing it onto the soil. This method can not only effectively prevent soil diseases, especially ones caused by fungi but is remarkably excellent in view of safety since the microorganism utilized for soil conditioning is Bacillus natto having been used for food from old times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel soil improvement method using microorganisms.

[0002]

2. Description of the Related Art In recent years, in the cultivation of vegetables and fruit trees, it is unavoidable to carry out continuous cropping in order to meet a large amount of demand, and the resulting soil diseases have become a serious problem. For such problems, conventionally, for example, in addition to the development of disease-resistant varieties and the use of rootstocks for next trees, measures such as steam sterilization, sterilization by solar heat treatment or chemical application have been taken. However, even though the soil diseases can be suppressed to some extent by any of the methods, the actual situation is that they cannot be suppressed sufficiently effectively. In contrast to such conventional means, research on controlling soil diseases using microorganisms such as Bacillus subtilis and actinomycetes has recently been actively conducted.

[0003]

However, the present situation is that neither control of soil diseases using microorganisms nor use of desired microbial antagonism due to various factors lurking in the soil has been sufficiently made. .. Therefore, in order to enhance the control effect of soil diseases, a search for useful microorganisms having a high exterminating ability against harmful microorganisms in soil and having high safety from the viewpoint of cultivating vegetables and the like that humans eat Is required. It is an object of the present invention to provide a novel microorganism that can meet the above-mentioned demand, and to provide a method for improving soil by inoculating the microorganism to control soil diseases.

[0004]

[Means for Solving the Problems] To obtain a microorganism that meets the above-mentioned purpose, the present inventors first focused on Bacillus natto, which has long been used for food and is considered to be highly safe, When conventional soybean broth or okara was inoculated with the commercially available Bacillus natto and grown, and the resulting culture was further inoculated into the soil, the Bacillus natto almost disappeared after 3 weeks and It turned out that it cannot be a preferred species of the microbiota. Here, in order to control soil diseases, the present inventors have the ability to control harmful microorganisms in soil, that is, have the ability to produce antibiotics, and become a priority species of the microflora in soil. Recognizing that it is necessary to use microorganisms to obtain,
After further intensive research, Bacillus subtilis TT8-2 obtained by the method described in the section "Means for creating microorganisms" described below.
The present inventors have found that the strain is a microorganism capable of achieving the intended purpose, and have completed the present invention. The present invention provides a method for improving soil, which comprises inoculating a soil with a culture of Bacillus sp. TT8-2, which has antifungal properties.

The present invention will be described in detail below. I. Method for creating microorganisms For the purpose of searching for Bacillus natto that has the ability to produce antibiotics, rice straw to which a large amount of Bacillus natto is attached is collected from all over the country.
I collected 00 bundles. From these rice straws, about 2700 strains of stringent microorganisms were isolated using 0.5% soybean agar agar medium. Using these microorganisms, natto was produced by a conventional method, and 750 strains that produced normal natto were further isolated. Next, these strains were coated with spores of white rot fungus (Rosellinianecatrix), which is a kind of plant pathogen 1.
% Of soybean juice agar was separately inoculated, and the degree of growth inhibition of the above-mentioned pathogenic bacteria in the grown natto colonies was examined. The widest 6 of the 750 strains around the colony
The strain having a growth inhibition zone of mm width was designated as TT8-2 strain. This TT8-2 strain was liquid-cultured with 2% soybean juice, the resulting culture was inoculated into soil, and changes in the microflora in the soil were examined. It accounted for about 95%.

II Identification of TT8-2 Strain TT8-2 strain was inoculated into steamed soybeans and
When fermented at 0 ° C., natto with good stringiness similar to that of commercially available natto was obtained. Unlike the conventional Bacillus natto, this TT8-2 strain is an antifungal bacterium because it inhibits the growth of Rosellinia necatrix and also the growth of ascomycetes belonging to Aspergillus, Penicillium and the like. Other mycological properties are those of conventional Bacillus natto (Rep. Natl. Food Res. Inst. No. 50, 18-21, 1987)
And soybean monthly report, December issue, 21-29 (1985)]. That is, this TT8-2 strain is an aerobic, Gram-staining, positive spore-forming bacillus, and the size of the bacterium (1 × 2 to 3 μ), the shape of the colony, and the optimum growth temperature (35).
〜45 ℃), fermentability of various sugars, GC content of DNA and other properties of Bergey's Manual 8th edition Bacillus subtilis (Bacillus subt
ilus), and it produces a mucilage and is auxotrophic for biotin.
us natto). This natto bacterium TT8
-2 strain (Bacillus sp. TT8-2) was submitted to Microorganism Research Institute, Microbiology Research Institute, Institute of Industrial Technology, on July 2, 1991.
Deposited as No. 8.

III Culture of TT8-2 strain and culture thereof
Soil Improving with Substances The culture of the TT8-2 strain of the present invention is generally, but not limited to, the production of soybean juice and tofu or fried food, which are wastes in the production of natto, miso and the like. Okara, which is a by-product of time, is preferably used. A typical culture method using these is described below.

(1) Liquid culture method The soybean-boiled broth obtained during the production of natto is used to obtain a solid content concentration of 2-3.
%, Adjusted to pH 6.5-7.0 with a NaOH solution, and then sterilized under pressure at 121 ° C. for 15 minutes. Preferably, the TT8-2 strain that has been separately cultivated is added to the place where the liquid temperature has dropped around 40 ° C., and sterilized air is aerated to the culture liquid, or while air is sent by a shaking method. Incubate at 20 to 50 ° C, preferably 40 ° C for 48 to 72 hours.

(2) Solid Culture Method Fresh tofu (tofu meal) is sterilized under pressure at 121 ° C. for 15 minutes,
Then, the TT8-2 strain that had been pre-cultured with the soybean boiling liquid obtained during the production of natto was added to this, and added to 25-40
Incubate in a constant temperature room at 48 ° C. for 48 to 72 hours. According to the method of the present invention, the culture thus obtained is inoculated into soil to improve the soil. The soil to be improved is, of course, a soil in which a predetermined vegetable or fruit tree is cultivated with a pathogen-free bacterium, and may be a continuous crop soil of these plants or a soil having a history of disease, and is not particularly limited. The term "inoculating" the culture with these soils is not limited to so-called "inoculation" as long as the culture can be applied to the soil, but "addition", "spraying",
In addition to “injection” and the like, application means such as “mixing” are also included. In the soil improved by the method of the present invention, as is clear from the results of the examples described below, the effect of controlling soil diseases is high, and particularly, the effect of controlling soil diseases caused by mold is extremely high.

[0010]

EXAMPLES The present invention will be described in more detail below with reference to examples. Example 1 (1) Cultivation of TT8-2 strain The soybean cooked broth obtained during the production of natto was diluted to a solid content concentration of 2%, the pH was adjusted to 6.8 with a NaOH solution, and then 1
It sterilized under pressure at 21 ° C. for 15 minutes. A seed culture of the TT8-2 strain, which had been separately cultured, was added to the place where the liquid temperature had dropped around 40 ° C., and the mixture was cultured at 40 ° C. for 48 hours while feeding air by the shaking method.

(2) Soil improvement method and effect test Rosellinia n. Fungus (Rosellinia n) having the following history of (a)
ecatrix) In a contaminated farmland, the culture solution obtained in (1) was injected into the soil by the irrigation method according to the test methods shown in (a) and (b) below, and the effect of reducing pathogens and the roots of transplanted young trees The presence or absence of Rao disease was investigated. The test results were as shown in (c) below. (A) A history of farmland In a farmland where death occurred due to white crest feather disease in a 30-year-old "apple", a young tree of "karin" 3rd year was transplanted as an alternative to dead tree, but 8 trees in 3 years Six of them died from Ras disease. A young tree of "Ume" was transplanted to this site and tested. (B) Test method After transplanting 8 saplings of "Ume" to Ra diseased area, a diameter of 3 cm and a depth of 20 at approximately equal intervals on the circumference of each tree with a radius of 30 cm.
Twenty cm holes were opened, and 5 liters of the culture solution was poured into the holes. (C) Progress (i) Changes in microorganisms in soil Microorganisms before injection Aerobic bacteria count 1.3 × 10 ⁸ cells / g Filament count 1.0 × 10 ⁵ cells / g 1 month after injection Aerobic bacteria Number 1.0 × 10 ⁸ cells / g TT8-2 95% or more Filamentous bacteria count 10 or less 6 months later Aerobic bacteria count 1.2 × 10 ⁸ cells / g TT8-2 60% or more Filamentous fungus count 1.0 * 10 ² pieces / g or less (ii) The vigor of "Ume" after 3 years has been good, and the attachment of white rot fungus to the roots has not been observed until now.

Example 2 (1) Culturing of TT8-2 Strain Fresh tofu (tofu meal) was sterilized under pressure at 121 ° C. for 15 minutes,
Then, the TT8-2 strain that had been pre-cultured with the soybean boiling liquid obtained during the production of natto was added to this, and the mixture was mixed at 40 ° C. for 4 hours.
It was cultured in a constant temperature room for 8 hours.

(2) Soil improvement and effect test In the above (1), 5% V / V of a culture grown to a bacterial count of 3 × 10 ⁸ or more was mixed with vegetable soil. Next, seeds of Chinese cabbage were sown in this soil to raise seedlings. The details of the effect test are as follows. Test crop: Chinese cabbage Test disease: Root-knot disease [Plant disease caused by Plasmodiophora brassicae, which is a type of mold in a broad sense] Test method: Standard seedling Seed in pathogen-free soil and transplanted 30 days after germination ,
80 days later, he was diagnosed with Rao disease. 5% V / V of the TT8-2 strain culture obtained in (1) above was mixed with the test seedling-free pathogen culture medium. Germinates like standard seedlings. Thirty days later, it was transplanted to soil with a history of Rao disease, and 80 days later, the disease of Chinese cabbage was determined. Result: Soil treatment concentrations subjected試株number incidence shares incidence untreated 0 30 23 77% TT8-2 cultures inoculated 5% V / V 30 8 26 %

[0014]

As described above, according to the soil improvement method of the present invention, not only a high control effect of soil diseases can be obtained, but also the microorganisms used for soil improvement have long been used for food and have high safety. Since it is a recognized Bacillus natto, it can provide an extremely good method for controlling soil diseases from the viewpoint of safety.

Claims (4)

[Claims] 1. A Bacillus subtilis TT8-2 strain (Ba) having antifungal properties.
Cillus sp. TT8-2) culture is inoculated into the soil to improve the soil. 2. As a culture, soybean juice and Bacillus subtilis TT8-
The method according to claim 1, wherein a culture obtained by inoculating and growing two strains is used. 3. Okara natto TT8-2 as a culture
The method according to claim 1, wherein a culture obtained by inoculating and growing a strain is used. 4. A Bacillus subtilis TT8-2 strain (Ba) having antifungal properties.
Cillus sp. TT8-2) Microbiology Research Institute No. 12338.