JP5044167B2 - Soil treatment agent and soil treatment method - Google Patents

Description

  The present invention relates to a soil treatment agent and a soil treatment method, and more particularly to a soil treatment agent containing a culture of a specific microorganism or a treatment product thereof, and a soil treatment method for applying the soil treatment agent to soil.

  There is a dry spot as a trouble that occurs in turf grass such as green of a golf course, especially bent grass. This is one of the important matters in turfgrass management because growth inhibition occurs on the turfgrass surface in spots, and as it progresses, the turfgrasses die.

  Dry spots are particularly likely to occur when turfgrass is grown on sandy soil, but the soil on the turfgrass surface is hydrophobized, making it impossible for the soil to retain the water necessary for turfgrass growth. Will die. Hydrophobic soil is caused by the formation of a hydrophobic substance in the process of breaking down thatch layer, peat moss, or other organic matter on which litter after mowing has been accumulated by the action of microorganisms. The soil is made hydrophobic because it covers the surface of the particles. Hydrophobic soil has extremely poor water permeability, so that not only water is hardly retained in the soil, but also water is not permeated even when water is sprayed and remains dry.

  In response to dry spots, in addition to careful removal of the thatch layer and appropriate water sprinkling management, a soil penetrant is generally used to improve the water permeability of soil that has become hydrophobic. The method of applying to the soil of turf grass surface is widely performed. Many of these soil penetrants are mainly composed of, for example, a nonionic surfactant (Patent Document 1, Patent Document 2, and Patent Document 3).

Japanese Patent Laid-Open No. 10-60437 JP-A-11-256160 JP 2002-20749 A

  However, removal of litter after lawn mowing and sufficient watering management require a great deal of labor, but it is difficult to completely suppress the occurrence of dry spots. Moreover, in the present condition, sufficient effect is not necessarily acquired with the coping method which sprays a soil penetrant. On the other hand, in recent years, there has been an increasing social interest in releasing chemicals into the natural environment, and legal regulations are becoming stronger.

  The present invention has been made in view of such a situation, and is excellent in the effect of suppressing the hydrophobization of the soil and the effect of improving the water permeability to the hydrophobized soil by applying to the soil. An object of the present invention is to provide a soil treatment agent and a soil treatment method that have high safety.

As a result of intensive studies on the water permeability improvement effect of microbial products on the soil, the present inventors have found that a specific microbial product suppresses the hydrophobicity of the soil, as well as the hydrophobicized soil. As a result, the present invention has been completed.
That is, the present invention includes the following inventions.
[1] A soil treatment agent containing a culture of microorganisms belonging to the genus Gordonia or a treated product thereof.
[2] The soil treatment agent according to [1], wherein the culture or a treated product thereof includes a complex lipid produced by the microorganism.
[3] The soil treatment agent according to [2], wherein the complex lipid includes a neutral sugar and a fatty acid as main components.
[4] The soil treatment agent according to any one of [1] to [3], wherein the microorganism is Gordonia sp. JE1058 (FERM BP-7406).
[5] The soil treatment agent according to any one of [1] to [4], which is for turfgrass.
[6] A soil treatment method comprising applying the soil treatment agent according to any one of [1] to [5] to soil.
[7] The soil treatment method according to [6], wherein the soil is turf grass.

  According to the present invention, it is possible to provide a soil treatment agent and a soil treatment method that effectively suppress hydrophobization of soil and effectively improve water permeability of soil that has been hydrophobized and deteriorated in water permeability. Further, since the soil treatment agent of the present invention uses a microbial product or a treated product thereof, the biodegradability and safety are high, and the influence on the environment is small.

  The soil treatment agent of the present invention contains a culture of microorganisms belonging to the genus Gordonia or a treated product thereof. The microorganism used in the present invention is not particularly limited as long as it is a microorganism belonging to the genus Gordonia, and has the ability to produce complex lipids mainly composed of neutral sugars and fatty acids, for example, Gordonia sp. JE1058 (FERM BP-7406), Gordonia polyisoprenivorans (for example, DSM 44266, DSM 44302, NCIMB 13616).

  Gordonia sp. JE1058 (FERM BP-7406) is deposited at the National Institute of Advanced Industrial Science and Technology, Patent Biological Deposit Center (Tsukuba Center Central 6th 1-1 1-1 Higashi 1-chome Tsukuba, Ibaraki Prefecture). Gordonia polyisoprenivorans DSM 44266 and Gordonia polyisoprenivorans DSM 44302 are deposited with DSMZ (Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH). Gordonia polyisoprenivorans NCIMB 13616 is deposited with NCIMB (National Collections of Industrial Food and Marine Bacteria (incorporating the NCFB), NCIMB Ltd.).

  Microorganisms used in the present invention can be easily selected by culturing microorganisms belonging to the genus Gordonia and confirming that they have the ability to produce complex lipids containing neutral sugars and fatty acids as main components.

  The culture or treated product of the microorganism used in the present invention preferably contains a complex lipid (for example, glycolipid) produced by the microorganism, and further contains a neutral sugar and a fatty acid as main components. Those containing complex lipids (eg, glycolipids) are preferred.

  The culture used in the present invention can be produced by aerobically culturing microorganisms belonging to the genus Gordonia, for example, in a medium containing normal paraffin as a raw material carbon source.

  In the present invention, a culture or a processed product thereof can be produced using a mutant strain obtained by mutagenizing the microorganism. The method of mutagenesis treatment is not particularly limited as long as it induces mutation. For example, chemical methods using mutation agents such as N-methyl-N′-nitro-N-nitrosoguanidine, ethyl methanesulfonate, physical methods such as ultraviolet irradiation and X-ray irradiation, biological methods such as genetic recombination and transposon A method or the like can be used. This mutagenesis treatment may be performed once, or two or more mutagenesis treatments may be performed such that the mutant obtained by this mutagenesis treatment is further mutagenized.

  The medium is not particularly limited as long as microorganisms belonging to the genus Gordonia can grow. As a raw material carbon source, C10-18 normal paraffin, chain hydrocarbons such as olefins, C10-18 fatty acids, C10-18 fatty acid esters, C10-18 carbons in terms of productivity. Fats and oils composed of these fatty acids are preferred, and normal paraffin is more preferred. Examples of such normal paraffins include decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane and octadecane.

  As other medium components, those commonly used for culturing microorganisms, such as nitrogen sources and inorganic salts, can be used. If necessary, various extracts, vitamins and the like can be used.

  The pH and temperature during the cultivation are not particularly limited as long as microorganisms belonging to the genus Gordonia grow and produce a product having an action of improving the water permeability of the soil, but the pH is usually 5 to 10, The temperature is 20-35 ° C. The culture time may be selected so as to optimize the production of a product having an effect of improving the water permeability of the soil, and is not particularly limited. Usually, the culture is performed aerobically for 2 to 10 days. .

  In the present invention, usually, microbial cells are removed from the culture solution obtained as described above by a known method such as centrifugation or filtration, and then the supernatant is concentrated by ultrafiltration. What dried the liquid by well-known methods, such as freeze-drying, is used as a soil treatment agent, for example. In addition, the culture solution obtained as described above can be used as a soil treatment agent by drying by a known method while containing microorganisms, or by removing microbial cells from the culture solution.

  If necessary, in addition to the above-described operation, for example, an organic solvent such as pentane or hexane may be used to remove the normal paraffin or the like carried over from the culture solution.

  In the present invention, depending on the purpose, a culture solution, a culture such as a dried product thereof, or a treatment after removing microbial cells from the culture solution and then drying, a solution obtained by removing microbial cells from the culture solution, or the like. A thing can be used suitably.

  The culture of the present invention or a processed product thereof contains a neutral sugar and a fatty acid as main components. The composition of these neutral sugars and fatty acids varies depending on the culture conditions and the like, but usually shows the following composition.

  The content of neutral sugar in the processed product of the culture (solid content after removal of the cells) is usually 20 to 45% by weight, and glucose, galactose and mannose are recognized as the main components as constituent sugars. It is done. Usually, it contains 15 to 28% by weight of glucose, 3 to 10% by weight of galactose, and 0.2 to 3% by weight of mannose. In addition, rhamnose may be further included. The content of neutral sugars can be easily determined by the orcinol-sulfuric acid method, and the composition and content of neutral sugars can be easily determined by hydrolysis with acid followed by HPLC analysis.

  The content of fatty acid in the processed product of the culture (solid content after removal of the cells) is usually 20 to 50% by weight. The type of fatty acid component and the number of carbons differ depending on the type of raw material carbon source used when culturing the microorganism. For example, when tetradecane, which is a normal paraffin having 14 carbon atoms, is used as the raw material carbon source, octanoic acid, decane Acids, 3-hydroxydecanoic acid and 3-hydroxydodecanoic acid are recognized as the main constituent fatty acids. An example of the content of these fatty acids is 6 to 12% by weight of octanoic acid, 3 to 11% by weight of decanoic acid, 1 to 5% by weight of 3-hydroxydecanoic acid, and 1 to 7 of 3-hydroxydodecanoic acid. % By weight. The content of fatty acids in the treated product of the culture is determined by extracting the aqueous solution obtained by alkaline hydrolysis of the treated product of the culture with ether, removing the ether solubles, acidifying the aqueous solution, and then extracting with ether. The fatty acid composition is obtained by measuring the weight of the extracted fatty acid, and the constituent fatty acid composition is obtained by subjecting the fatty acid obtained by ether extraction under acidic conditions to methyl esterification by a conventional method and analyzing by gas chromatography. Each can be easily obtained.

The processed product of the culture of the present invention (solid content after removal of the cells) is freed of fatty acid by alkaline hydrolysis, freed of sugar by acidolysis, and converted to an ester bond by infrared spectrum (FT-IR). Since absorption is observed at a peculiar 1735 cm ⁻¹ , it can be presumed that a complex lipid (for example, glycolipid) containing neutral sugars and fatty acids as main components is the main component.

  Furthermore, the main component of this complex lipid (for example, glycolipids) is fixed in a thin-layer chromatograph, for example, by removing methanol from an extract obtained by extracting the treated product of the culture with methanol and drying it. When the phase is developed as silica gel and the mobile phase is developed as chloroform: methanol: water (for example, 60: 30: 2), it can be confirmed as a spot developed above the origin.

  The culture of the present invention or the treated product thereof can be suitably used as a soil treatment agent because it is excellent in the performance of suppressing soil hydrophobicity and improving the water permeability of soil.

  Hydrophobic soil, which causes dry spots in golf course greens, is caused by various organic substances such as litter after mowing, dead leaves of turfgrass, or peat moss, which is rhizosphere soil, due to the action of microorganisms. Hydrophobic organic matter generated by conversion or decomposition occurs when soil particles are coated. Hydrophobized soil has a marked deterioration in water permeability and repels water, so that water retention of the soil is significantly lost and a dry soil layer is formed. When the soil is in this state, it will no longer be able to absorb enough water from the roots, because turfgrass will not be able to absorb enough water from the roots. Then turfgrass will die. Such hydrophobized soil often occurs in a range from the surface to about 5 cm below the surface of the earth. For example, when it becomes a depth of 7 to 8 cm or more below the surface of the earth, it is not so hydrophobized.

  In addition, the degree of hydrophobicity varies depending on the type of soil, and it is known that the higher the percentage of sand contained in the soil, the higher the risk of dry spots. The generation of dry spots is a particular problem. In the present invention, the soil on which turfgrass is grown is sometimes referred to as soil, including only sand or sand.

  The types of turfgrass include warm regions such as Bermudagrass and centipeatgrass, and cold regions such as bluegrass, ryegrass, tall fescue, fine fescue and bentgrass. Among these types, it is said that dry spots are likely to occur in bentgrass and bermudagrass.

  The culture obtained as described above or a treated product thereof is usually applied as a soil treatment agent to soil in which dry spots are generated and / or which may be generated by dissolving in water. For example, this aqueous solution is sprayed on the turf grass surface as described above.

The soil treatment agent of the present invention is preferably used in a concentration range of 0.01 g / L to 20 g / L, and more preferably 0.1 g / L to 10 g / L when the soil treatment agent is a treated product of the culture. This soil treatment agent solution is sprayed on the soil using a sprayer, a sprinkler or the like. The application amount is preferably 0.5 to 5 L / m ^{2, and} more preferably 1 to 3 L / m ² . If necessary, water spraying may be further performed so that the soil treatment agent reaches a depth where the hydrophobized soil layer exists.

  The reason why the soil treatment agent of the present invention can prevent or improve the soil permeability due to the hydrophobicity of the soil such as dry spots and the adverse effect due to the deterioration of the water retention is as follows. It is thought that the affinity between soil particles and water is improved by covering the water, and water easily penetrates into the voids between the soil particles. Furthermore, since the affinity between soil particles and water is increased, it is considered that the water that has permeated into the soil is retained in the gaps between the soil particles.

  In the soil treatment agent of the present invention, if necessary, a nonionic surfactant, an amphoteric surfactant, a bactericide, an inorganic salt, and the like are appropriately blended so as not to impair the effects of the present invention. Also good.

  As turf grass surface, it can be used suitably for turf grass surfaces such as golf course green, fairway, tee ground, but not limited to this, it is also used for turf grass surfaces such as parks, gardens, playgrounds, soccer courts, athletic fields, etc. it can.

  The soil treatment agent of the present invention is mainly used for turfgrass, but can exert excellent effects when applied to soil where soil hydrophobization inhibiting effect and soil water permeability improving effect are desired, for example, It can also be applied to nurseries and cultivation soils used for cultivation of vegetables, fruit trees, flower buds, and slopes where soil runoff due to rainwater is a problem.

  Hereinafter, the present invention will be described with reference to examples.

[Analysis method]
In the following, neutral sugars and fatty acids were analyzed as follows.
(1) Analysis of neutral sugars The content of neutral sugars was analyzed by the orcinol-sulfuric acid method. For qualitative and quantitative analysis of the neutral sugar composition, the sample was hydrolyzed in 2N trifluoroacetic acid at 100 ° C for 6 hours, then dried under reduced pressure, and the dried product was dissolved in distilled water. It was measured from a calibration curve of various neutral sugars by HPLC analysis by the method.
Column: TSK-gel sugerAXG 15 cm x 4.6 mm I.D., column temperature: 70 ° C
Mobile phase: 0.5 M potassium borate buffer (pH 8.7), flow rate: 0.4 ml / min
Post-column labeling: 1% arginine / 3% boric acid, reaction temperature: 150 ° C
Detection wavelength: EX320nm, EM430nm

(2) Analysis of fatty acid The content of fatty acid was measured as follows. The sample was hydrolyzed in 1N aqueous sodium hydroxide solution and then extracted with ether to remove the ether extract. The aqueous layer after extraction with ether was acidified with hydrochloric acid (pH 2-3), and extracted again with ether. The ether layer was dehydrated with anhydrous sodium sulfate, the ether was removed by evaporation, and the weight of the residue was measured. From the weight of the residue, the fatty acid content in the sample was calculated. The residue was further methylated with diazomethane and analyzed by gas chromatography to analyze the fatty acid composition.

[Preparation Example]
(Preparation of soil treatment agent)
Using Gordonia sp. JE1058 strain, a platinum loop was inoculated into 50 ml of a medium containing 20 g / L of monosodium glutamate, 10 g / L of yeast extract, and 15% by volume of n-tetradecane. Culture was performed for 2 days.

  Next, a culture medium of 2.5L having the same composition as described above was put into a 5L jar fermenter, and the culture solution was inoculated, and the culture was performed for 7 days under aeration conditions at a temperature of 30 ° C. and a stirring speed of 1000 rpm. Went.

  After completion of the culture, the culture solution was diluted 2 times with water, adjusted to pH 10, and then the cells were removed by centrifugation. Further, the pH was readjusted to 8, concentrated by ultrafiltration, and lyophilized. The dried powder was washed with hexane and dried under reduced pressure to obtain 107 g of a processed product of the culture.

  Table 1 shows the analysis results of the processed product of the obtained culture broth.

[Examples 1 and 2, Comparative Example 1]
The treated product of the culture obtained as described above was dissolved in distilled water at concentrations of 2 g / L and 5 g / L to prepare a soil treatment agent. This soil treatment agent was sprayed on the golf course green at a spread rate of 1 L / m ² , and 3 days after the application of the soil treatment agent, a soil core was collected using a soil sampler. One drop of distilled water was dropped with a dropper at a depth of 5 cm in 1 cm increments from the ground surface, and the time until the distilled water soaked into the soil core was measured. Each penetration time (second) is shown in Table 2. In addition, it has shown that water osmosis | permeation to soil is so favorable that infiltration time is short.

[Examples 3 to 4, Comparative Example 2]
Similarly, the penetration time of distilled water about the soil core 20 days after spraying of the soil treatment agent was measured. Each penetration time (second) is shown in Table 3.

[Comparative Example 3]
3 ml of a commercially available soil improvement agent for dry spots (containing a nonionic synthetic surfactant) was diluted to 1 L with water, and this aqueous solution was sprayed on the golf course green at a spraying amount of 1 L / m ² . The soil core 20 days after application | coating was extract | collected and the penetration time of distilled water was measured similarly. The results are shown in Table 4.

Claims (6)

A soil treatment agent comprising a culture of Gordonia sp. JE1058 (FERM BP-7406) or a treated product thereof. A soil treatment agent for turfgrass comprising a culture of microorganisms belonging to the genus Gordonia or a treated product thereof. The soil treatment agent according to claim 1 or 2, wherein the culture or a treated product thereof contains a complex lipid produced by the microorganism. The soil treatment agent according to claim 3, wherein the complex lipid contains a neutral sugar and a fatty acid as main components. A soil treatment method comprising applying the soil treatment agent according to claim 1 to soil. A soil treatment method comprising applying the soil treatment agent according to any one of claims 1 to 5 to soil of a turf grass surface.