Patent Description:
Methane is the second largest greenhouse gas after carbon dioxide, and the annual contribution of methane to global warming is reported to be about <NUM>%. Major sources of methane production are paddy fields, ruminants, and natural wetlands, with estimated methane emissions from paddy field soils accounting for from <NUM> to <NUM>% of total emissions. As methods for reducing methane emissions in paddy fields, limiting the period of soil immersion (midsummer drainage) and reducing carbon inputs have been proposed. As another method for methane reduction, a method of treating paddy fields with <NUM>-bromoethanesulfonate (BES, <NUM>/kg), a specific inhibitor of methane-producing bacteria, during rice cultivation has been proposed, by which methane emissions were reduced by <NUM>% compared to a control area (see Non-patent Document <NUM>).

In the livestock industry, methane emissions from dairy cattle have been reduced by <NUM>% by treating feed with from <NUM> to <NUM>/kg of <NUM>-nitrooxypropanol (<NUM>-NOP), a methane-production inhibitor (see Patent Document <NUM>, Non-patent Document <NUM>).

<CIT> relates to a method for inhibiting methanogenesis and/or the growth of methanogens. The method comprises contacting a methanogenic archaea medium with a methane inhibiting amount and/or a growth inhibiting amount of a compound that specifically inhibits methane formation and inhibits the growth of methanogens. A method to increase feed efficiency in a ruminant is also provided via administering to the animal an effective rumen modifying amount of a compound that specifically inhibits methanogenesis. <CIT> relates to administering compounds to animals to suppress the formation of methane in the rumen. <CIT> relates to a methane generation inhibitor for ruminant characterized by comprising at least one ingredient selected from eucalyptus oil, peppermint oil, Japanese horseradish oil, cineole, iodine and cyclodextrin clathrates of these materials as an active ingredient as well as the feed composition for ruminant characterized in that the methane generation inhibitor is added thereto.

However, no previously known methane-production inhibitors have been put to practical use, and even today, development and practical application of superior methane-production inhibitors are still desired. The present invention has been made in view of such problems, and a principal object of the present invention is to provide use of a composition having a sustained methane-production inhibiting effect at a low amount of chemicals and a method for inhibiting methane production, in order to reduce undesirable methane production in paddy fields, lakes, marshes, and the like.

Specifically, in order to achieve the above-described objectives, the present inventor diligently conducted studies to find that application of a specific compound to places where methane is generated and to livestock feed reduces the amount of methane produced and maintains the effect, thereby completing the present invention.

The present invention, completed as described above, has the following gist.

Use of the composition according to the present invention can inhibit methane generation from a paddy field and a lake or marsh, a livestock production site, a compost or humus production site, a peatland, or the like for a long period of time, and in turn, is a useful invention as a measure to prevent global warming.

The composition used in the present invention to inhibit methane production contains one or more compounds selected from compounds represented by formula [I] as an effective ingredient:
<CHM>
where X represents an -OR<NUM> group, a hydroxyl group, or a halogen atom, Y represents an -OR<NUM> group or an -SO<NUM>R<NUM> group, R<NUM> represents a benzoyl group, R<NUM> represents a methylsulfonyl group or a chloromethylsulfonyl group, and R<NUM> represents a chloromethyl group or a hydroxymethyl group.

Suitable examples of the compounds represented by formula [I] include compounds represented by formulas [<NUM>-<NUM>] to [<NUM>-<NUM>]. <CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

The compound of formula [I-<NUM>] (hereinafter, referred to as "Compound I-<NUM>") is a compound known by the CAS number of <NUM>-<NUM>-<NUM> and can be synthesized by the method described in <CIT>. The compound of formula [<NUM>-<NUM>] (hereinafter, referred to as "Compound <NUM>-<NUM>") is a compound known by the <NPL>, and can be purchased from Chemieliva Pharmaceutical Co. The compound of formula [<NUM>-<NUM>] (hereinafter, referred to as "Compound <NUM>-<NUM>") is a compound known by the <NPL> and can be purchased from Sigma-Aldrich. The compound of formula [<NUM>-<NUM>] (hereinafter, referred to as "Compound <NUM>-<NUM>") is a compound known by the <NPL> and can be purchased from Sigma-Aldrich. The compound of formula [<NUM>-<NUM>] (hereinafter, referred to as "Compound <NUM>-<NUM>") is a compound known by the <NPL>and can be purchased from Azepine Ltd. The compound of formula [<NUM>-<NUM>] (hereinafter, referred to as "Compound I-<NUM>") is a compound known by the <NPL> and can be purchased from Chemieliva Pharmaceutical Co.

The methane-production inhibitor composition used in the present invention may be the compound represented by formula [I] by itself or may contain an additive component if necessary. Examples of such an additive component include a carrier such as a solid carrier or a liquid carrier, a surfactant, a binder, an adhesive agent, a thickener, a coloring agent, a spreading agent, a spreading agent, an anti-freezing agent, an anti-caking agent, a disintegrant, an anti-degradation agent, and a polymeric material.

The methane-production inhibitor composition used in the present invention may be used in any formulation, such as a liquid formulation, an emulsion concentrate, a wettable powder, a water-dispersible granule, a dust, an oil formulation, a flowable formulation, a granule formulation, a tablet formulation, a jumbo formulation, a suspoemulsion, a microcapsule, a paste, a seed coating formulation, a fumigant formulation, a smoking formulation, a Mametsubu (registered trademark name) formulation, a gelling formulation, a spraying formulation, a vulcanizing formulation, or a sheet formulation. These formulations can be prepared in the fields of pharmaceuticals, agrochemicals, or foods using the above-described additive components commonly used in formulation, using commonly known methods.

Since the methane-production inhibitor composition used in the present invention can inhibit methane production for a long period of time, the composition can be used at a variety of places where methane is generated such as a water system such as a paddy field and a lake or marsh, a peatland, a livestock production site, and a compost or humus production site, and is useful as a measure to prevent global warming, and is especially suitable for use in a place where methane production is high, for example, in paddy fields.

In the method for inhibiting methane production of the present invention, the methane-production inhibitor composition used in the present invention is applied to a water system where methane is generated, such as a paddy field or a lake or marsh, or to soil where methane is generated such as a peatland, thereby inhibiting methane production from the water system or the soil. Here, the lake or marsh is broadly defined as a body of water with shallow depth, such as a lake, a pond, a swamp, a stream, or a lagoon, for example, with a depth of <NUM> or less. The soil where methane is generated such as a peatland broadly refers to soil where methane is generated due to the presence of organic matter in a reduced state, such as a wetland soil, a swamp soil, or a paddy field soil.

The method for applying the methane-production inhibitor composition used in the present invention to a water system is not particularly limited, and it is sufficient to apply the compound represented by formula [I] in such a manner that the compound is dissolved or dispersed throughout the water system in which methane generation is to be inhibited, and this may be carried out using a commonly used application method, namely, a method such as spraying or pouring the methane-production inhibitor composition of the present invention as it is, or as a liquid suspended in a solvent such as water or acetone, throughout a water system.

The method for applying the methane-production inhibitor composition used in the present invention to methane-producing soil such as a peatland is not particularly limited, and the entire surface of the soil can be sprayed with the methane-production inhibitor composition of the present invention. It is preferable that the surface soil of the soil is mixed after the application, allowing the methane-production inhibitor composition used in the present invention to be mixed into the soil.

When the methane-production inhibitor composition used in the present invention is applied to a water system, such as a paddy field and a lake or marsh, or a peatland, the amount of the compound represented by formula [I] per <NUM> of dry soil is desirably in the range of from <NUM> to <NUM>,<NUM>, preferably from <NUM> to <NUM>,<NUM>, more preferably from <NUM> to <NUM>, and most preferably from <NUM> to <NUM>. The methane-production inhibitor composition used in the present invention applied in such a manner can effectively inhibit methane production when present in the surface soil to a depth of <NUM>.

When the above-described application amount is expressed in terms of an amount to be applied per <NUM> ha of area of a water system or soil to be applied, for example, in cases where the dry specific gravity (provisional specific gravity) of the soil is <NUM>, application of the compound represented by formula [I] in an amount in the range of from <NUM> to <NUM>,<NUM>,<NUM>, preferably from <NUM> to <NUM>,<NUM>,<NUM>, more preferably from <NUM> to <NUM>,<NUM>, and most preferably from <NUM> to <NUM>,<NUM> corresponds to the amount applied per dry soil as described above. However, it is known that the dry specific gravity (provisional specific gravity) of soil varies depending on the soil type, and for example, the dry specific gravity is about from <NUM> to <NUM> for sandy soils, from <NUM> to <NUM> for black granite soils, and from <NUM> to <NUM> for peat soils. When the dry specific gravity (provisional specific gravity) of soil at a location to be applied is considerably different from <NUM>, the above-described application amount per <NUM> ha of area may be multiplied by the value of the dry specific gravity (provisional specific gravity) of the soil.

In a water system such as a paddy field or a lake or marsh, the methane-production inhibitor composition used in the present invention can be applied to the surface of the water, and the compound represented by formula [I] is distributed mostly to the surface layer of soil in contact with the water, after which methane production from the soil will be inhibited. In this case, the depth of the water system is desirably not too deep, and in a lake or marsh, the water depth is preferably <NUM> or less, and more preferably <NUM> or less. Although, in paddy fields, the water depth is usually about from <NUM> to <NUM>, the composition can also be used in paddy fields managed with water depths as deep as <NUM>. When the methane-production inhibitor composition used in the present invention is applied to the surface of a paddy field or lake or marsh, the concentration of the compound represented by formula [I] in water may be, for example, from <NUM> to <NUM>,<NUM> ppm, and preferably from <NUM> to <NUM>,<NUM> ppm, more preferably from <NUM> to <NUM> ppm, and most preferably from <NUM> to <NUM> ppm. The amount of the methane-production inhibitor composition used in the present invention applied can also be calculated by the total water volume estimated from the area and water depth of a paddy field or a lake or marsh, such that the concentration of the compound represented by formula [I] in water is within the above-described range.

In the method for inhibiting methane production of the present invention, the methane-production inhibitor composition used in the present invention can also be mixed with livestock feed and fed to livestock to inhibit methane generation from livestock breath and excreta. The method for mixing the methane-production inhibitor composition used in the present invention with feed is not particularly limited, and the methane-production inhibitor composition used in the present invention may be mixed with feed prior to feeding to livestock. In this case, the amount of the methane-production inhibitor composition used in the present invention to be applied may be determined by calculating the amount of the compound represented by formula [I] per <NUM> of feed to be in the range of from <NUM> to <NUM>,<NUM>, preferably from <NUM> to <NUM>,<NUM>, further preferably from <NUM> to <NUM>, and most preferably from <NUM> to <NUM>.

Furthermore, in the method for inhibiting methane production, the methane-production inhibitor composition used in the present invention can be applied to a compost or leaf mold material during production of the compost or leaf mold, thereby inhibiting generation of methane during production of the compost or leaf mold and from the produced compost or leaf mold. The method for applying the methane-production inhibitor composition used in the present invention for this purpose is not particularly limited, and the methane-production inhibitor composition used in the present invention can be mixed with a compost or leaf mold material and fermented to inhibit methane produced in a fermentation process of compost or leaf mold or methane produced from fully ripe compost or fully ripe leaf mold. In this case, the amount of methane-production inhibitor composition used in the present invention to be applied may be calculated such that the amount of the compound represented by formula [I] per <NUM> of a compost or leaf mold material is in the range of from <NUM> to <NUM>,<NUM>, preferably from <NUM> to <NUM>,<NUM>, more preferably from <NUM> to <NUM>, and most preferably from <NUM> to <NUM>.

Hereinafter, an effect of the methane-production inhibitor used in the present invention will be described with Test Examples, but the present invention is not restricted by these Test Examples in any way.

In a glass vial (<NUM> volume) for headspace analysis, <NUM> of paddy field soil (provisional specific gravity <NUM>/cm<NUM>) was weighed, and <NUM> of distilled water was added. In this flooded soil, a plot to which <NUM>µL of <NUM> ppm Compound I-<NUM>-containing acetone solution was added (<NUM>/kg dry soil (equivalent to <NUM>/ha)) was provided as Example <NUM>, and a plot to which <NUM>µL of <NUM> ppm Compound I-<NUM>-containing acetone solution was added (<NUM>/kg dry soil (equivalent to <NUM>/ha)) and a plot to which <NUM>µL of <NUM> ppm Compound I-<NUM>-containing acetone solution was added (<NUM>/kg dry soil (equivalent to <NUM>/ha)) were provided as Examples <NUM> and <NUM>. As Comparative Example <NUM>, an untreated plot to which <NUM>µL of acetone was added was provided. After <NUM>µL of a culture solution of paddy field soil microorganisms was added to these glass vials, the vials were tightly sealed using septum and aluminum caps, and allowed to stand at <NUM> for static incubation. After <NUM> and <NUM> days of incubation treatment, <NUM> of gas was collected from a headspace in a glass vial sample using a gas tight syringe and analyzed for methane production by gas chromatography (GC). The results are shown in Table <NUM>. The amount treatment (g) per <NUM> ha was converted according to the OECD Guideline Test No. <NUM> issued in <NUM>, based on the provisional specific gravity of the paddy field soil used.

In Test Example <NUM>, compared to an untreated plot (Comparative Example <NUM>), the methane-production amount was reduced in the Compound I-<NUM> treatment plot (Example <NUM>) at <NUM>/kg dry soil, and a higher reduction effect was achieved at <NUM>/kg dry soil and above (Examples <NUM> and <NUM>).

In a glass vial (<NUM> volume) for headspace analysis, <NUM> of paddy field soil (provisional specific gravity <NUM>/cm<NUM>) was weighed, and <NUM> of distilled water was added. In this flooded soil, plots to which <NUM>µL of acetone solution containing <NUM> ppm of the compounds listed in Table <NUM> below were added (<NUM>/kg dry soil (equivalent to <NUM>/ha)), respectively, were provided as Examples <NUM> to <NUM>. As Comparative Example <NUM>, an untreated plot to which <NUM>µL of acetone was added was provided. After <NUM>µL of a culture solution of paddy field soil microorganisms was added to these glass vials, the vials were tightly sealed using septum and aluminum caps, and allowed to stand at <NUM> for static incubation. After <NUM> and <NUM> days of incubation treatment, <NUM> of gas was collected from a headspace in a glass vial sample using a gas tight syringe and analyzed for methane production by gas chromatography (GC). The results are shown in Table <NUM>.

In Test Example <NUM>, the methane-production amount was reduced in all of the various methane-production inhibitor treatment plots (Examples <NUM> to <NUM>) compared to the untreated plot (Comparative Example <NUM>). In the <NUM>/kg dry soil treatment, Compound I-<NUM> and Compound I-<NUM> showed a particularly high reduction effect (Examples <NUM> and <NUM>).

In a glass vial (<NUM> volume) for headspace analysis, <NUM> of paddy field soil (provisional specific gravity <NUM>/cm<NUM>) was weighed, and <NUM> of distilled water was added. In this flooded soil, a plot to which <NUM>µL of acetone solution containing <NUM> ppm of Compound I-<NUM> was added (<NUM>/kg dry soil (equivalent to <NUM>/ha)) is provided as Example <NUM>, a plot to which <NUM>µL of an aqueous solution containing <NUM> ppm of BES (a comparative compound) and acetone was added (<NUM>/kg dry soil) is provided as Comparative Example <NUM>, and an untreated plot to which <NUM>µL of acetone was added is provided as Comparative Example <NUM>. After <NUM>µL of a culture solution of paddy field soil microorganisms was added to these glass vials, the vials were tightly sealed using septum and aluminum caps, and allowed to stand at <NUM> for static incubation. After <NUM> and <NUM> days of incubation treatment, <NUM> of gas was collected from a headspace in a glass vial sample using a gas tight syringe and analyzed for methane production by gas chromatography (GC). The results are shown in Table <NUM>. The comparative compound, BES (<NPL>; <NUM>-Bromoethanesulfonate), is an existing methane-production inhibitor and a product manufactured by Tokyo Chemical Industry Co.

Claim 1:
Use of a composition for the inhibition of methane production, characterized by comprising one or more compounds selected from compounds represented by formula [I] as an effective ingredient:
<CHM>
where X represents an -OR<NUM> group, a hydroxyl group, or a halogen atom, Y represents an - OR<NUM> group or an -SO<NUM>R<NUM> group, R<NUM> represents a benzoyl group, R<NUM> represents a methylsulfonyl group or a chloromethylsulfonyl group, and R<NUM> represents a chloromethyl group or a hydroxymethyl group.