JP2002114609A - Killing agent for ameba and method for suppressing ameba in water system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a killing agent for amebas effective even against the amebas converted into cysts, and to provide a method for microbial removal of bacteria of the genus Legionella which is effective even in a water system comprising the bacteria of the genus Legionella under conditions for converting the amebas into the cysts coexisting with the bacteria. SOLUTION: This killing agent for the amebas comprises a fatty acid dimethylamide represented by the formula (1) RCO-N(CH3)2 (1) (wherein R is a >=5 and a <=23C chain hydrocarbon group).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention eliminates Legionella bacteria in a cold / hot water system or a heat storage water system, such as circulating cooling water for refrigeration systems and air conditioning facilities and circulating hot water for 24-hour baths, and prevents their growth. The present invention relates to an amoeba killer that suppresses amoeba in a water system.

[0002]

2. Description of the Related Art Legionella spp. Surviving in water systems is known as a pathogen of Legionella pneumonia. And various methods have been proposed for their eradication.

[0003] However, even in the case of a drug having a sufficient effect on Legionella spp. In experiments in a laboratory, a sufficient effect has not always been obtained in an actual aqueous system.

[0004] The present inventors have studied in detail the difference in efficacy between the laboratory and the actual environment water system. In the actual environment water system, suppression and control of amoeba are effective in eliminating Legionella spp. It turned out to be indispensable.

It is known that Legionella spp. Infests and proliferates on bacterial predatory protozoa such as amoeba in real environmental waters. However, the conventional bacteria elimination technique of Legionella spp. The problem was that they did not focus on the ecological characteristics of fungal growth.

[0006] As a result of intensive studies by the present inventors, it has been found that Legionella spp. Can survive and proliferate in the presence of amoeba even in an environment where it cannot survive on its own. understood.

That is, considering a case where a fungicide for Legionella is added to an aqueous system in which Legionella and Amoeba are suitably grown, if the fungicide does not affect the growth of Amoebae, Because amoeba is normally active, it has a certain probability of predating Legionella spp. Legionella spp. Preyed by amoeba grows in large quantities without being affected by bactericides in the body of the amoeba and without being digested by the amoeba. Come. Legionella spp. That has appeared in the water system is gradually killed by exposure to the fungicide, but Legionella spp. Preyed by amoeba before dying will grow again in the amoeba body.

[0008] Therefore, in order to effectively eliminate Legionella spp. In such an aqueous system, it is necessary to suppress the amoeba itself, which is a site for the growth of Legionella spp.

Furthermore, recently, amoeba not only becomes a host of Legionella spp., But also enters the brain nasally and causes highly lethal meningoencephalitis, or mainly produces corneas of contact lens users. It is becoming known to have pathogenicity, such as causing fire.

A method effective for suppressing such amoeba,
Alternatively, the present inventors have proposed in Patent Application No. 10-167593 or the like an effective method for removing Legionella spp. When an amoeba and Legionella spp. Coexist.

[0011]

However, as a result of recent detailed studies, it has been found that these techniques are inadequate in suppressing amoeba. In other words, if the amoeba changes environment and becomes unsuitable for survival with normal vegetative bodies,
It becomes a cyst and becomes a vegetative body when it returns to an environment suitable for its survival. However, it has been found that the conventional technique cannot provide a sufficient effect on the amoeba in the cyst state.

The present invention solves the above-mentioned conventional problems, that is, an amoeba killing agent which is effective in a short time even when a low concentration of amoeba is added to a cyst state amoeba, and the amoeba killing agent. It is an object of the present invention to provide a method for controlling amoeba in an aqueous system using an agent, and a disinfectant and a method for disinfecting Legionella spp. That are effective even when coexisting with amoeba in a cyst state.

[0013]

Means for Solving the Problems The present inventors have conducted a detailed study on fatty acid dimethylamide represented by the following general formula (1), which is a known substance as a dispersant for microorganisms in a cooling water system. However, by accident, the present inventors have found that this substance has a specific effect not only on the control of Legionella spp. And amoeba in the vegetative state but also on the control of amoeba in the cyst state, leading to the present invention.

That is, the amoebicide according to the present invention is an amoebicide containing dimethyl amide of a fatty acid represented by the general formula (1).

[0015]

Embedded image RCO—N (CH ₃ ) ₂ (1) wherein R is a chain hydrocarbon group having 5 to 23 carbon atoms.

Further, the method for suppressing amoeba in an aqueous system according to the present invention solves the above-mentioned problems.
A method for suppressing amoeba in an aqueous system, comprising adding dimethylamide of a fatty acid represented by the general formula (1) to an aqueous system in which the amoeba is alive.

[0017]

Embedded image RCO—N (CH ₃ ) ₂ (1) wherein R is a chain hydrocarbon group having 5 to 23 carbon atoms.

[0018] With such a configuration, even in the case of addition at a low concentration, it has a killing effect on amoeba in a vegetative state in a short time, and is effective in an ameba that has become cysts. The amoeba killing agent or the method for suppressing amoeba can be used.

The disinfectant for Legionella according to the present invention contains a dimethylamide of a fatty acid represented by the general formula (1), as described in claim 3. It is.

[0020]

Embedded image RCO—N (CH ₃ ) ₂ (1) wherein R is a chain hydrocarbon group having 5 to 23 carbon atoms.

According to the method of the present invention for removing bacteria of the genus Legionella in an aqueous system, the fatty acid represented by the general formula (1) is added to an aqueous system in which the genus Legionella is alive. A method for removing Legionella spp. From an aqueous system, comprising adding dimethylamide.

[0022]

Embedded image RCO—N (CH ₃ ) ₂ (1) wherein R is a chain hydrocarbon group having 5 to 23 carbon atoms.

With this configuration, even when amoeba coexists in the water system, it is possible to remove Legionella spp. Effectively at a low concentration and in a short time.

Furthermore, the method for removing bacteria of the genus Legionella in an aqueous system according to the present invention is, as described in claim 5, an ameba trophozoite and an amoeba cyst in an aqueous system in which the genus Legionella and amoeba coexist. A drug capable of killing both is added so that the number of amoeba in the aqueous system becomes less than 10 per 100 mL, thereby removing Legionella spp. By removing Legionella spp. This is a reliable method for eliminating Legionella spp., And enables stable eradication over a long period of time with a small amount of drug.

If the agent capable of killing both the amoeba trophoblast and the amoeba cyst is a dimethylamide of a fatty acid represented by the general formula (1) as described in claim 6, it can be rapidly added even at a low concentration. It is possible to remove bacteria of the genus Legionella.

[0026]

Embedded image RCO—N (CH ₃ ) ₂ (1) wherein R is a chain hydrocarbon group having 5 to 23 carbon atoms.

BEST MODE FOR CARRYING OUT THE INVENTION In the amoebicide of the present invention, it is necessary to use a fatty acid dimethylamide represented by the general formula (1).

[0027]

Embedded image RCO—N (CH ₃ ) ₂ (1) wherein R is a chain hydrocarbon group having 5 to 23 carbon atoms.

Although the details are unknown, it is not possible to use -CO-N (C in the fatty acid dimethylamide represented by the general formula (1).
H ₃ ) ₂ is considered to be a characteristic group having a bactericidal / killing action on amoeba (vegetative body, cyst) and Legionella spp., And R is a chain type having 5 to 23 carbon atoms. The hydrocarbon group can be appropriately selected depending on the target organism to be killed.
Is an alkenyl group having 5 to 23 carbon atoms and is particularly effective for killing both amoeba and Legionella spp. Dimethylamide is available from Bachman Laboratories and the like.

On the other hand, when the dimethylamide is substituted with an ethyl group, hydrogen, or the like instead of the methyl group, the effects of the present invention cannot be obtained, and R in the formula (1) has four or less carbon atoms. Alternatively, the effect of the present invention cannot be obtained with a chain hydrocarbon group having 24 or more carbon atoms.

Since the fatty acid dimethylamide represented by the general formula (1) has a killing effect on other bacteria and algae, it can be used as a general water-based disinfectant / algicide. it can.

In the present invention, the amount of the fatty acid dimethylamide represented by the general formula (1) added to the target aqueous system is usually 1 mg.
/ L or more and 1000 mg / L or less.
There is no particular limitation on the method of addition, and it may be added intermittently to the target water system at intervals of several days to about one month, or continuously added so as to maintain the concentration in the water system at a certain level or more. May be.

In the present invention, when the fatty acid dimethylamide represented by the general formula (1) is added to the target aqueous system, other components such as an acrylic acid polymer, a maleic acid polymer, a methacrylic acid polymer, and a sulfone Scale inhibitors such as acid polymers, phosphoric acid polymers, itaconic acid polymers, isobutylene polymers, phosphonic acids, phosphinic acids, or water-soluble salts thereof, for example, 5-chloro-2-methyl-4- Isothiazolin-3-one, 2-methyl-4
Isothiazolone compounds such as -isothiazolin-3-one and 1,2-benzoisothiazolin-3-one; aldehydes such as glutaraldehyde and phthalaldehyde; for example, hydrogen peroxide, hydrazine, chlorine-based germicides (hypochlorous acid) Sodium), bromine-based germicides and iodine-type bactericides, thiocyanate-based compounds such as dithiol-based compounds, methylenebisthiocyanate, thione-based polymers, quaternary ammonium salt-based compounds, etc. Amine compounds such as diethylenetriamine, for example, nitrilotriacetic acid, ethylenediaminetetraacetic acid, aminocarboxylic acid compounds such as diethylenetriaminepentaacetic acid, for example, gluconic acid, citric acid, oxalic acid, formic acid, tartaric acid, phytic acid, succinic acid,
Various water treatment agents, such as organic carboxylic acids such as lactic acid, can be used in combination. In some cases, these water treatment agents are mixed in advance with the fatty acid dimethylamide represented by the general formula (1). May be.

The anticorrosive is selected from tolyltriazole, benzotriazole, mercaptobenzothiazole, molybdic acid and its salts, zinc and its salts, phosphoric acid and its salts, nitrous acid and its salts, sulfurous acid and its salts, and the like. One or more components may be added.

[0034]

Embodiments of the present invention will be described below. (Preparation of agar medium coated with Escherichia coli) Agar for bacterial examination was dissolved in ion-exchanged water to a concentration of 1.5% (w / v), sterilized at 121 ° C for 15 minutes, and placed in a sterilized petri dish having a diameter of 90 mm. An agar plate was prepared by dispensing ２０20 mL.
Next, an appropriate amount of Escherichia coli cultured separately on a standard agar plate medium was collected, suspended in sterile ion-exchanged water to prepare a concentrated Escherichia coli suspension, which was heated at 60 ° C. for 1 hour, and then sterilized. It diluted so that OD might be set to 0.5 with ion-exchange water. Then, 0.3 mL of this solution was applied to the entire surface of the agar plate, and dried so that Escherichia coli was fixed on the surface of the agar, to prepare an Escherichia coli-coated agar medium.

(Chemicals used) As fatty acid dimethylamide represented by the general formula (1), BSC 8000 (hereinafter referred to as "FADMA") manufactured by Bachman Laboratories was used. This contains unsaturated fatty acid dimethylamide represented by the chemical formula (2), and particularly contains a large amount of unsaturated fatty acid dimethylamide having 17 carbon atoms of R such as oleic acid dimethylamide.

[0036]

Embedded image RCO—N (CH ₃ ) ₂ (1) wherein R is an alkenyl group having 5 to 23 carbon atoms.

Glutaraldehyde (hereinafter also referred to as "GA") (50% glutaraldehyde solution (manufactured by Kishida Chemical Co., Ltd.)) and "CMI" (5-chloro- 10.1 wt% of 2-methyl-4-isothiazolin-3-one, 2-methyl-
3.8-isothiazolin-3-one. A drug containing wt%: NS-500W manufactured by Nagase Kasei Kogyo Co., Ltd.) was used.

(BCYEα Plate Medium) The BCYEα plate medium used for the culture of the genus Legionella had the composition shown in Table 1.

[0039]

[Table 1]

<Confirmation of effect on amoebic vegetative body: Example 1> Acanthamoeba 96 ( Acanthamo) cultured for 2 days using the agar medium coated with E. coli prepared as described above.
Eba 96) nutrients were added to sterilized tap water at 1.1 × 10 ⁴ per mL and used as test water.

10 mL of this test water was placed in a tissue culture flask, and after adding the chemicals shown in Table 2, the mixture was allowed to stand at 28 ° C. One hour and three hours after the addition of chemicals, a portion of the test water was collected, serially diluted if necessary, and 1 mL of the test water was applied to an agar medium coated with Escherichia coli, cultured at 28 ° C for 7 days, and then generated on the medium. By counting the number of plaques
The number of surviving amoeba was examined. Table 2 shows the results.

[0042]

[Table 2]

According to Table 2, according to the method for controlling amoeba in an aqueous system using the amoebicide according to the present invention, it is possible to suppress the amoeba vegetative body rapidly even at a very low concentration. You can see that.

<Confirmation of effect on amoeba cysts: Example 2> Acanthamoeba 96 ( Aca) , which was pre-cultured for 7 days using the agar medium coated with Escherichia coli prepared as described above and turned into cysts, was prepared.
ntamoeba 96) was added to sterilized tap water at a concentration of 1.2 × 10 ⁴ per mL, and used as test water.

10 mL of this test water was placed in a tissue culture flask, and after adding the chemicals shown in Table 3, it was allowed to stand at 28 ° C. One hour and three hours after the addition of chemicals, a portion of the test water was collected, serially diluted if necessary, and 1 mL of the test water was applied to an agar medium coated with Escherichia coli, cultured at 28 ° C for 7 days, and then generated on the medium. By counting the number of plaques
The number of surviving amoeba was examined. Table 3 shows the results.

[0046]

[Table 3]

According to Table 3, according to the method for controlling amoeba in an aqueous system using the amoeba-killing agent according to the present invention, it is possible to quickly suppress amoeba cysts at a low concentration even for amoeba cysts. I understand. Glutaraldehyde was effective to some extent against amoeba in a vegetative state, but a slight killing effect was observed on amoeba cysts at an added concentration of 100 mg / mL, but the effect was not sufficient. It turns out that almost no killing effect is obtained.

<Confirmation of effect on Legionella spp .: Example 3> Legionella pneumophila GIFU9134 was placed on a BCYEα plate medium having the composition shown in Table 1.
( Legionella pneumophila G
IFU 9134) and inoculated at 36 ° C. for 2 days. The test water was prepared by adding 5.0 × 10 ⁶ cells per mL to a pH 7.0 phosphate buffer solution. 30 mL of this test water was placed in a 50 mL shake flask, and after adding the chemicals shown in Table 4, the mixture was shaken at 30 ° C. and 120 rpm.
One hour and three hours after the addition of the chemical, a part of the test water was collected, and if necessary, serially diluted.
After spreading on a CYEα plate medium and culturing at 36 ° C. for 5 days, by counting the number of colonies generated on the medium,
The number of surviving Legionella bacteria was examined. Table 4 shows the results.

[0049]

[Table 4]

According to Table 4, according to the method for removing Legionella bacteria using the Legionella bacteria removing agent according to the present invention,
It can be seen that Legionella spp. Can be rapidly eliminated at a low concentration.

<Effect confirmation in water system in which Legionella spp. And amoeba coexist: Example 4> The effect of the present invention was confirmed in an actual cooling water system of an air-conditioning facility in which Legionella spp. And amoeba coexist. went.

The unsaturated fatty acid dimethylamide represented by the chemical formula (2) was added to the circulating cooling water system (refrigeration capacity: 3 refrigeration tons, water holding amount: 100 L, 8 hours a day) of the air conditioning facility twice at weekly intervals. Was added in an amount of 10 g each so that the addition concentration became 100 mg / L ("FADM" in FIG. 1).
A).

At that time, the surviving numbers of Legionella spp. And amoeba in the water system from two weeks before the first addition to four weeks after the second addition were examined. Figure 1 shows the results
Shown in

According to FIG. 1, in the method for removing Legionella spp. In an aqueous system according to the present invention, the fatty acid dimethylamide represented by the general formula (1) was replaced with an amoeba number of 100 m in the aqueous system.
It can be seen that Legionella spp. Can be removed from the aqueous system by adding the L-cell to a concentration of less than 10 per L.

Although dark green algae were growing in the lower tank of the cooling tower in the present water system, one week after the second addition, the algae were completely killed and separated, and the lower tank was clean. Had become.

[0056]

The amoebicide of the present invention itself is a pathogenic agent, and is effective at a low concentration at a low concentration on amoeba which is a host of Legionella sp. It is an excellent amoeba killer that can be controlled.

The method for disinfecting Legionella spp. In an aqueous system according to the present invention is an excellent method for disinfecting Legionella spp. In an aqueous system that is effective at a low concentration even in the presence of amoeba, which is difficult with conventional disinfection methods. Is the way.

[Brief description of the drawings]

FIG. 1 is a diagram showing the effect of the present invention in an actual cooling water system.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 1/50 532 C02F 1/50 532D 540 540C // F28G 13/00 F28G 13/00 A (72) Invention Person Miki Kurihara 4-4 Midorigahara, Tsukuba-shi, Ibaraki Aquas Co., Ltd. Tsukuba Research Laboratory F-term (reference) 4H011 AA02 AD01 BB06 DD01

Claims (6)

[Claims] An amoebicide comprising a dimethyl amide of a fatty acid represented by the general formula (1). Embedded image RCO—N (CH ₃ ) ₂ (1) wherein R is a chain hydrocarbon group having 5 to 23 carbon atoms. 2. In the water system in which the amoeba is alive,
A method for suppressing amoeba in an aqueous system, comprising adding dimethyl amide of a fatty acid represented by the general formula (1). Embedded image RCO—N (CH ₃ ) ₂ (1) wherein R is a chain hydrocarbon group having 5 to 23 carbon atoms. 3. A disinfectant for Legionella spp., Comprising dimethylamide of a fatty acid represented by the general formula (1). Embedded image RCO—N (CH ₃ ) ₂ (1) wherein R is a chain hydrocarbon group having 5 to 23 carbon atoms. 4. A method for removing bacteria of the genus Legionella in an aqueous system, comprising adding dimethylamide of a fatty acid represented by the general formula (1) to an aqueous system in which the genus Legionella is alive. RCO-N (CH ₃ ) ₂ (1) wherein R is a chain hydrocarbon group having 5 to 23 carbon atoms. 5. An agent capable of killing both amoebic vegetative bodies and amoeba cysts in an aqueous system in which Legionella spp. And amoeba coexist, wherein the number of amoeba in the aqueous system is 100 m.
A method for disinfecting Legionella spp. In an aqueous system, the method comprising removing Legionella spp. By adding so that the concentration becomes less than 10 per L. 6. The eradication of Legionella bacteria in an aqueous system, wherein the agent capable of killing both the amoeba vegetative body and the amoeba cyst is dimethylamide of a fatty acid represented by the general formula (1). Method. Embedded image RCO—N (CH ₃ ) ₂ (1) wherein R is a chain hydrocarbon group having 5 to 23 carbon atoms.