JPH11671A - Process for removing legionella in water system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for removing effectively bacteria of legionella family, particularly legionella in the state of coexisting with amoeba or the like. SOLUTION: In a process for removing bacteria of legionalla family in a water system, a hinokithiol compound preferably selected out of hinokithiol, its salt, its metal complex and the like is added into a water system in which amoeba and legionella are in the coexistence state, and the loadings are preferably in the range of 1-1000 mg/L, and more preferably in the range of 10-500 mg/L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention eliminates bacteria in a cold / hot water system or a heat storage water system, such as circulating cooling water for a refrigeration system and circulating hot water for a 24-hour bath, in particular, Legionella bacteria, and prevents their growth. On how to do it.

[0002]

2. Description of the Related Art In refrigeration systems used for air conditioning equipment, refrigeration or freezers, circulating water cooled using an open cooling tower or the like is often used in order to efficiently exchange heat. In a 24-hour bath, heated warm water is circulated while passing through a filter. Microorganisms and the like easily enter the circulating water and proliferate, causing heat exchange efficiency of the heat exchanger to be reduced due to slime, causing obstacles such as filter clogging, and pathogenic bacteria, particularly Legionella spp. Proliferation and dispersal cause specific pneumonia, such as Legionnaires' disease and Pontiac fever.

[0003] As a countermeasure against such problems caused by microorganisms, a method of suppressing the growth of bacteria by injecting an antibacterial agent into the circulating water system, a method of mechanically cleaning and cleaning the inside of the apparatus, or a method of cleaning with a cleaning agent. Etc. have been used. And
Various compounds have been proposed as fungicides for controlling Legionella spp., But even those that show a bactericidal effect in a laboratory are not always effective enough when used in an actual operating water system. Was often not obtained.

[0004] By the way, Legionella spp. In the natural world is known to parasitize, proliferate, and coexist even if they are eaten by bacterial predatory protozoa such as amoeba.
However, it was not clear how such a symbiotic relationship between amoeba and the like and Legionella spp. Affects the fungicide resistance of Legionella spp.

On the other hand, it is well known that hinokitiol has an antibacterial activity, and it has been conventionally known that food preservatives (for example, JP-A-59-22467) and preservative additives for cosmetics and pharmaceuticals (for example, No. 5-214364,
JP-A-7-97600, JP-A-7-138155,
JP-A-7-173053, JP-A-8-59419,
JP-A-9-12423, etc., and plant disease preventive agents (for example, JP-A-51-22819, JP-A-64-9010).
No. 2, JP-A-64-90103, JP-A-64-901
No. 04, JP-A-4-182408, etc.) and freshness preservatives for fresh flowers, vegetables, fruits, etc.
And Japanese Patent Application Laid-Open No. Hei 5-221807) have been proposed.

[0006] Antimicrobial agents (for example, see JP-A-3
-77801), an external germicidal disinfectant (for example,
-279271, JP-A-7-53360, JP-A-7-53360
-53369, JP-A-7-69873, etc.), a proposal for use as an antiviral agent (JP-A-8-259439), and a proposal for use as a disinfectant for drainage ports (JP-A-9-239).
No. 20604), but there was no proposal to use it to remove bacteria in water systems.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the fact that there has been no effective means for preventing the growth of Legionella spp. In an aqueous system, particularly in the state of coexistence with amoeba and the like. It is an object of the present invention to provide a method for effectively eliminating Legionella spp. In a water system coexisting with amoeba.

[0008]

The object of the present invention as described above is achieved by a method for removing Legionella spp. From an aqueous system, which comprises adding a hinokitiol compound to the aqueous system. it can. In particular, excellent effects are achieved by a method for removing Legionella spp. From an aqueous system, which comprises adding a hinokitiol compound to an aqueous system coexisting with amoeba and Legionella spp. In the method of the present invention, the amount of the hinokitiol compound is preferably in the range of 1 to 1000 mg / L. Further, the hinokitiol compound is preferably selected from hinokitiol, a salt thereof, and a metal complex thereof.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The method for removing Legionella spp. In an aqueous system according to the present invention comprises the steps of:
000 mg / L, more preferably 10-500 mg / L
L is added so as to be in the range of L, but it is possible to control both these bacteria and protozoa etc. in the case where Legionella sp. Alone exists in such an aqueous system, even when amoeba coexists. It is possible to very effectively remove Legionella spp. From the water system.

As the hinokitiol compound used for the elimination of Legionella bacteria, not only purified hinokitiol, but also unpurified hinokitiol and essential oils such as hinoki oil containing hinokitiol and hiba oil can be used. Also, chemically synthesized hinokitiol (ie,
2-hydroxy-4-isopropyl-2,4,6-cycloheptatrien-1-one) may be used. These hinokitiol compounds may be used alone or in the form of an inclusion compound with, for example, cyclodextrin. Further preferred hinokitiol compounds include salts of hinokitiol such as sodium and potassium, and metal complexes of hinokitiol such as copper, zinc and silver.These metal salts and metal complexes have a suppressed sublimability and are stable. However, it is not only effective but also advantageous in handling.

[0011]

【Example】

(First Example) BCYE having the composition shown in Table 1
On an alpha plate medium, Legionella (Legionella pneumophila)
And cultured at 36 ° C. for 2 days.

[0012]

[Table 1] BCYEα plate medium pure water 1000 mL yeast extract 10.0 g ACES buffer 10.0 g L-cysteine monohydrochloride 0.4 g soluble iron pyrophosphate 0.25 g α-ketoglutaric acid 1.0 g activated carbon powder 1 0.5 g agar 15 g pH 6.9

Next, hinokitiol, a sodium salt of hinokitiol, and a copper complex of hinokitiol were prepared as hinokitiol compounds, and 10.1% of 5-chloro-2-methyl-4-isothiazoline was used as a bactericide for comparison. -3 -one and 3.8% of 2-methyl-4-isothiazolin-3-one (Rohm and
Haas, KATHON WT) and 2-bromo-2-nitropropane-1,3-diol (generic name: bronopol)
Was prepared.

After inoculating the above cultured Legionella in a phosphate buffer at pH 7 to the order of 10 ⁴ cells / mL, a part of the solution is applied to a BCYEα plate medium,
The number of viable bacteria was measured by counting the number of colonies after culturing at 36 ° C. for 5 days. As a result, 2.9 × 10 ⁴ cells /
mL. Next, this liquid was divided and put into each culture flask, and one containing no bactericide and one containing each of the above bactericides at concentrations of 1, 5 and 10 mg / L, respectively, were prepared. After shaking culture for 24 hours, the viable cell count (cells / mL) was measured in the same manner as described above. Table 2 shows the values of the viable cell count after cultivation thus obtained.

[0015]

[Table 2]

From the results shown in Table 2, it can be seen that the hinokitiol compound has excellent bactericidal activity against Legionella.

(Second Example) A culture flask containing a PYGC medium having the composition shown in Table 3 was inoculated with Acanthamoeba and cultured at 30 ° C. for 4 days.
The old medium was discarded, a new PYGC medium was added, and Legionella cultured on a BCYEα plate medium for 2 days was inoculated in the same manner as in Example 1, and cultured at 30 ° C. for 4 days.
Amoeba and Legionella coexist.

When the medium in the culture flask was stirred to remove the amoeba from the wall surface, a part of the culture solution was dropped on a hemocytometer and the number of amoeba was measured under a microscope. It was 10 ⁶ cells / mL. Further, another part of the culture solution was taken out, centrifuged at 10,000 rpm for 20 minutes to destroy the amoeba, applied to a BCYEα plate medium, and counted for the number of colonies after culturing at 36 ° C. for 5 days. , Legionella was 2.6 × 10 ⁶ cells / mL.

[0019]

[Table 3] PYGC medium pure water 950 mL Protease peptone 10.0 g Yeast extract 10.0 g 50% dextrose aqueous solution 20 mL L-cysteine monohydrochloride 0.95 g Sodium chloride 5.0 g 0.5 M hydrogen phosphate 2 Sodium aqueous solution 20 mL 0.5 M potassium dihydrogen phosphate aqueous solution 10 mL 0.4 M magnesium chloride aqueous solution 5 mL 0.4 M calcium chloride aqueous solution 1 mL pH 6.9

A culture flask containing a culture medium in which the amoeba and Legionella coexist was added with the same bactericide as in the first embodiment at a concentration of 10, 30, and 100 mg / L, respectively. An agent-free product was prepared and cultured at 30 ° C. for 7 days. Then, after examining the form of the amoeba by microscopic observation, the culture solution is stirred to uniformly disperse the amoeba and Legionella, and a part of the culture solution is taken out and centrifuged at 10,000 rpm for 20 minutes to remove the amoeba. After disruption, the cells were spread on a BCYEα plate medium and cultured at 36 ° C. for 5 days. The number of colonies was counted to determine the number of viable Legionella cells (cells / mL). The results are shown in Table 4.

On the other hand, another part of the above-mentioned uniformly mixed and dispersed culture solution was directly inoculated into a new PYGC medium and cultured at 30 ° C. for 7 days, and the viable state of amoeba was examined. In addition to the results of the above microscopic observation, Table 4 also shows the state of living as a vegetative body as +, the state of living as a cyst as ±, and the state of dying as −.

[0022]

[Table 4]

From the results shown in Table 4, it can be seen that a conventionally known fungicide having excellent bactericidal activity against Legionella cannot effectively eliminate Legionella in the presence of amoeba, whereas a hinokitiol compound does not effectively dissolve Legionella. However, it has a biocidal power and can effectively remove Legionella coexisting with amoeba. It can be seen that a metal complex of hinokitiol exhibits an excellent effect.

[0024]

According to the present invention, a hinokitiol compound is added to an aqueous system to sterilize Legionella spp. In an aqueous system, and the amoebic bacterium cannot be removed by a conventional fungicide for Legionella spp. There is an effect that Legionella spp. In the coexisting water system can be effectively eliminated.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 1/50 532 C02F 1/50 532L 540 540B A01N 35/06 A01N 35/06

Claims (4)

[Claims] 1. A method for removing Legionella spp. From a water system, comprising adding a hinokitiol compound to the water system. 2. The method according to claim 1, wherein a hinokitiol compound is added to an aqueous system in which amoeba and Legionella coexist. 3. The amount of the hinokitiol compound to be added is 1 to 1.
3. The method according to claim 1, wherein the amount of Legionella is in the range of 000 mg / L. 4. The hinokitiol compound is selected from hinokitiol, a salt thereof, or a metal complex thereof.
The method for removing bacteria of the genus Legionella in an aqueous system according to any one of claims 1 to 3.