JPH05221874A - Controlling agent for disease of fishes - Google Patents

Abstract

PURPOSE:To obtain the subject controlling agent, comprising nisin as an active ingredient, excellent in safety and economical efficiency and useful for preventing and treating streptococcal infection of a young yellowtail, vibriosis of a sea bream, etc. CONSTITUTION:The objective controlling agent comprises a peptidic antimicrobial substance nisin as an active ingredient. Furthermore, the concentration of this controlling agent is preferably 1-100mug/ml in an agent or a culture pond or a vessel and preferably 0.001-0.01wt.% nisin is added to a feed for culturing fishes.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a fish disease control agent, and more particularly to a fish disease control agent containing the peptide antibacterial substance nisin as an active ingredient.

[0002]

2. Description of the Related Art In recent years, aquaculture has become more and more popular due to a problem of 200 nautical miles and lack of fishery resources due to overfishing and overfishing. Accordingly, high density breeding of fish has been promoted. In particular, in high-density aquaculture fisheries such as hamachi and eel, the frequency of outbreaks of infectious diseases of fish is high, and if left unattended, it may cause near-annihilation damage.
Even if the fish are not completely wiped out, the surviving fish are often damaged, resulting in a significant decrease in commercial value, which is a major obstacle to management.

As a method for preventing and treating infectious diseases of fishes, for example, administration of kasugamycin for Hamachi vibrio disease and nodular disease (JP-A-61-275219) and administration of bile acids for streptococcal infections (JP-A-62) -5921
4), administration of thianphenicols for Vibrio's disease and ulcers (JP-A-48-56812) and the like are known.

However, since most of the above-mentioned methods for preventing diseases are large-scale administration of antibiotics and nutrients,
Effects on fish organisms (toxicity and side effects) There are many problems such as safety to humans, emergence of resistant bacteria, eutrophication of breeding water, and economics of antibiotics and nutrients themselves.
It is desired to develop a simple and effective alternative method.

On the other hand, the peptidic antibacterial substance nisin is a highly safe substance approved by the US FDA as a food additive (Federal Register / v).
ol. 53, no. 66 / Wednesday, Apr
il 6,1988 / page 11247-11251
), Dairy preservatives, lactic acid bacteria contamination prevention during alcoholic beverage brewing, etc. (US Pat.
2, No. 4,584,199, European Patent 18649
(See No. 8). However, nothing is known about the use of Nansin as a disease control agent for fish.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have conducted earnest research on a simpler and more effective method for preventing fish diseases. As a result, they have found that the peptidic antibacterial substance nisin can be an excellent disease control agent for fish, and completed the present invention.

[0007]

Thus, according to the present invention, there is provided a disease control agent for fish, which comprises nisin as an active ingredient. Nisin used in the present invention is Streptococcus lactis ( Strept).
ococcus lactis ) is a peptidic antibacterial substance produced by various strains (Advanc
es in Applied Microbilog
y, vol 27, page 85-123, 1981
(See), Aprin & Barrett (Appline & B
arret Ltd, USA) and the like.
It can also be obtained by culturing Streptococcus lactis capable of producing nisin, and isolating and purifying from a culture by a commonly used method known per se (Journal of General Mi).
crobology, vol 88, page 18
9-192,1975).

The disease controlling agent of the present invention can be used as a preventive and therapeutic agent for bacterial infections of various fishes.
As a method for treating or preventing a bacterial disease of fish using the disease controlling agent of the present invention, the fish is bathed in a liquid mainly containing nisin, or nisin is dissolved in an aquaculture pond or tank to culture the fish. It may be administered, and in some cases, it may be administered by being mixed with the fish feed.

The nisin concentration in the chemical solution or in the culture pond or tank is usually 0.1 to 1000 μg / ml, preferably 1 to 100 μg / ml. The bathing time of the fish in the nisin-containing chemical liquid water is not particularly limited, but usually 1 to
Three hours can be illustrated. In the case of mixed administration with feed, nisin was added to the fish culture feed in an amount of 0.001 to 0.
Add 01 wt% and feed to fish. The addition to the feed is
In the case of a compound feed, it may be carried out at the time of preparing the feed in advance, and when a commercially available fish feed is used, it may be carried out at the time of feeding. The feeding amount can be appropriately selected depending on the fish species, size, etc., and is usually 1.0 to 5.0% of the fish body weight, which may be administered once a day.

When nisin is used as a disease control agent for fish, the active ingredient compound may be used as it is, but usually, it is mixed with various diluents, for example, pellets, powders, particles, granules, tablets and capsules. It can be used in various formulation forms such as, solutions, emulsions and dispersions. The diluent may be solid or liquid, and suitable diluents include, for example, water, ethanol, sucrose, feed oil, starch, talc, bentonite, fish meal, sodium carbonate, sodium hydrogen carbonate and the like. Further, a nutrient, a feed, another antibacterial agent, an insecticide, a metabolic regulator and the like may be added.

[0011]

INDUSTRIAL APPLICABILITY The fish disease control agent of the present invention containing nisin as an active ingredient is used for various bacterial diseases such as Vibrio anguiralum (Vibrio).
vibrio diseases such as yellowtail, Thailand, and flounder caused by Angularuram), streptococcal infections such as salmon, ayu, Thailand, etc. caused by Streptococcus sp., Pasteurella viscida
aeromonas thermonicida (Aer)
It is possible to control pruritus and the like of salmonids caused by Omonas salmonicida.

[0012]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. Example 1 Streptococcus equinus (strand sphere
Antibacterial test against bacteria Streptococcus equinus
ccus equinus) a ATCC12553, sterilized liquid medium (peptone: 5 g, yeast extract: 5 g, _{glucose: 5g, MgSO 4 · 7H 2} O:
1 g, distilled water: 1000 ml, pH 7.0) 10 ml
After culturing at 30 ° C. for 24 hours at 30 ° C. and collecting the bacteria, sterilized artificial seawater (Aquamarine (registered trademark) manufactured by Yashu Pharmaceutical Co., Ltd.)
It was subjected to centrifugal washing twice (6,000 rpm, 10 minutes) with S 40 g dissolved in 1 liter of water) to obtain a test bacterium. Nisin concentration is 0.1 μg / m
1, 1.0 μg / ml, 10.0 μg / ml, 100 μ
The test bacteria were suspended in sterilized artificial seawater dissolved in g / ml at 2 × 10 ⁸ / ml, allowed to stand at 24 ° C. for 3 hours, and then twice with sterilized distilled water. It was washed by centrifugation.
This is appropriately diluted with sterile distilled water, and agar medium (peptone: 5 g, yeast extract: 5 g, glucose: 5 g,
_{MgSO 4 · 7H 2 O: 1g} , agar: 20 g, distilled water:
It was applied to 1000 ml, pH 7), and after culturing at 30 ° C. for 24 hours, the number of surviving bacteria was measured. As a control, the same test was conducted using sterile artificial seawater containing no nisin. The results are shown in Table 1.

[0013]

[Table 1] Table 1 Nisin concentration (μg / ml) Viable cell count (cfu / ml) Survival rate (%) 0 1.9 × 10 ⁸ 95 0.1 1.3 × 10 ⁸ 68 1.0 8.2 × 10 ⁷ 42 10. 0 2.9 × 10 ⁷ 15 100.0 7.5 × 10 ⁶ 4 As is clear from Table 1, the high antibacterial action of nisin against the test bacteria (Streptococcus equinus) was observed.

Example 2 Streptococcus infection of Hamachi
Disease prevention test Two 100 liter aquariums are prepared, each 24 ℃
40 liters of the breeding water of 1 was added, 1 g of nisin was dissolved in one aquarium, and normal breeding water was put in the other aquarium. Eighty yellowtail with an average weight of 0.5 kg 10 ⁸ cf
Streptococcus equinus (Str) at a concentration of u / ml
eptococcus equinus) ATCC12
After 5 hours of bathing in 553 suspension-cultured water for 2 hours, 40 aquatic plants were housed in each aquarium for 10 days, and after 10 days, streptococcal infection (body surface redness, erosion, tumor formation,
The internal bleeding spots, etc.) were observed.

In addition, the disease state was similarly observed by using a water-raised fish containing no nisin as a control. As a result, the number of diseased fish after 10 days of breeding was only 2 in the nisin-containing water-raised fish, whereas it was 39 in the nisin-free water-raised fish. The disease-preventing effect of breeding was recognized.

Example 3 Occurrence of Vibrio disease in Thailand
Inhibition test Two 100 liter water tanks are prepared, each 24 ℃
40 liters of the breeding water of 1 was added, 1 g of nisin was dissolved in one aquarium, and normal breeding water was put in the other aquarium. 80 ties with an average weight of 0.4 kg, 10 ⁸ cfu /
Vibrio anguiralum at a concentration of ml
Anguillarum) ATCC12710 Suspension Breeding After bathing the bacteria for 2 hours in water, 40 algae were stored in both aquariums and bred for 10 days. Vibrio disease onset after 10 days (body surface and mouth tip damage, subcutaneous muscle) And tumor formation in the internal organs) was observed.

Incidentally, the disease state was similarly observed by using a water-raised fish containing no nisin as a control. As a result, the number of diseased fish after the completion of the 10-day breeding was 22 in the nisin-containing water-fed fish, whereas it was 39 in the nisin-free water-fed fish, which was due to the nisin-containing water-fed. The disease-preventing effect was recognized.

Claims (1)

[Claims] 1. A disease control agent for fish, which comprises nisin as an active ingredient.