JP4469941B2 - Methods and structures for the control of pathogenic microorganisms and organic matter degradation in fish farming - Google Patents

Description

  The present invention relates to a method and a structure for controlling diseases during fish culture or improving the bottom soil environment of aquaculture water area.

  In fish farming, serious damage may occur due to the occurrence of diseases caused by the growth of pathogenic microorganisms or pathogenic viruses. Antibiotics are frequently used for disease control in fish farming. In addition, formalin, malachite green, and the like are provisionally used for the control of fungi that infect eggs and larvae. However, due to the emergence of drug-resistant bacteria and the like, there are situations where the effects of these drugs are reduced. Moreover, since the antibiotics etc. which were added in water are easily spread | diffused by a water flow, an effect becomes temporary. Thus, there is still no effective method capable of controlling epidemics in fish farming, particularly a method that exerts its action effect continuously.

  If pathogenic microorganisms or viruses can be controlled using the antibacterial properties of microorganisms such as bacteria, a more sustained action can be expected as compared with the conventional technique in which antibiotics or the like are added. So far, a technique for suppressing the growth of pathogenic microorganisms or pathogenic viruses by adding Alteromonas bacteria in crustacean culture has been disclosed (see Patent Document 1 and Patent Document 2). However, it has not been confirmed that similar effects are achieved in fish farming. For those skilled in the art, the mechanism of action of pathogenic microorganisms or pathogenic viruses exerting their pathogenicity is completely different between crustaceans and fish, and the above findings in crustaceans are not necessarily applied to fish. I understand what I can't do.

  On the other hand, aquaculture sediments contain sulfur, nitrogen and phosphorus mainly composed of protein feed mainly composed of fish meal or fish dung, where the remaining mixed feed and fish droppings settle and accumulate. It forms sludge made of organic matter, causing toxic gas (hydrogen sulfide, etc.) production and red tide. In addition, these phenomena cause poor growth of fish, infection with pathogenic bacteria or pathogenic viruses, and massive drowning. Therefore, tillage and spraying of terrestrial bacteria such as Bacillus bacteria are performed to improve the bottom soil of the aquaculture area, but the effect is temporary because terrestrial bacteria cannot grow in seawater. Thus, there is still no method that can continuously improve the soil environment of the aquaculture area.

  In order to decompose organic matter such as sludge in the aquaculture water or the aquaculture bottom soil, a method using bacteria living in the water is conceivable. So far, it is known that the genus Alteromonas, which is a marine bacterium, has the ability to degrade polysaccharides (see Patent Document 3), but degrades organic matter derived from proteins that are problematic in aquaculture and fishery. It has not been confirmed whether or not.

JP 05-076351 A Japanese Patent Laid-Open No. 09-206067 Japanese Patent Application Laid-Open No. 08-298937

  The problem to be solved by the present invention is to provide a method for suppressing the growth of pathogenic microorganisms or pathogenic viruses and the method for decomposing organic matter accumulated in the aquaculture water area or the bottom soil of the aquaculture area when fish is cultured. It is.

  The problem to be solved by the present invention is further to provide a structure for simultaneously and continuously suppressing the growth of pathogenic microorganisms and / or pathogenic viruses and decomposing organic matter during fish culture. Is to provide.

That is, the present invention includes the following inventions.
(1) When fish is cultured, pathogenic microorganisms are added by adding bacteria belonging to the genus Alteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to decompose organic matter to the aquaculture water. Alternatively, a method for suppressing the growth of pathogenic virus.
(2) By adding bacteria belonging to the genus Alteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to decompose organic matter to the aquaculture water, or to the bottom soil of the aquaculture water area A method of decomposing accumulated organic matter.
(3) The above-mentioned organic substance is an organic substance containing sulfur, nitrogen and phosphorus mainly composed of a mixed feed mainly composed of fish meal or a protein derived from fish droppings in sludge. the method of.
(4) A fish culture structure carrying bacteria belonging to the genus Alteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to decompose organic matter is added to the aquaculture water. The method according to any one of (1) to (3) above.
(5) A fish culture structure carrying bacteria belonging to the genus Alteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to decompose organic matter.
(6) The fish culture structure according to (5) above, wherein the structure is a fish culture feed, a netting support column, a fishing reef, or small particles.

  The present invention provides a method for suppressing the growth of pathogenic microorganisms or pathogenic viruses during fish farming.

  The present invention provides a method for decomposing organic matter accumulated in aquaculture water area or in the bottom soil of the aquaculture area.

  Furthermore, the present invention provides a structure for simultaneously and continuously carrying out the suppression of the growth of pathogenic microorganisms and / or pathogenic viruses and the decomposition of organic matter during fish farming.

Hereinafter, the present invention will be described in more detail.
In the present invention, firstly, in the cultivation of fish, pathogenicity is achieved by adding bacteria belonging to the genus Arteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to decompose organic matter to the aquaculture water. The present invention relates to a method for suppressing the growth of microorganisms or pathogenic viruses. Since bacteria have the ability to grow themselves, the effect is more sustained as compared to the conventional technique in which antibiotics are added.

  Secondly, the present invention provides a culture water or culture by adding bacteria belonging to the genus Alteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to decompose organic matter to the culture water. The present invention relates to a method for decomposing organic matter accumulated in the bottom soil of a water area.

  In the present invention, “fish” means any fish that is obvious to those skilled in the art. For example, sea fish such as Thailand, yellowtail, flounder, amberjack, striped mackerel, coho salmon, pufferfish, or ayu, rainbow trout, eel, yamame , Freshwater fish such as amago, char, and smelt.

  In the present invention, the term “bacteria belonging to the genus Alteromonas having the ability to inhibit the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to degrade organic matter” refers to inhibiting the growth of pathogenic microorganisms and / or pathogenic viruses. Means any bacterium belonging to the genus Alteromonas, having the ability to degrade organic matter, for example Alteromonas macleodii, Alteromonas haloplanktis, A. espejiana , Alteromonas undina (A. undina), Alteromonas rubra (A. rubra), Alteromonas hanedai (A. vana), etc.

  Among the bacteria belonging to the genus Alteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to degrade organic matter, bacteria that are particularly preferred for use in the present invention have been discovered by the present inventors. It is a bacterium named Alteromonas macreody EKZ-2 strain. This Alteromonas macreody EKZ-2 strain has been deposited at the National Institute of Advanced Industrial Science and Technology Patent Biological Deposit Center under the deposit number FERM P-19541.

  In the present invention, “adding bacteria into culture water” means adding appropriate bacteria directly or in a culture medium with the bacteria supported on the culture water. The form of “addition” may be arbitrary, for example, a form in which a suspension containing bacteria is sprayed or sprayed on the aquaculture water area, or a substance in which the bacteria are supported on a carrier is sprayed, introduced, and installed in the aquaculture water Although the form to do is mentioned, it is not restricted to these. It is preferable to add a fish culture structure carrying bacteria belonging to the genus Alteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to decompose organic matter to the culture water. See the description below for the structure.

  In the present invention, the `` pathogenic microorganism '' is one that changes depending on the target fish, for example, pathogenic bacteria, for example, as pathogenic bacteria Vibrio anguillarum, Eduwaziera, Examples include Tarda (Edwardsiella tarda), Saprolegina diclina, Dermocystidium anguillae, and Candida sake.

  In the present invention, “pathogenic virus” varies depending on the target fish. For example, infectious hematopoietic necrosis virus (IHNV), iridovirus (LCDV), nodavirus (SJNNV), birna Examples include viruses (YAV) and rhabdoviruses (HIRRV).

  In the present invention, `` organic matter accumulated in the aquaculture water area or the bottom soil of the aquaculture area '' means, for example, sludge, animal and plant or animal and plant plankton carcasses, residue of cultured fish feed, fish dung, It means organic substances mainly composed of protein feed mainly composed of fish meal or protein derived from fish droppings. The organic matter may contain sulfur, nitrogen and phosphorus.

  Thirdly, the present invention relates to a fish culture structure that carries bacteria belonging to the genus Alteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to decompose organic matter. The structure is used in the above-described method according to the present invention for suppressing the growth of pathogenic microorganisms or pathogenic viruses during the cultivation of fish, and for decomposing organic matter accumulated in the aquaculture water area or the bottom soil of the aquaculture area. can do.

  The above-mentioned Alteromonas bacteria are carried in the structure, and when the structure is added to the aquaculture water, the Alteromonas bacteria grow in the structure and gradually flow out to cause pathogenicity outside the structure. It suppresses the growth of microorganisms and / or pathogenic viruses, and decomposes organic matter accumulated in the aquaculture water area or the bottom soil of the aquaculture area. When the structure is added in water, the Alteromonas bacterium is supported in the structure, or even if it flows out of the structure, the outflow rate is slow. The effect is lasting. Furthermore, when the Alteromonas bacterium supported in the structure can continue to grow in the structure even after the structure is added to the aquaculture water, advantageous effects of the Alteramonus bacterium Is more preferable because it becomes more sustainable.

  The “structure” in the present invention is a part or all of a part thereof from a part to which bacteria belonging to the genus Alteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to decompose organic substances can adhere. It has become. Since the bacterium has a property of adhering to various materials, the attachable part may be composed of various materials alone or in combination. For example, a feed for cultured fish containing carbohydrates, proteins, lipids, nucleic acids, etc. Constituent materials, natural or synthetic fibers, natural or synthetic resins (eg biodegradable plastics and biodegradable resins), concrete, ceramics, dredged sand, rocks (eg gravel), wood charcoal, wood, etc. It may be made of any material. When biodegradable materials such as biodegradable plastics, biodegradable resins, and wood are used, the adherable part will be decomposed and disappeared in water after a certain period of time. is there. The portion may have a smooth structure (for example, a smooth material surface) or a porous structure, but preferably has a porous structure.

  Examples of the structure in the present invention include cultured fish feed (including capsule feed), fish nets, netting support pillars, fishing reefs, and small particles.

  The structure of the present invention is preferably a feed for cultured fish. In this case, the fish feeds on the useful microorganisms contained in the feed and the pathogenic microorganisms in the digestive tract are exterminated, while the remaining food and feces containing microorganisms settle on the bottom soil and organic matter in the adjacent aquaculture water and sludge Is advantageous in that it is decomposed. The feed for cultured fish carrying bacteria belonging to the genus Alteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to decompose organic matter can be converted to normal cultured fish feed by any method. It can obtain by adding suitably. The feed for cultured fish may be any feed as long as it can be used for fish culture, and examples thereof include blended feed, capsule feed, and live feed obtained by crushing live fish.

  The structure of the present invention is preferably also a net-like support column or reef. A supporting column or fishing reef of net ikesu carrying bacteria belonging to the genus Alteromonas having the ability to suppress the growth of pathogenic microorganisms and / or pathogenic viruses and the ability to decompose organic matter, such as paint, concrete, clay, etc. The mixture can be obtained by smearing or spraying on the support pillar of the net ikesu or the surface of the fishing reef. When there is a concern about the peeling of the clay, the clay mixed with the cells can be more firmly fixed using an adhesive such as a bond. The supporting net or the fishing reef of the net ikesu used here may be arbitrary as long as it can be installed when fish is cultivated. Bacteria are mixed in the paint by mixing in a paint a porous material such as cinnabar sand, activated carbon, clay particles or the like adsorbed with the bacteria. At this time, the paint may be a normal paint. Bacteria are mixed in concrete by mixing the porous material with the bacteria adsorbed therein. Here, the concrete may be normal. Bacteria can be mixed in clay by directly mixing bacterial cultures with clay. Here, the clay may be conventional.

  The structures of the present invention are preferably also small particles. Here, “small particles” mean cinnabar, activated carbon, clay particles, and the like. The method of supporting bacteria on these small particles is as described in the previous paragraph.

  In the present invention, various methods other than those described above can be used to support the genus Alteromonas on the structure. For example, there is a method of culturing the bacteria and transplanting the cultured cells by directly smearing or spraying on the structure in the state of a cell suspension mixed with an arbitrary liquid as necessary.

  In addition, it is preferable that the structure is allowed to stand in seawater or fresh water for 2 to 3 days after transplanting Arteromonas bacteria to the structure, because the bacteria are more firmly supported on the carrier. In order to allow the transplanted bacteria to grow more easily, any method such as applying alcohols, chlorinating agents, etc. to the structure surface or irradiating with ultraviolet rays before transplanting the bacteria It is preferable that the surface of the structure is sterilized and further washed with sterilized water.

  Further, in order to promote the growth of the bacteria belonging to the genus Alteromonas supported on the structure, it is preferable to further support the structure with a nutrient component for bacterial growth. In addition, after transplanting the bacteria, the structure is left on the structure for a certain period of time in a tank containing seawater or fresh water to which nutrients for the growth of bacteria such as amino acids, organic acids and vitamins are added. It is also preferable to proliferate.

Specific examples of the structure of the present invention actually performed by the present inventors include the following. A mixture of commercially available clay and cultured cells of Alteromonas macreody EKZ-2 strain to a final concentration of 10 ⁸ cells / mL was smeared on the support pillars of fishing reefs (concrete blocks) or aquaculture nets. Here, when it was feared that the clay peeled, the clay mixed with the cells was fixed more firmly using an adhesive such as a bond. Subsequently, when the fish reef or aquaculture net IKES was placed in the aquaculture water, the cells were liberated into seawater at a rate of 10 ⁶ cells / mL / day, and organic substances such as sludge were decomposed. In addition, when a fishing reef (concrete block) fixed with a mixture of clay and fungi similar to the above is installed on the undersea soil of aquaculture ikesu, or when dredged sand or activated carbon with the mixture fixed is sprayed, The cells were liberated into seawater at a rate of 10 ⁶ cells / mL / day, and organic substances such as sludge were decomposed. Furthermore, the bacterial cell culture solution of Alteromonas macreody EKZ-2 is adsorbed on a porous material such as cinnabar sand or activated carbon, and the cinnabar sand or activated carbon is mixed with concrete and smeared on the fishing reef. When the cells were installed, the cells were released into seawater at a rate of 10 ⁶ cells / mL / day, and organic substances such as sludge were decomposed. In this case, many of the bacteria belonging to the genus Alteromonas distributed in the small pores in the porous material could survive and proliferate without contacting the concrete. The cell release rate can be measured by the same method as described in Example 5 below.

  In addition, when the present inventors transplanted the above-mentioned Arteromonas bacteria on an adherent substrate (concrete block with a rough surface), even if left in seawater or fresh water, most of the bacteria remained on the substrate due to its adherence characteristics. They also grew on the base using nutrients in water. FIG. 1 shows the results of measuring the occupancy rate of Alteromonas macreody EKZ-2 on the base installed in sea water over time. As shown in FIG. 1, since the occupation rate of the genus Alteromonas remains high even after 30 days, it can be seen that most of the inoculated cells remain on the base.

  See Examples 2, 3, and 4 for examples of adding Alteromonas spp. To cultured fish feed.

Isolation and Identification of Alteromonas McLeody EKZ-2 Strain Alteromonas macreody EKZ-2 strain used in this example is a strain isolated from coastal seawater and has the following characteristics.
A): It is 1 to 3 microns in length, its shape is short gonococcus, and both ends are rounded. A flagellum is generated from the rear edge of the body and moves. The color is yellowish white with transparency.
A): Medium: Peptone medium Composition: Bacto-peptone (Difco Co. Ltd.) 2 g, Bacto-yeast extracts (same as above) 1 g, Iron citrate (same as above) 0.1 g, Seawater 1 L, pH 7.6 To do.

Mycological properties of Alteromonas sp.
1-1. Cell shape: short rod shape, rounded at both ends Cell size: 1-3 (μm). 1-2. Polymorphism: Various cells with different lengths are often present in normal culture. 1-3. Motility: yes, flagella: 1 on the back edge of the body, spores: no, Gram staining: negative, acidity: no.

2-1. Growth degree: A colony of several mm is formed by culturing for 5 days, Color: Light yellowish white, Gloss: None in particular, Surface is smooth, Diffusible dye: None

3-1. Nitrate reduction: Reduced weakly by long-term culture (7 days). 3-2. Denitrification reaction:-. 3-3. MR test:-. 3-4. VP test:-. 3-5. Indole:-. 3-6. Hydrogen sulfide: −. 3-7. Starch hydrolysis:-. 3-8. Citric acid (K): + (C): +. 3-9. Use of nitrate: +, Use of ammonium salt: +. 3-10. Dye formation:-. 3-11. Urease:-. 3-12. Oxidase: +. 3-13. Catalase: +. 3-14. pH: 5.0 (-), 5.6 (+), 8.6 (+), 9.0 (+). 3-15. Temperature: mesophilic 5-25 ° C. Oxygen demand: Aerobic. 3-16. OF test: oxidative. G-C content: 38-50 mol%.

4-1. NaCl concentration and growth: Growth at 0.3-10%, optimal range 0.3-4%.
(1) Nucleic acid extraction
Nucleic acids were extracted using a “Sepa Gene” kit (manufactured by Sanko Junyaku Co., Ltd.) and then recovered by ethanol precipitation.
(2) PCR
Amplification of about 450 bp was performed using two kinds of universal primers specific for 16S rRNA (5 ′ end side and 3 ′ end side).
(3) Purification of PCR amplification product After amplification, purification was performed using a spin column (Pharmacia).
(4) Analysis of 16S rRNA base sequence The purified PCR amplification product was subjected to base sequence analysis of 456 bp on the 5 'end side using Applied Biosystems 377 DNA Sequencer (manufactured by PerkinElmer).
(5) Homologous analysis by 16S rRNA database search Online search was performed from Genebank database.

The base sequence of the genus Alteromonas is shown in FIG.
As a result of investigating the properties of the bacterium according to the description of the new bacterial species in the Industrial Microorganisms Revised Edition (Edited by the Patent Office), and examining its taxonomic position based on Baumann et al. (1984), The strain was identified as Alteromonas macreody.

  The present inventors named this strain Alteromonas macreody EKZ-2 strain, and deposited it with the accession number FERM P-19541 at the National Institute of Advanced Industrial Science and Technology Patent Biological Deposit Center.

Antibacterial test It was confirmed as follows that the above-mentioned Alteromonas macreody EKZ-2 strain has the ability to suppress the growth of pathogenic bacteria.

  Pathogenic bacteria between smears after transplanting Vibrio anguillarum or Edwardsiella tarda, a fish disease-causing bacterium, between two smears of the above strains previously smeared on an agar medium and cultured at 25 ° C for 10 days As shown in Table 1, the growth of Vibrio anguillaram and Edwardsiella tarda was suppressed as compared with the size of the colony when the colony size was cultured using only the pathogenic bacteria as a control. “Inhibition rate” in Table 1 is a percentage of the ratio of the width of the colonies of Vibrio anguillaram (or Edwardsiella tarda) on the control medium to the same size of the colonies of the same bacteria in the test group. It is.

Antiviral test It was confirmed as follows that the above-mentioned strain Alteromonas macreody EKZ-2 strain has the ability to suppress the growth of pathogenic viruses.

  Tests whether the culture supernatant of the above strains suppresses the action of infectious hematopoietic necrosis virus (IHNV), the causative virus of infectious hematopoietic necrosis, in the culture system of chinook salmon cell CHSE-214 did. The inhibitory effect was determined using the degree of inhibition of degeneration effect (CPE) of chinook salmon cells as an index.

Chinook salmon cells CHSE-214 in 1 mL of liquid medium (containing 10% bovine serum component, 0.075% NaHCO ₃ , 100 IU / mL penicillin, 100 μg / mL streptomycin, 1.6% Tris-HCl (pH 7.8)) After culturing at 15 ° C., an IHNV culture solution and the culture supernatant (0.1 mL) of the above genus Alteromonas were added to the culture system. As a control experiment, only IHNV culture solution (0.1 mL) was added to the culture system. Here, the culture supernatant of the above-mentioned bacteria belonging to the genus Alteromonas is cultivated in ZoBell 2216E medium for 3 days at 25 ° C., then centrifuged (4000 rpm) to precipitate the cells, and filtered through a 0.22 μm filter. It refers to the filtrate obtained. The IHNV culture solution refers to a filtrate obtained by growing IHNV using the same culture solution and CHSE-214 and then filtering with a 0.45 μm filter.

  CPE after addition of the above cell culture supernatant was measured over time. A low CPE is considered to mean that virus growth is suppressed. The results are shown in FIG. As shown in FIG. 3, the growth of IHNV was inhibited when the culture supernatant of Alteromonas macreody EKZ-2 strain was added.

Preparation of feed containing Alteromonas macreodye strain EKZ-2
1. Preparation of mixed feed A mixed feed for fish carrying the Alteromonas McLeody EKZ-2 strain was added to a commercially available powdered mixed feed (manufactured by Nihon Suisan Co., Ltd.). Difco) (5 g), yeast extract (Difco) 1 g, iron acetate 0.1 g, seawater 1000 ml of seawater and adjusted to pH 7.6 to obtain a culture medium containing the cells cultured in the same strain 20) It was prepared by adding w / v% and mixing well.

2. Preparation of capsule feed The capsule feed for fish carrying the Alteromonas macreody EKZ-2 strain is a commercially available capsule (manufactured by Sigma) containing 400 mg of mixed feed containing the same strain prepared in the same procedure as above. Prepared by encapsulation.

Viral attack test against Thailand The feed prepared in Example 2 or the feed containing no Alteromonas macreodye EKZ-2 strain (control experiment) was placed in Thailand (approximately 8 cm in length, 20 fish per experimental section) in a volume of 100 L. After administration for 10 days at a rate of 5 g / tail / day at 25 ° C. at a breeding density of 0.2 tail / L in the water tank, an intraperitoneal injection of an iridovirus solution set at a lethal concentration in Thailand was performed. Here, the feed that does not contain the Alteromonas macreody EKZ-2 strain used in the control experiment is a commercially available powdered feed (manufactured by Nihon Suisan Co., Ltd.), 5 g of hepton (manufactured by Difco), 1 g of yeast extract (manufactured by Difco), A liquid medium (excluding strains) obtained by dissolving in 0.1 g of iron acetate and 1000 mL of seawater and adjusting to pH 7.6 was added at a rate of 20 w / v% and mixed well. The above-mentioned iridovirus solution is obtained by previously culturing a virus in the Thai abdominal cavity and diluting the virus solution taken out from the abdominal cavity after the death of Thailand to a lethal concentration. Here, the lethal concentration was determined by confirming the concentration at which a virus solution taken out from the abdominal cavity after death in Thailand was diluted in various proportions to Thailand and actually infected and killed.

  Thereafter, Thailand in both experimental groups were reared with the same feed that did not contain the Alteromonas macreodye EKZ-2 strain used in the control experiment, and the survival rate of the fish in both experimental groups was measured over time. The results are shown in FIG. All of Thailand in the Alteromonas McLeody EKZ-2 strain-free zone was killed, but 80% of the Thailand in the Alteromonas McLeody EKZ-2 strain-survived region survived.

Quantitative determination of nutrient salt in flounder breeding tank bottom sand In a tank filled with sand (100 L capacity), the mixed feed prepared in Example 2 or Alteromonas macreody EKZ-2 strain prepared in the same manner as in Example 3 About 10 cm / m ^{2 at} a density of 10 individuals / m ² at a rate of 5 g / tail / day at 20 ° C. Grown for months, among the nutrients accumulated in the sand, the total sulfide amount, total nitrogen amount, total phosphorus amount and total organic matter amount (loss of burning) were measured.

  The total sulfide amount was measured by the iodometric titration method. The total nitrogen amount was measured by the potassium peroxodisulfate oxidation method. The total phosphorus amount was measured by the ascorbic acid reduction method. The loss on ignition was measured by heating the sample organic matter at 600 ° C. All of these measurements were performed according to standard measurement procedures well known to those skilled in the art.

  The results are shown in FIG. When diet containing Alteromonas macreody EKZ-2 strain was administered to Japanese flounder, total sulfide, total nitrogen, total phosphorus and total organic matter decreased. Thus, it was shown that organic matter decomposition in the bottom soil of the aquaculture area progressed.

Commercially available clay (synthetic vegetable oil clay, manufactured by Nihon Kyoiku Seisakusho Co., Ltd.) and cultured cells of Alteromonas macreody EKZ-2 (cultured in ZoBell 2216E medium to a concentration of about 10 ¹⁰ cells / mL) And the final concentration of 10 ⁸ cells / mL were smeared on the support pillars of the aquaculture net ikesu. When the aquaculture net IKES was placed in a flounder breeding tank (100 L capacity), it was observed that the amount of accumulated flounder feces decreased.

Separately, place the mixture of the clay and bacteria an appropriate amount, to the water tank (10 L capacity), where sterile seawater 5 L was added, and counted the number of bacteria liberated in sea water, 10 ⁶ cells It was revealed that the Alteromonas bacteria of the present invention were released in seawater at a rate of / mL / day. Therefore, it is considered that the bacterium belonging to the genus Alteromonas of the present invention is liberated from the above-mentioned aquaculture net ikesu at the same release rate in the aquaculture water.

It is a figure which shows the occupation rate of Alteromonas macreody in the bacterial group on the adhesion base (concrete block). It is a figure which shows the base sequence of 16SrRNA of Alteromonas macreody. It is a figure which shows that the proliferation of IHNV was suppressed when the culture supernatant of Alteromonas macreody EKZ-2 strain was added. It is a figure which shows the breeding | raising result of Thailand by administration of the compound feed with which antiviral bacterium Alteromonas macreody was added or not added. It is a figure which shows the nutrient salt density | concentration in the sole sand of a flounder breeding tank in the case where the Alteromonas macreody EKZ-2 strain | stump | stock (only "microorganism" in a figure)) is added in a feed, and the case where it does not add.

Claims (8)

A method of suppressing the growth of pathogenic bacteria and pathogenic viruses by adding Alteromonas macreody EKZ-2 strain (Accession No. FERM P-19541) to the aquaculture water during fish culture. A method of decomposing organic matter accumulated in the aquaculture water area or the bottom soil of the aquaculture area by adding Alteromonas macreody EKZ-2 strain (Accession No. FERM P-19541) to the aquaculture water.   The method according to claim 2, wherein the organic substance is an organic substance containing sulfur, nitrogen, and phosphorus mainly composed of a mixed feed mainly composed of fish meal or a protein derived from fish droppings in sludge.   The method according to claim 2 or 3, wherein the organic matter is decomposed and growth of pathogenic bacteria and pathogenic viruses is suppressed. The structure for fish culture formed by supporting Alteromonas macreody EKZ-2 strain (Accession No. FERM P-19541) is added to the aquaculture water according to any one of claims 1 to 4. Method. A fish culture structure carrying Alteromonas macreody EKZ-2 strain (Accession No. FERM P-19541) . The fish culture structure according to claim 6 , wherein the structure is a fish culture feed, a netting support pillar, a fishing reef, or a small particle.   Alteromonas macreody EKZ-2 strain (Accession number FERM P-19541).

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