Water quality improver for aquaculture as well as preparation method and application of water quality improver

Abstract

The invention relates to the technical field of aquaculture environment regulation and control, in particular to a water quality improver for aquaculture and a preparation method and application thereof. The water quality improver provided by the invention is compounded from yeast beta-glucan and bacillus, is suitable for fresh water and marine culture water bodies, and can realize double effects of water quality improvement and disease prevention and control in high-density culture water bodies with serious organic pollution.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aquaculture environment regulation, and particularly relates to a water quality improver for aquaculture and a preparation method and application thereof. BACKGROUND

[0002] A large amount of waste such as residual feed, feces and dead aquatic organisms is generated in the process of aquaculture, which is an important cause of environmental pollution and water quality deterioration in aquaculture. Specifically, (1) metabolic pollution in aquaculture is the main pollution source. After aquatic organisms ingest feed, metabolic substances are discharged into the water, significantly increasing the total amount of water pollutants; the decomposition of metabolites in water further deteriorates the water environment. (2) Aquatic organisms are deposited in water, and these substances deposited at the bottom of the water can be dissolved again, causing a decrease in water purification capacity and harm to the cultured objects in the water. (3) The use of inputs in aquaculture, especially excessive use of fertilizers, feed and various chemicals, will pollute the water environment.

[0003] The core contradiction of high-density aquaculture is to carry a very high biological load in a limited water body, and its metabolic products and residual feed will quickly pollute the water quality, causing stress, disease and even death of the cultured animals. Therefore, water quality management is the lifeline of the success of high-density aquaculture. Water quality treatment in modern high-density aquaculture has developed into a systematic engineering technology, commonly known as a recirculating aquaculture system, whose core idea is to continuously purify, treat and recycle the water in the culture water body, with only a small amount of new water being added.

[0004] The current recirculation technology for water quality treatment in aquaculture includes: (1) solid-liquid separation technology: mainly including mechanical filtration, foam separator, sedimentation and other specific technologies, the purpose of treatment is to remove suspended particulate matter such as residual feed, feces, organic debris, etc. in the water. (2) Biological treatment technology: mainly including biological filtration technology, constructed wetland method, immobilized microbial technology, etc. Immobilized microbial technology can fix microorganisms on carriers, allowing them to rapidly reproduce in a suitable environment, ensuring their high stability and adaptability. In aquaculture wastewater treatment, immobilized microbial technology can enhance the stability of the environment, thereby improving the efficiency of purifying water quality and preventing the growth of other harmful microorganisms. In addition, immobilized microbial technology can also use natural polymer gel carriers, which means that immobilized microbial technology has a cost advantage, can reduce capital investment to some extent, improve the efficiency of purifying water resources, and is also conducive to the establishment of a recycling system. (3) Specific water quality regulation technology: using oxygenation technology, ozone purification technology, pH regulation technology, ultraviolet disinfection technology and other technologies to improve water quality.

[0005] In addition to the circulating water treatment system, water quality improver is a crucial means and method in high-density aquaculture. Water quality improvers are diverse, and can be mainly divided into the following categories according to their functions: 1. Substrate improver Substrate improver is mainly aimed at the problems of organic matter accumulation, blackening and odor on the bottom of the pond. Substrate improver mainly includes: (1) oxygen-increasing substrate improver, the main components of which are potassium hydrogen peroxymonosulfate composite salt, calcium peroxide and sodium percarbonate (2Na2CO3·3H2O2), the principle of which is to release oxygen and active oxygen when encountering water, oxidize and decompose harmful substances such as hydrogen sulfide and nitrite on the bottom of the pond, kill anaerobic harmful bacteria in the bottom layer, and improve the anoxic state of the bottom mud. (2) Decomposition type substrate improver, the main components of which are composite bacillus, nitrifying bacteria and yeast bacteria, etc. The principle is to directly decompose organic pollutants such as leftover feed and feces on the bottom of the pond through microorganisms, and convert them into harmless substances, thereby reducing the oxygen consumption source from the root.

[0006] 2. Water quality detoxifier Water quality detoxifier is used to quickly degrade or adsorb specific toxic substances in water. Ammonia-nitrite detoxifier such as zeolite powder, bentonite and activated carbon has a rapid but not complete effect through physical adsorption, and is an emergency measure. Sodium thiosulfate (Na2S2O3·5H2O) is commonly used to remove residual chlorine and complex heavy metals, and has a certain alleviating effect on nitrite through oxidation-reduction reaction. Sodium chloride reduces the toxicity of nitrite to fish gills by ion competition, which is one of the most economical and effective methods for freshwater fish to cope with nitrite poisoning. The main components of heavy metal detoxifier include organic acids (such as citric acid and humic acid sodium), EDTA and sodium thiosulfate, which can wrap free heavy metal ions (such as copper, zinc and lead) in water through chelation, reducing their biological toxicity and effectiveness. The main components of algae toxin / disinfectant detoxifier are organic acids, vitamin C and potassium hydrogen peroxymonosulfate, which can destroy the structure of algae toxins through oxidation or complexation, or degrade the toxicity of residual disinfectants.

[0007] 3. Microecological preparation By supplementing beneficial bacteria to establish dominant bacteria, pathogenic bacteria are inhibited competitively, and pollutants are continuously decomposed. Bacillus ( Bacillus ) is the most widely used bacteria, which can secrete potent enzymes to decompose macromolecular organic matter such as proteins, starches and fats, purify water quality and inhibit harmful bacteria such as Vibrio. Oxygenation must be used because of its high oxygen consumption. Photosynthetic bacteria can utilize small molecular organic matter and harmful substances such as hydrogen sulfide in water for photosynthesis, achieving good water purification effect, and are also high-quality feed, but their ability to decompose macromolecular organic matter is weak. Lactic acid bacteria ( Lactobacillus) is a facultative anaerobe that can decompose organic matter, produce lactic acid, reduce pH value, and significantly inhibit gram-negative pathogenic bacteria (such as Vibrio), and is commonly used for internal administration to improve intestinal health. EM bacteria ( Effective Microorganisms ) generally include a symbiotic system of photosynthetic bacteria, lactic acid bacteria, yeast, and other beneficial microorganisms, and have comprehensive functions. Nitrifying bacteria ( Nitrifying bacteria ) are specifically used to build and maintain the core function of the biological filter. The role of splashing nitrifying bacteria is controversial because it needs to attach to the surface to work efficiently.

[0008] The above water quality improvers are more, but most of them have single regulation function, and the pollution components in aquaculture water bodies are complex, so it is necessary to provide a more simple and efficient multifunctional water quality regulation scheme. SUMMARY

[0009] Therefore, it is necessary to provide a water quality improver for aquaculture and a preparation method and application thereof. The present application utilizes yeast beta-glucan and Bacillus to realize the dual functions of "water quality improvement + disease prevention and control", and is simple and efficient in treating water environmental pollution and water quality deterioration in intensive high-density aquaculture.

[0010] The present application adopts the following technical solutions: The present application provides a water quality improver for aquaculture, which is mainly composed of yeast beta-glucan and Bacillus, the yeast beta-glucan is prepared by yeast metabolite extraction, and the Bacillus is selected from Bacillus subtilis and Bacillus licheniformis.

[0011] In some embodiments, the preparation of the yeast beta-glucan includes the steps of pretreatment, high-pressure hot water extraction, and alcohol precipitation of target polysaccharides.

[0012] Preferably, the total number of viable Bacillus is ≥2×10 9 CFU / g, and the mass ratio of the yeast beta-glucan to the Bacillus is (3-5):(8-15).

[0013] Preferably, the water quality improver further comprises bentonite and / or trehalose.

[0014] Preferably, the mass ratio of the yeast beta-glucan, the Bacillus, the bentonite, and the trehalose is (3-5):(8-15):(2-7):(2-4).

[0015] The present application provides a preparation method of a water quality improver for aquaculture, which comprises the following steps: preparing yeast beta-glucan by yeast metabolite extraction; mixing and culturing Bacillus subtilis and Bacillus licheniformis to obtain a Bacillus inoculant; and mixing the yeast beta-glucan and the Bacillus inoculant to obtain the water quality improver.

[0016] The application provides application of a water quality improver for aquaculture in a freshwater aquaculture water body or a seawater aquaculture water body.

[0017] Preferably, in a water body with a water depth of 2 m, the water quality improver is added in an amount of 100-400 g / mu; in a water body with a water depth exceeding 2 m, the amount is increased in proportion to the volume of the water body.

[0018] Preferably, the water quality improver is activated by red sugar water aeration before use, and is sprinkled in the whole pool after dilution.

[0019] Preferably, the water quality improver is used once every 7-10 days, and is prohibited from being used in rainy and hot weather.

[0020] Compared with the prior art, the core technical advantages and beneficial effects of the application are as follows: The application is directed to the water environmental pollution and water quality deterioration of intensive high-density aquaculture water bodies, and by compounding yeast beta-glucan and bacillus, the beta-glucan is used to effectively promote the rapid colonization of bacillus, and at the same time, the immune stimulator effect of yeast beta-glucan is used to activate the non-specific immunity of the cultured animals, so that the dual effects of 'water quality improvement + disease prevention and control' are realized, and the treatment method is simple and efficient. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a preparation process schematic diagram of yeast beta-glucan.

[0022] Figure 2 It is a phytoplankton cell density statistical graph (a) and a zooplankton density statistical graph (b) in Example 4. DETAILED DESCRIPTION

[0023] The application will be further described in detail below in combination with specific examples, so that those skilled in the art can more clearly understand the application. The following examples are only used to illustrate the application, but not to limit the scope of the application. Based on the specific examples in the application, all other examples obtained by those skilled in the art without creative labor are within the protection scope of the application. In the examples of the application, all raw material components are commercially available products well known to those skilled in the art, unless otherwise specified; in the examples of the application, the technical means used are conventional means well known to those skilled in the art, unless otherwise specified.

[0024] Key material source description: Yeast metabolites: purchased from Angel Group.

[0025] Yeast β-glucan: extracted from yeast metabolites, which are first treated with 80% ethanol to remove endogenous enzymes and small molecule free sugars, proteins and non-polar compounds; under a pressure of 150-400 MPa, the target polysaccharide is extracted with hot water at 100 ℃ for 1.5-3 h, precipitated with 80% ethanol, centrifuged, and vacuum dried.

[0026] Example 1 Reference Figure 1 The present embodiment provides a preparation method of yeast β-glucan, comprising the following steps: S1, pretreatment The yeast metabolites are pretreated with 80% ethanol, 25-50 L of 80% ethanol is used per 100 kg of yeast metabolites, and after stirring and mixing uniformly, the mixture is soaked for 24 h. The purpose of this pretreatment is mainly to remove part of the endogenous enzymes and small molecule free sugars, proteins and non-polar compounds in the yeast metabolites, so as to ensure the yield of the target product.

[0027] S2, high-pressure hot water extraction The pretreated yeast metabolites are placed in a high-pressure reaction kettle, and the yeast metabolites are mixed with pure water at a mass ratio of 3:1. Under a pressure of 200 MPa, the mixture is heated to 100 ℃ for 2.5 h to obtain a target polysaccharide extract.

[0028] S3, precipitation method for purifying target product 80% ethanol is mixed with the target polysaccharide extract at a mass ratio of 1:4, the precipitated product is centrifuged and separated, vacuum freeze-dried, packaged, and the yeast β-glucan product is obtained.

[0029] International recognized accurate quantitative method is used for identification: specific β-1,3-glucan endoglucanase is used to degrade β-glucan into oligosaccharides or glucose, and then the hydrolysis product is quantitatively detected by HPLC. The purity of the product is ≥85%, and the content of β-glucan is 2.5 g / kg.

[0030] Example 2 The present embodiment provides a Bacillus mixed bacterial agent, and the preparation method comprises the following steps: mixing Bacillus subtilis and Bacillus licheniformis mixed strains separated and purified from aquaculture tail water at a ratio of 1:1, inoculating into a fermentation tank for fermentation, and the total number of viable bacteria is ≥2×10 9 CFU / g, centrifuging to collect spores, and vacuum drying to obtain the product.

[0031] Example 3 The embodiment provides a water quality improver, and a preparation method thereof comprises the following steps: mixing yeast beta-glucan prepared by the preparation method in embodiment 1, bacillus mixed bacterial agent prepared by the preparation method in embodiment 2, bentonite and trehalose according to the mass percentage of 15%, 50%, 25% and 10%, and packaging, and the water quality improver is obtained.

[0032] Application case: The density of the prawn is 20,000-50,000 per mu, and the feeding amount of the prawn is 3% of the body weight.

[0033] The water quality improver in the embodiment is added, and the dosage is 150 g / mu. Before use, the water quality improver is activated by aeration with brown sugar water for 24 hours, diluted 10 times with pond water, and then poured into the whole pond; the water quality improver is used once every 7-10 days.

[0034] Monitoring results: (1) After 72 hours, the ammonia nitrogen is reduced to 0.9 mg / L.

[0035] (2) After 20 days, it is found that the colonization biomass of bacillus in the intestinal tract of prawn is increased by 10 times, and the feed conversion rate is increased by 12%.

[0036] Embodiment 4 The embodiment provides a water quality improver, and a preparation method thereof comprises the following steps: mixing yeast beta-glucan prepared by the preparation method in embodiment 1, bacillus mixed bacterial agent prepared by the preparation method in embodiment 2, and commercially available bentonite and trehalose according to the mass percentage of 15%, 60%, 15% and 10%, and packaging, and the water quality improver is obtained.

[0037] Application case: The grass carp intensive pond in Honghu City has an area of about 4000 m 2 , and the average water depth is 3.0 m. Each pond is equipped with one bait feeding machine and two oxygenators with a power of 1.5 kW. The stocking density is 15,000 two-year-old grass carps, 1000 white carps and 1000 flower carps. An experimental group (EG) to which yeast metabolites are added and a control group (CG) to which yeast metabolites are not added are set, and each group comprises three parallel ponds.

[0038] The water quality improver in the embodiment is added to the experimental group, and the dosage is 150 g / mu. Before use, the water quality improver is activated by aeration with brown sugar water for 24 hours, diluted 10 times with pond water, and then poured into the whole pond; the water quality improver is used once every 7-10 days.

[0039] The monitoring results of the control group and the experimental group are shown in Figure 2 and Table 1 below: Table 1 Alpha diversity index of plankton Note: same index different group shoulder mark different, lowercase letters represent significant difference P <0.05), capital letters represent extremely significant difference P <0.01), same letter or no letter represents no significant difference P >0.05).

[0040] The results show that: (1) The cell density of phytoplankton, the content of chlorophyll a (Chl a), the density and biomass of zooplankton in the experimental group (EG) were significantly higher than those in the control group (P<0.05).

[0041] (2) The species dominance of cryptophytes and chlorophytes in the phytoplankton community in the experimental group (EG) was significantly improved, and the alpha diversity was higher than that in the control group from the ninth day (P<0.05).

[0042] (3) The species dominance of multiple species of rotifers and cladocerans in the zooplankton community was significantly improved, and the alpha diversity was higher than that in the control group from the twelfth day (P<0.05).

[0043] Example 5 The preparation method of the water quality improver provided in this embodiment comprises: mixing the yeast β-glucan prepared in Example 1, the Bacillus mixed inoculant prepared in Example 2, and commercially available bentonite and trehalose according to the mass percentages of 10%, 50%, 20%, and 20%, and packaging to obtain the water quality improver.

[0044] Application case: In a 45-mu pond in Jiangling County, Huabaizhen was bred, and the fish seed size was 1.8-2 jin / tail, the density was 1000 tails / mu, and 600 jin of compound feed was fed every day.

[0045] The water quality improver of this embodiment is added, and the dosage is 150 g / mu. Before use, it is activated by red sugar water aeration for 24 h, diluted 10 times with pond water, and then poured into the whole pond; it is used once every 7-10 days.

[0046] Monitoring results: (1) The water color of the 45-mu breeding water body was tender yellow green, the pH value was 7.56, the TN and COD Mn were 2.21 mg / L and 11.60 mg / L, respectively, and the phosphate content was 0.133 mg / L.

[0047] (2) The main algal dominant species were Chlorella vulgaris and Cyclotella; the breeding water body environment was in good condition.

[0048] Example 6 The embodiment provides a water quality improver containing only yeast beta-glucan and the bacillus mixed bacterial agent prepared in Example 2, and a preparation method thereof, which comprises the following steps: mixing yeast beta-glucan prepared in Example 1 and the bacillus mixed bacterial agent prepared in Example 2 according to a mass percentage of 25% and 75%, and packaging, to obtain the water quality improver.

[0049] Application case: In 10 mu of ponds in Jiangling County, spotted catfish is mainly bred, and a small amount of turtle is bred. The size of the spotted catfish is 80-100 g per tail, and the amount of the spotted catfish is 4400-5200 tails. Chicken liver and duck liver are fed in the ponds twice a day, and the total amount of the chicken liver and duck liver is 1000-1100 catties.

[0050] The water quality improver is added in an amount of 150 g per mu. Before use, the water quality improver is activated by red sugar water aeration for 24 hours, and then diluted 10 times with pond water, and then sprayed in the pond. The water quality improver is used once every 7-10 days.

[0051] Monitoring results: (1) The water color of the breeding water body is tender yellow green, the pH value is 7.31, the total phosphorus and the permanganate index are 0.093 mg / L and 4.68 mg / L respectively, the orthophosphate content is 0.064 mg / L, the total nitrate nitrogen content is 1.67 mg / L, and the ammonia nitrogen content is 0.15 mg / L.

[0052] (2) The main algae dominant species are chlorella, chlamydomonas and small ring algae; the breeding water body environment is in good condition.

[0053] It is worth emphasizing that the team of inventors found through a large number of experiments that: (1) The compounding ratio of yeast beta-glucan and bacillus mixed bacterial agent (total number of living bacteria is greater than or equal to 2*10 9 CFU / g) in the water quality improver for aquaculture has obvious influence on the water body improvement effect, which is specifically manifested in the aspects of water color, water quality indexes and feeding metabolism of the breeding object; the yeast beta-glucan directly affects the feeding and activity of the breeding object, and then affects the accumulation amount of leftover feed and feces in the water body; the bacillus mixed bacterial agent not only affects the feeding of the breeding object, but also directly affects the water quality improvement. The mass ratio of yeast beta-glucan and bacillus mixed bacterial agent is preferably (3-5):(8-15).

[0054] (2) The content change of bentonite and trehalose in the water quality improver for aquaculture does not have significant influence on the water body improvement. Preferably, the mass ratio of yeast beta-glucan, bacillus, bentonite and trehalose is (3-5):(8-15):(2-7):(2-4).

[0055] It is necessary to point out here that the above embodiments are only for further illustrating and describing the technical solutions of the present application, and are not for further limiting the technical solutions of the present application. The method of the present application is only a preferred embodiment, and is not used for limiting the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A water quality improver for aquaculture, characterized in that, The water quality improver is mainly composed of yeast β-glucan and Bacillus. The yeast β-glucan is prepared by extraction of yeast metabolites, and the Bacillus is selected from Bacillus subtilis and Bacillus licheniformis.

2. The aquaculture water quality improver according to claim 1, characterized in that, The preparation process of the yeast β-glucan includes the steps of pretreatment, high-pressure hot water extraction, and alcohol precipitation of the target polysaccharide.

3. The aquaculture water quality improver according to claim 1 or 2, characterized in that, The total viable count of the Bacillus is ≥2×10⁻⁶. 9 CFU / g, wherein the mass ratio of yeast β-glucan to Bacillus is (3-5):(8-15).

4. The aquaculture water quality improver according to claim 1 or 2, characterized in that, The water quality improver also includes bentonite and / or trehalose.

5. The aquaculture water quality improver according to claim 4, characterized in that, The mass ratio of yeast β-glucan, Bacillus, bentonite, and trehalose is (3-5):(8-15):(2-7):(2-4).

6. The method for preparing the aquaculture water quality improver according to any one of claims 1 to 5, characterized in that, Includes the following steps: Yeast β-glucan was prepared by extraction from yeast metabolites; Bacillus subtilis and Bacillus licheniformis were mixed and cultured to obtain Bacillus inoculum; The product is obtained by mixing yeast β-glucan and Bacillus inoculum.

7. The application of the aquaculture water quality improver according to any one of claims 1 to 5 in freshwater or marine aquaculture water bodies.

8. The application according to claim 7, characterized in that, For water bodies with a depth of 2 m, the dosage of water quality improver is 100-400 g / mu; for water bodies with a depth of more than 2 m, the dosage should be increased proportionally according to the water volume.

9. The application according to claim 7 or 8, characterized in that, The water quality improver is activated by aeration with brown sugar water before use, and then diluted and sprinkled throughout the pond.

10. The application according to claim 9, characterized in that, The water quality improver should be used once every 7 to 10 days.

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