CN109231494B - Water quality improver for prawn culture and preparation method thereof - Google Patents

Abstract

The invention relates to a water quality modifier for prawn culture and a preparation method thereof. The invention can form an effective and long-term C/N regulation system; inhibiting the propagation of harmful bacteria, forming a large amount of biological floccules and providing a good environment for the growth of prawns.

Description

Water quality improver for prawn culture and preparation method thereof

Technical Field

The invention relates to a water quality improver, in particular to a water quality improver for prawn culture and a preparation method thereof.

Background

With the development of modern industrialized and intensive prawn culture, a high-density culture mode not only ensures that the ecological system of a culture environment has a single structure and weak resistance, but also easily causes water quality deterioration and disease outbreak, and simultaneously, because people also frequently use chemical drugs and antibiotics to prevent and treat prawn diseases, the negative effects caused by long-term large-dose drug use are very obvious: it not only changes the normal composition of prawn intestinal flora, resulting in the imbalance of microecological environment in intestinal tract, but also makes the medicine form residue in organism, and hinders the healthy development of pollution-free aquaculture industry.

In recent years, carbon-nitrogen ratio (C/N) regulation technology has played an increasingly important role in the prawn farming industry. In the culture process, carbon sources in various forms are directly put into the water body, and the propagation of heterotrophic microorganisms can be promoted by adjusting C/N (C/N is more than 10) in the water body, the heterotrophic microorganisms consume inorganic nitrogen in the culture water body as a nitrogen source required by the growth and propagation of the heterotrophic microorganisms, so that the accumulation of toxic inorganic nitrogen compounds such as ammonia nitrogen, nitrite nitrogen and the like in the water body is reduced, and the water quality is effectively stabilized; meanwhile, a microbial protein source is added to protozoa, micro zooplankton and cultured animals, and the healthy growth of the prawns is promoted.

At present, the types of carbon sources put in the existing research and production are mainly sucrose, cassava meal, molasses, brown sugar and other substances, the putting cost is high, and an effective long-term action system cannot be formed, so that the development and development of a carbon source adding water quality modifier which is low in price and can act for a long time is necessary, and the carbon source adding water quality modifier has important significance for promoting the healthy development of prawn culture and reducing the pollution of the culture to water.

Disclosure of Invention

Aiming at the defects, the invention provides the water quality modifier for prawn culture and the preparation method thereof, which can effectively regulate and control the water quality.

The inventor adds the optimized carbon source and the probiotics in the process of prawn culture, and improves the utilization efficiency of the toxic inorganic nitrogen compound by regulating C/N and promoting the growth and the reproduction of bacteria, thereby achieving the purposes of improving water quality and promoting the growth of prawns.

In a first aspect, the water quality improver for prawn culture comprises a carbon source culture medium and a fermentation broth of microbial strains, wherein the carbon source culture medium comprises the following raw materials in parts by weight: 10-15 parts of straw powder, 15-20 parts of rice chaff, 5-10 parts of straw powder, 5-10 parts of multi-mineral premix and 3-5 parts of active substances; the fermentation liquid of the microbial strain is obtained by fermenting the microbial strain in a microbial fermentation culture medium, wherein the microbial strain comprises compound bacillus, the compound bacillus comprises bacillus subtilis, bacillus licheniformis and bacillus coagulans, and the microbial fermentation culture medium comprises the following raw materials in parts by weight: 60-70 parts of straw powder, 20-30 parts of wheat bran, 3-5 parts of peptone, 1-3 parts of beef extract, 3-6 parts of ammonium sulfate, 0.3-0.6 part of monopotassium phosphate and 0.1-0.3 part of magnesium sulfate.

Preferably, the bacillus compositus comprises the following components in parts by weight: 3-6 parts of bacillus subtilis, 2-3 parts of bacillus licheniformis and 1-2 parts of bacillus coagulans.

Further preferably, the microbial fermentation medium comprises the following raw materials in parts by weight: 70 parts of straw powder, 20 parts of wheat bran, 3 parts of peptone, 1 part of beef extract, 4 parts of ammonium sulfate, 0.5 part of monopotassium phosphate and 0.2 part of magnesium sulfate.

Further preferably, the carbon source culture medium comprises the following raw materials in parts by weight: 15 parts of straw powder, 20 parts of rice chaff, 5 parts of straw powder, 5 parts of multi-mineral premix and 3 parts of active substances.

Preferably, the polymineral premix comprises zinc sulfate monohydrate, manganese sulfate monohydrate, and ferrous sulfate.

Further preferably, the polymineral premix comprises, in weight percent: 1-5% of zinc sulfate monohydrate, 1-5% of manganese sulfate monohydrate, 3-8% of ferrous sulfate and 85-95% of rice chaff.

Preferably, the active substance comprises glucanase, CPPS (mineral uptake promoting polypeptide) and biotin.

Further preferably, the active substances comprise, in weight percent: 3-8% of glucanase, 0.5-2% of CPPS, 0.2-1% of biotin and 90-95% of starch.

Preferably, the fermentation liquid of the microbial strains is obtained by fermenting the microbial strains in a microbial fermentation culture medium, concentrating and drying.

Preferably, the fermentation liquor of the dried microbial strains accounts for 5-10% of the total volume of the water quality modifier.

In a second aspect, the preparation method of the water quality modifier for prawn culture comprises the following steps:

(1) and (3) microbial fermentation: inoculating the composite bacillus strain in a microbial fermentation culture medium, wherein the inoculation amount is 4-5% of the total volume of the culture medium, and the inoculation amount is 180-200 r.min at 30-32 DEG C^-1Continuously ventilating and fermenting for 90 hours to obtain fermentation liquor;

(2) and (3) drying: drying the fermentation liquor to obtain dried bacterial powder of the fermentation liquor;

(3) mixing: adding the bacterial powder into a carbon source culture medium in an amount which accounts for 5-10% of the volume of the modifier, and mixing to obtain the water quality modifier.

Preferably, the preparation method of the water quality modifier for prawn culture comprises the following steps:

(1) and (3) microbial fermentation: inoculating the composite bacillus strain into a microbial fermentation culture medium, wherein the inoculation amount is 4-5% of the total volume of the culture medium, and the temperature is 30-32 ℃ and the inoculation amount is 180-200 r.min^-1Continuously ventilating and fermenting for 90 hours at a rotating speed to obtain fermentation liquor;

(2) and (3) drying: filter-pressing the fermentation liquor, ultrafiltering, concentrating, and spray drying to obtain dried powder of the fermentation liquor;

(3) mixing: adding the bacterial powder into a carbon source culture medium in an amount which accounts for 5-10% of the volume of the modifier, and uniformly mixing to obtain the water quality modifier.

Further preferably, the preparation method of the water quality modifier for large-scale prawn culture comprises the following steps:

(1) and (3) microbial fermentation: inoculating composite bacillus strain at 10m under aseptic condition³In the microbial fermentation culture medium of the fermentation tank, the inoculation amount is 4-5% of the total volume of the culture medium, and the inoculation amount is 180-200 r.min at 30-32 DEG C^-1Continuously ventilating and fermenting for 90 hours to obtain fermentation liquor;

(2) and (3) drying: filter pressing the fermentation liquor by a filter press, ultrafiltering, concentrating, and spray drying to obtain dried bacteria powder of the fermentation liquor;

(3) mixing: adding the bacterial powder into a carbon source culture medium in an amount which accounts for 5-10% of the volume of the modifier, and uniformly mixing to obtain the water quality modifier.

In the preparation method, the fermentation liquor obtained in the step 1 contains bacillus with viable count of 15 x 10⁹cfu/mL fermentation broth.

In the preparation method, the microbial fermentation culture medium and the carbon source culture medium are both the microbial fermentation culture medium and the carbon source culture medium described in the water quality modifier.

In a third aspect, the water quality improver prepared by the preparation method is provided.

Compared with the existing water quality modifier, the invention has the beneficial effects that:

(1) compared with the method of singly adding carbon source types such as brown sugar, cane sugar or molasses which are commonly used in the market to adjust the C/N ratio of the aquaculture water body by an optimal carbon source culture medium, the method has the advantages of wide material sources, less consumption, low cost and the like.

(2) The composite bacillus for fermentation has obvious inhibition effect on common vibrio parahaemolyticus of shrimps, and can reduce the occurrence of prawn diseases; the research proves that the bacillus compositus has the characteristic of high yield of cellulase, continuous decomposition of the cellulase-producing bacteria and a suitable natural cellulose substrate can be realized by putting the cellulase-producing bacteria and the suitable natural cellulose substrate into a prawn culture environment, a carbon source is provided for the culture environment, the C/N of a water body is improved, the regulation technology is optimized, and the technical cost is reduced.

(3) The composite bacillus for fermentation has a synergistic effect, and compared with the respective use of three independent strains or the composite of other strains, the test proves that the effect is greatly enhanced.

(4) The active substances added into the carbon source culture medium, particularly the components and the content proportion of the active substances, can effectively promote the mass propagation of the bacillus compositus and other probiotics in the water body, so that the beneficial bacteria have a dominant position in the water body, and the inhibition effect on harmful bacteria is enhanced.

(5) The carbon source and the probiotic adding are effectively combined together, so that an effective and long-term C/N regulation action system can be formed; thereby continuously promoting the growth of beneficial bacteria in the culture environment, reducing the level of toxic inorganic nitrogen compounds, inhibiting the propagation of harmful bacteria, forming a large amount of biological floccules and providing a good environment for the growth of prawns.

Drawings

FIG. 1 is a graph showing the results of the carbon-nitrogen ratio of the culture water of test example 1.

FIG. 2 is a graph showing the results of the carbon-nitrogen ratio of the culture water of test example 2.

FIG. 3 is a graph showing the results of the carbon-nitrogen ratio of the culture water of test example 4.

FIG. 4 is a graph showing the results of the carbon-nitrogen ratio of the culture water of test example 5.

FIG. 5 is a graph showing the results of measurement of the Vibrio subnatans quantity in test example 5.

FIG. 6 is a graph showing the results of total number of Bacillus recombinans in test example 5.

FIG. 7 is a graph showing the results of the nitrogen nitrate content in test example 6.

FIG. 8 is a graph showing the results of the inorganic nitrogen content in test example 6.

FIG. 9 is a graph showing the results of the phosphate content in test example 6.

Detailed Description

The present invention is further illustrated by the following specific examples.

In the embodiment of the invention, the composition of the bacillus compositus comprises the following components in parts by weight: 5 parts of bacillus subtilis, 3 parts of bacillus licheniformis and 2 parts of bacillus coagulans.

In the embodiment of the invention, the multi-mineral premix comprises the following components in percentage by weight: 3% of zinc sulfate monohydrate, 2% of manganese sulfate monohydrate, 5% of ferrous sulfate and 90% of rice chaff.

In the embodiment of the invention, the active substance comprises the following components in percentage by weight: 5% glucanase, 1% CPPS, 0.5% biotin and 93.5% starch.

Example 1

A preparation method of a water quality modifier for prawn culture comprises the following steps:

(1) and (3) microbial fermentation: inoculating composite bacillus strain at 10m under aseptic condition³In the microbial fermentation culture medium of the fermentation tank, the inoculation amount is 4-5% of the total volume of the culture medium, and the inoculation amount is 180-200 r.min at 30-32 DEG C^-1And continuously ventilating and fermenting for 90 hours to obtain fermentation liquor, wherein the microbial fermentation culture medium comprises the following raw materials in parts by weight: 70 parts of straw powder, 20 parts of wheat bran, 3 parts of peptone, 1 part of beef extract, 4 parts of ammonium sulfate, 0.5 part of monopotassium phosphate and 0.2 part of magnesium sulfate;

(2) and (3) drying: filter pressing the fermentation liquor by a filter press, ultrafiltering, concentrating, and spray drying to obtain dried bacteria powder of the fermentation liquor;

(3) mixing: adding the bacterial powder into a carbon source culture medium in an amount which accounts for 5-10% of the volume percent of the modifying agent, and uniformly mixing to obtain the water quality modifying agent, wherein the carbon source culture medium comprises the following raw materials in parts by weight: 15 parts of straw powder, 20 parts of rice chaff, 5 parts of straw powder, 5 parts of multi-mineral premix and 3 parts of active substances.

Test example 1

With a base area of 0.2m²And carrying out outdoor culture experiment on the penaeus vannamei boone by using a 2000L drum. The initial juvenile shrimp length is 1.5 + -0.1 cm, and the breeding density is 200 tail/m²And paving bottom mud with the thickness of 5cm at the bottom of the bucket as a substrate. Black sunshade net and air stone installed on cultivation barrelAnd (6) inflating. Reservoir seawater is used as a water source. The whole culture period does not exchange water with the outside except for supplementing evaporated water (tap water).

Commercial penaeus vannamei feed (30% crude protein) was fed at 6 and 17 points per day. The bait feeding rate is gradually reduced from 10 percent of the initial weight of the prawns to 4 percent of the later period of the experiment. The prawn water quality modifier prepared in the embodiment 1 of the invention is used as a carbon source for experiments, brown sugar is used as a carbon source of a control group, the carbon source is dissolved at 10 points every day and then added into aquaculture water, and the adding amount is 100g/m³Each treatment group was set in triplicate.

The total carbon in the water body is measured by sampling every 10 days in the culture process, and the result is shown in figure 1.

FIG. 1 shows that compared with brown sugar with a single carbon source, the water quality improver has the effects of reducing the consumption and quickly adjusting the C/N of a water body.

Test example 2

With a base area of 0.2m²And carrying out outdoor culture experiment on the penaeus vannamei boone by using a 2000L drum. The initial juvenile shrimp length is 1.5 + -0.1 cm, and the breeding density is 200 tail/m²And paving bottom mud with the thickness of 5cm at the bottom of the bucket as a substrate. The cultivation barrel is provided with shading cloth and air inflation stone. Reservoir seawater is used as a water source. The whole culture period does not exchange water with the outside except for supplementing evaporated water (tap water).

Commercial penaeus vannamei feed (30% crude protein) was fed at 6 and 17 points per day. The bait feeding rate is gradually reduced from 10 percent of the initial weight of the prawns to 4 percent of the later period of the experiment. The prawn water quality modifier prepared in the embodiment 1 of the invention is used as a carbon source for experiments, brown sugar is used as a carbon source of a control group, and the prawn water quality modifier is dissolved at 10 points every day and then added into a culture water body. The addition amount of the carbon source refers to a calculation formula provided by Avnimelech

ΔCH＝(Feed×N_feed×N_excretion)/0.05

In the formula: delta CH carbon source addition; feed is the feeding amount; n is a radical of_feedIs the nitrogen content of the feed, N_excretionThe proportion of nitrogen excreted by the farmed animals to the nitrogen of the fed feed (generally 50%); 0.05 is a constant.

The addition amount of the water quality modifier is 100 percent of the theoretical addition amount of the carbon source (calculated that the addition amount of the water quality modifier is 150 g/m)³(ii) a The brown sugar is added in an amount of about 300g/m³) Each treatment group was set in triplicate.

Samples were taken every 10 days during the cultivation process to determine the total carbon in the water, and the results are shown in fig. 2.

FIG. 2 shows that the water quality modifier of the invention has the effects of less dosage and rapid adjustment of C/N of water body compared with a single carbon source.

In addition, the applicant also proves that the component selection and the content ratio in the carbon source have obvious positive significance for quickly adjusting the C/N of the water body, reducing the dosage and the like through other tests.

Test example 3

With a base area of 0.2m²And carrying out outdoor culture experiment on the penaeus vannamei boone by using a 2000L drum. The initial juvenile shrimp length is 1.5 + -0.1 cm, and the breeding density is 200 tail/m²And paving bottom mud with the thickness of 5cm at the bottom of the bucket as a substrate. The cultivation barrel is provided with shading cloth and air inflation stone. Reservoir seawater is used as a water source. The whole culture period does not exchange water with the outside except for supplementing evaporated water (tap water).

Commercial penaeus vannamei feed (30% crude protein) was fed at 6 and 17 points per day. The bait feeding rate is gradually reduced from 10 percent of the initial weight of the prawns to 4 percent of the later period of the experiment. The prawn water quality modifier prepared in the embodiment 1 of the invention is used as a carbon source for experiments, is dissolved at 10 points every day and then is added into aquaculture water, the addition amount is 100 percent of the theoretical addition value of the carbon source, and a control group without any water quality modifier is used. Each treatment group was set in triplicate.

The experimental culture period is 100 days, and the growth parameters of the penaeus vannamei boone are measured after the experiment is finished, wherein the growth parameters mainly comprise the yield, the survival rate and the bait coefficient of the penaeus vannamei boone. The results of the experiment are shown in table 1:

TABLE 1

Item	Control group	Experimental group
			Yield (kg/m)2)	0.86±0.2	1.25±0.2
Survival rate (%)	55.61	72.07
			FCR	2.24	1.75

The results in table 1 show that the treated group added with the prawn water quality improver has a yield higher than that of the control group by more than 20%, and has obvious differences in survival rate and bait coefficient, so that the prawn water quality improver is added to adjust the C/N ratio in a water body, effectively stabilize water quality, reduce diseases and promote the growth of prawns.

Test example 4

With a base area of 0.2m²And carrying out outdoor culture experiment on the penaeus vannamei boone by using a 2000L drum. The initial juvenile shrimp length is 1.5 + -0.1 cm, and the breeding density is 200 tail/m²And paving bottom mud with the thickness of 5cm at the bottom of the bucket as a substrate. The cultivation barrel is provided with shading cloth and air inflation stone. Reservoir seawater is used as a water source. The whole culture period does not exchange water with the outside except for supplementing evaporated water (tap water).

Commercial penaeus vannamei feed (30% crude protein) was fed at 6 and 17 points per day. The bait feeding rate is gradually reduced from 10 percent of the initial weight of the prawns to 4 percent of the later period of the experiment. The prawn water quality modifier is used as a carbon source for experiments, is dissolved at 10 points every day and then is added into aquaculture water, the addition amount is 100 percent of the theoretical addition value of the carbon source, three water quality modifiers purchased in the market are added into a control group, and are marked as quotient 1# (bacillus compositus-Jiangsu), quotient 2# (water adjusting pioneer-Shandong) and quotient 3# (water purifying Bao-Nanjing), and the addition amounts are all 100 percent of the theoretical addition value of the carbon source. Each treatment group was set in triplicate.

The experimental cultivation period is 100 days, the total carbon in the water body is measured by sampling every 10 days in the cultivation process, and the result is shown in figure 3; at the end of the experiment, the growth parameters of penaeus vannamei boone were measured, mainly including the yield, survival rate and bait coefficient of penaeus vannamei boone. The results are shown in Table 2.

Table 2:

the experimental results in table 2 and fig. 3 show that the water quality modifier of the invention has better effect than commercial No. 1, commercial No. 2 and commercial No. 3 water quality modifiers in the market no matter the water quality modifier has the growth promotion effect on prawns or the adjusting effect on C/N of aquaculture water. This effect may be relevant to the analysis of the aforementioned advantageous effects of the present invention.

Test example 5

With a base area of 0.2m²And carrying out outdoor culture experiment on the penaeus vannamei boone by using a 2000L drum. The initial juvenile shrimp length is 1.5 + -0.1 cm, and the breeding density is 200 tail/m²And paving bottom mud with the thickness of 5cm at the bottom of the bucket as a substrate. The cultivation barrel is provided with shading cloth and air inflation stone. Reservoir seawater is used as a water source. The whole culture period does not exchange water with the outside except for supplementing evaporated water (tap water).

Commercial penaeus vannamei feed (30% crude protein) was fed at 6 and 17 points per day. The bait feeding rate is gradually reduced from 10 percent of the initial weight of the prawns to 4 percent of the later period of the experiment. The prawn water quality modifier is used as a carbon source for experiments, is dissolved at 10 points every day and then is added into a culture water body, and the adding amount is 100 percent of the theoretical adding amount of the carbon source; two control groups are set, wherein the control group 1 is the water quality modifying agent without the active substance component, the control group 2 is the water quality modifying agent without the composite bacillus, the addition amount is 100 percent of the theoretical addition amount of the carbon source, and three treatment groups are arranged in parallel.

The experimental cultivation period is 100 days, the total carbon, the total number of the composite bacillus and the number of the bottom sediment vibrio in the water body are measured by sampling every 10 days in the cultivation process, and the results are shown in fig. 4, fig. 5 and fig. 6. At the end of the experiment, the growth parameters of penaeus vannamei boone, mainly including the yield, survival rate and bait coefficient of penaeus vannamei boone, were measured, and the results are shown in table 3

TABLE 3

Item	Experimental group	Control group 1	Control group 2
				Yield (kg/m)2)	1.32±0.2	1.08±0.2	0.82±0.2
Survival rate (%)	76.5	65.3	58.12
				FCR	1.55	1.75	2.02

As can be seen from the results of Table 3, FIG. 4, FIG. 5 and FIG. 6, the water quality improving agents of the complete components of the experimental group, the water quality improving agents of the present invention, whether the growth promoting effect on prawns or the C/N regulating effect on aquaculture water, are superior to the control groups 1 and 2 lacking the components. Therefore, the composite bacillus and the active substance in the water quality modifier are important components, and the water quality modifier is not necessary. The active substance can promote mass propagation of the bacillus compositus in the modifying agent in the aquaculture water body, and the propagated bacillus compositus can improve C/N of the water body, inhibit propagation of vibrio and ensure healthy growth of prawns.

Test example 6 elevated tank effect test

The density of the seedlings placed is about 1000 tails/m²In the intensive culture high-level pond for the penaeus vannamei boone, the influence of the addition of the water quality improver for the penaeus vannamei boone on the water quality index of the culture water body is researched. The test is divided into a control group and a treatment group, wherein each group is respectively provided with 3 parallel ponds, and the control group is in a conventional water changing culture mode. And at the first 24d, changing water by 30cm every 3 d. And changing water for 24-40 days, and changing water for every 3 days by 50 cm. After 40 days, the water was changed every 2 days for 50 cm. The prawn water quality modifier is added into the processing group, and 1m plastic bucket is added into a 1m x 1.5m x 1.2m plastic bucket in order to enhance the using effect of the water quality modifier³2kg of prawn water quality modifier is added into tap water, and after continuous aerated fermentation is carried out for 72 hours at the temperature of 23-33 ℃, the ratio of 2kg/m³3d adding and treating the group aquaculture water body. The bait amount was maintained at the same level for both the control group and the treatment group based on the estimated number of surviving shrimps.

After the experiment begins, 1000ml of water and 1000ml of water sample at a water outlet are respectively taken from 4 corners of each experiment pool and the middle layer of the center of the pool every 4-5 days, the water samples are uniformly mixed, 1000ml of the water sample is taken from the water samples and is placed in a measuring cylinder for 30min, the shape of flocculent precipitates is observed by a biological microscope, supernatant is filtered by a 0.45 mu m microporous filter membrane, and filtrate is used for measuring water quality indexes.

The experimental results are as follows:

(1) observation of biological floc formation phenomena the water transparency of the water body of the prawn water quality modifier treatment group added in the invention is obviously reduced from the 7 th day of culture. On day 14, the transparency of the water body of the treatment group is reduced to 20cm, and the water color is earthy yellow, while the transparency of the water body of the control group is 30cm, and the water color is light green. The water sample is taken by using the measuring cylinder, floc with the size not more than 5mm can be observed to float in the water of the treated group, and the floating floc can be observed by using a microscope, so that a large amount of microorganisms, unicellular algae, protozoa, limnodrilus, and the like are contained in the floc, which indicates that biological floc is formed.

(2) The measuring result of the nitrate nitrogen content of the aquaculture water body is shown in FIG. 7, and the result shows that the nitrate nitrogen content level of each group is very low and changes little in the aquaculture period of 1-15 d; in the culture period of 15-36 d, the average nitric acid nitrogen content of the control group is rapidly increased to be in the range of 3.05-4.52 mg/L, the treatment group starts to increase after 28d, and reaches the highest point of the whole culture period in 32-36 d, and the average nitric acid nitrogen content is 2.78 mg/L; after 36d of culture, the nitric acid nitrogen of the control group fluctuates within the range of 1.12-4.6 mg/L for most of time, and the average nitric acid nitrogen content of the treatment group is always lower than 1.3 mg/L.

(3) The results of the change in the inorganic nitrogen content in the culture water are shown in FIG. 8. According to the water consumption in the whole culture process, the inorganic nitrogen generation amount of the unit culture area is calculated to be 50g/m²Treatment group was 4g/m²。

(4) The measurement result of the phosphate content of the aquaculture water body is shown in fig. 9, and the result shows that the content of active phosphate in each group is maintained at a lower level in the whole aquaculture process, wherein the average content of phosphate in the treatment group is in a trend of rising firstly and then falling when the treatment group is cultured for 15-66 days, and reaches the highest 0.068mg/L when the treatment group is cultured for 36 days; the average phosphate content of the control group was at an extremely low level of 0.007mg/L most of the time, but only reached a low level of 0.015mg/L at 16d and 62-70 d.

The experimental results show that the prawn water quality modifier provided by the invention is added into the aquaculture water body, and the C/N ratio in the aquaculture water body is adjusted, so that the reproduction of heterotrophic microorganisms can be promoted, protozoan communities taking the heterotrophic microorganisms as food are increased, and a plurality of microorganisms gradually form flocculent colonies through biological flocculation. The heterotrophic microorganisms consume inorganic nitrogen in the culture water as a nitrogen source required by growth and propagation of the heterotrophic microorganisms, so that the water quality is effectively stabilized; meanwhile, a microbial protein source is added to protozoa, micro zooplankton and cultured animals, and the healthy growth of the prawns is promoted.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and their concepts should be considered to be equivalent or modified within the technical scope of the present invention.

Claims (8)

1. The water quality improver for prawn culture is characterized by comprising a carbon source culture medium and bacterial powder of fermentation liquor of dried microbial strains, wherein the carbon source culture medium comprises the following raw materials in parts by weight: 10-15 parts of straw powder, 15-20 parts of rice chaff, 5-10 parts of straw powder, 5-10 parts of multi-mineral premix and 3-5 parts of active substances; the fermentation liquid of the microbial strain is obtained by fermenting the microbial strain in a microbial fermentation culture medium, wherein the microbial strain comprises compound bacillus, the compound bacillus comprises bacillus subtilis, bacillus licheniformis and bacillus coagulans, and the microbial fermentation culture medium comprises the following raw materials in parts by weight: 60-70 parts of straw powder, 20-30 parts of wheat bran, 3-5 parts of peptone, 1-3 parts of beef extract, 3-6 parts of ammonium sulfate, 0.3-0.6 part of monopotassium phosphate and 0.1-0.3 part of magnesium sulfate;

the water quality modifier for prawn culture is prepared by the following method:

(1) and (3) microbial fermentation: inoculating the composite bacillus strain in a microbial fermentation culture medium, wherein the inoculation amount is 4-5% of the total volume of the culture medium, and the inoculation amount is 180-200 r.min at 30-32 DEG C^-1Continuous aerationFermenting for 90 hours to obtain fermentation liquor;

(2) and (3) drying: drying the fermentation liquor to obtain the bacterial powder of the fermentation liquor of the dried microbial strains;

(3) mixing: adding the bacterial powder into a carbon source culture medium in an amount which accounts for 5-10% of the volume of the modifier, and mixing to obtain the water quality modifier.

2. The water quality improver for prawn culture according to claim 1, wherein the microbial fermentation medium comprises the following raw materials in parts by weight: 70 parts of straw powder, 20 parts of wheat bran, 3 parts of peptone, 1 part of beef extract, 4 parts of ammonium sulfate, 0.5 part of monopotassium phosphate and 0.2 part of magnesium sulfate.

3. The water quality improver for prawn culture according to claim 1, wherein the carbon source culture medium comprises the following raw materials in parts by weight: 15 parts of straw powder, 20 parts of rice chaff, 5 parts of straw powder, 5 parts of multi-mineral premix and 3 parts of active substances.

4. The water quality improver for prawn culture according to claim 1, wherein the composition of the bacillus compositus is bacillus subtilis, bacillus licheniformis and bacillus coagulans.

5. A preparation method of the water quality improver for prawn culture according to any one of claims 1 to 4, which is characterized by comprising the following steps:

(1) and (3) microbial fermentation: inoculating the composite bacillus strain in a microbial fermentation culture medium, wherein the inoculation amount is 4-5% of the total volume of the culture medium, and the inoculation amount is 180-200 r.min at 30-32 DEG C^-1Continuously ventilating and fermenting for 90 hours to obtain fermentation liquor;

(2) and (3) drying: drying the fermentation liquor to obtain the bacterial powder of the fermentation liquor of the dried microbial strains;

(3) mixing: adding the bacterial powder into a carbon source culture medium in an amount which accounts for 5-10% of the volume of the modifier, and mixing to obtain the water quality modifier.

6. The preparation method of the water quality improver for prawn culture according to claim 5, characterized by comprising the following steps:

(1) and (3) microbial fermentation: inoculating the composite bacillus strain into a microbial fermentation culture medium, wherein the inoculation amount is 4-5% of the total volume of the culture medium, and the temperature is 30-32 ℃ and the inoculation amount is 180-200 r.min^-1Continuously ventilating and fermenting for 90 hours at a rotating speed to obtain fermentation liquor;

(2) and (3) drying: filter-pressing the fermentation liquor, ultrafiltering, concentrating, and spray drying to obtain dry powder of fermentation liquor of microorganism strain;

(3) mixing: adding the bacterial powder into a carbon source culture medium in an amount which accounts for 5-10% of the volume of the modifier, and uniformly mixing to obtain the water quality modifier.

7. The preparation method of the water quality improver for prawn culture according to claim 5, characterized by comprising the following steps:

(1) and (3) microbial fermentation: inoculating composite bacillus strain at 10m under aseptic condition³In the microbial fermentation culture medium of the fermentation tank, the inoculation amount is 4-5% of the total volume of the culture medium, and the inoculation amount is 180-200 r.min at 30-32 DEG C^-1Continuously ventilating and fermenting for 90 hours to obtain fermentation liquor;

(2) and (3) drying: filter-pressing the fermentation liquor by a filter press, performing ultrafiltration concentration and spray drying to obtain the bacterial powder of the fermentation liquor of the dry microbial strains;

(3) mixing: adding the bacterial powder into a carbon source culture medium in an amount which accounts for 5-10% of the volume of the modifier, and uniformly mixing to obtain the water quality modifier.

8. The method for preparing a water quality improver for prawn culture according to claim 5, wherein the fermentation broth obtained in the step (1) contains bacillus with a viable count of 15 x 10⁹cfu/mL fermentation broth.