Compound microbial agent, preparation method thereof and application of compound microbial agent in aquatic feed

Abstract

The invention discloses a compound microbial agent as well as a preparation method and application thereof in aquatic feed, and belongs to the technical field of microorganisms. The invention provides compound microorganism bacterium powder based on bacillus velezensis QCS-426, bacillus H68 and lactobacillus plantarum T80, fish meal, soybean meal and high gluten flour are added to obtain a compound microorganism bacterium agent, and finally the compound microorganism bacterium agent is prepared into aquatic feed. According to a feeding experiment result, compared with a conventional aquatic feed, the weight gain rate and the specific growth rate of the juvenile sebastes schlegeli are increased by feeding the juvenile sebastes schlegeli with the aquatic feed, the feed coefficient is reduced, and the effect is very remarkable. The results show that after the compound microbial agent provided by the invention is mixed with the aquatic basal feed, the nutrition of the aquatic feed is enriched, the digestion and absorption of the aquatic animals are facilitated, the growth performance of the aquatic animals can be obviously improved, and the application prospect is wide.

Description

Technical Field

[0001] The present invention relates to the field of microbial applications, and particularly to a compound microbial agent, a preparation method thereof, and an application thereof in aquatic feed. Background Art

[0002] The global consumption of edible fish is growing rapidly every year, and the contribution of aquaculture to the global fish production is increasing rapidly. In order to meet the rapidly growing demand for fish, it is necessary to develop aquaculture production practices to a higher level in terms of technology and practice.

[0003] The growth of aquaculture production demand is accompanied by many challenges, among which disease outbreaks are the main factors hindering the development of the aquaculture industry. In the past few decades and even today, antibiotics are often used to control and prevent diseases in the aquaculture process, promote the growth of aquatic products, and improve feed efficiency. However, most antibiotics can only treat diseases, cannot solve the basic problems, and at the same time cause two major hazards: antibiotic residues and antibiotic resistance.

[0004] As a green and safe alternative to antibiotics, feed microbial preparations have a completely different mechanism of action from antibiotics and have received great attention in recent years. These preparations are prepared by processes such as fermentation and purification from natural beneficial microbial strains, and have the advantages of improving feed utilization rate, improving nutrition, promoting animal growth, maintaining the balance of intestinal microecology, and enhancing the immunity of aquaculture products. Microbial preparations can also improve the water quality of aquaculture and effectively reduce antibiotic residues and resistance pollution, etc., and play an important role in maintaining the health of aquatic organisms. The function of a single microbial preparation is relatively limited, and its environmental adaptability is poor, making it difficult to meet the actual aquaculture needs. Compound microbial preparations can significantly improve their environmental adaptability and comprehensive efficacy by reasonably combining strains with complementary functions, such as Bacillus and Lactobacillus. These preparations not only have the functions of preventing diseases and promoting growth, but also can improve the intestinal flora of aquatic products, thereby improving the quality of aquatic products, optimizing the aquaculture water environment, providing important technical support for the green development of aquaculture, and being an ideal future alternative to antibiotics. Summary of the Invention

[0005] The object of the present invention is to provide a compound microbial agent, a preparation method thereof, and an application thereof in aquatic feed to solve the problems existing in the above-mentioned prior art. The present invention provides a compound microbial preparation suitable for aquaculture. By optimizing the ratio of different microorganisms, this preparation aims to improve the feed conversion efficiency, enhance the growth performance and immune ability of aquaculture animals, and effectively reduce the use of antibiotics to achieve the production of antibiotic-free aquatic products.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a composite microbial powder, which includes Bacillus velezensis QCS-426, Bacillus sp. H68, and Lactobacillus plantarum T80;

[0008] The Bacillus velezensis QCS-426 is deposited in the China General Microbiological Culture Collection Center, with the deposit number CGMCC No. 33327, the deposit date being January 8, 2025, and the deposit address being No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing;

[0009] The Bacillus sp. H68 is deposited in the China General Microbiological Culture Collection Center, with the deposit number CGMCC No. 33326, the deposit date being January 8, 2025, and the deposit address being No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing;

[0010] The Lactobacillus plantarum T80 is deposited in the China General Microbiological Culture Collection Center, with the deposit number CGMCC No. 33328, the deposit date being January 7, 2025, and the deposit address being No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

[0011] Preferably, in the composite microbial powder, the total effective viable count of the Bacillus velezensis QCS-426, the Bacillus sp. H68, and the Lactobacillus plantarum T80 is not less than 8.5 - 9.5×10 10 cfu / g;

[0012] The ratio of the effective viable counts of the Bacillus velezensis QCS-426, the Bacillus sp. H68, and the Lactobacillus plantarum T80 is (3 - 5):(3 - 5):(90 - 95).

[0013] The present invention also provides a preparation method of the above-mentioned composite microbial powder, including the following steps:

[0014] Activating the Bacillus velezensis QCS-426 and the Bacillus sp. H68 respectively, conducting seed culture and fermentation for scale-up culture using LB liquid medium, centrifuging the fermentation broth, collecting the precipitate, adding skimmed milk powder with a mass fraction of 5 - 10% and mannitol with a mass fraction of 5 - 10%, and performing vacuum freeze-drying to obtain the powder of the Bacillus velezensis QCS-426 and the powder of the Bacillus sp. H68;

[0015] Activate the Lactobacillus plantarum T80, conduct seed culture and fermentation for scale-up culture using MRS liquid medium, centrifuge the fermentation broth, collect the precipitate, add skim milk powder with a mass fraction of 5-10% and mannitol with a mass fraction of 5-10%, and perform vacuum freeze-drying to obtain the bacterial powder of Lactobacillus plantarum T80;

[0016] Weigh 3-5 parts by weight of the bacterial powder of Bacillus velezensis QCS-426, 3-5 parts by weight of the bacterial powder of Bacillus sp. H68, and 90-94 parts by weight of the bacterial powder of Lactobacillus plantarum T80, and mix them evenly to obtain the composite microbial bacterial powder.

[0017] Preferably, the viable count of the bacterial powder of Bacillus velezensis QCS-426 is 8.5-9.5×10 10 cfu / g; the viable count of the bacterial powder of Bacillus sp. H68 is 8.5-9.5×10 10 cfu / g; the viable count of the bacterial powder of Lactobacillus plantarum T80 is 8.5-9.5×10 10 cfu / g.

[0018] The present invention also provides a composite microbial inoculant, including the above-mentioned composite microbial bacterial powder.

[0019] Preferably, by weight, it includes the following components: 0.5-1.5 parts of the composite microbial bacterial powder, 19-21 parts of fish meal, 34-36 parts of soybean meal, and 41.5-46.5 parts of high-gluten flour.

[0020] The present invention also provides an application of the above-mentioned composite microbial bacterial powder or the above-mentioned composite microbial inoculant in the preparation of aquatic feed.

[0021] The present invention also provides an aquatic feed, including the above-mentioned composite microbial inoculant.

[0022] Preferably, it further includes a basic feed; the mass ratio of the composite microbial inoculant to the basic feed is 1:2000.

[0023] The present invention also provides a method for culturing aquatic products, including the following steps:

[0024] Put the above-mentioned composite microbial bacterial powder and / or the above-mentioned composite microbial inoculant into the breeding area;

[0025] And / or, feed the above-mentioned aquatic feed.

[0026] The present invention discloses the following technical effects:

[0027] The present invention provides a composite microbial powder based on Bacillus velezensis QCS-426, Bacillus sp. H68 and Lactobacillus plantarum T80, and fish meal, soybean meal and high-gluten flour are added to obtain a composite microbial agent, and finally an aquatic feed is prepared. According to the feeding experiment results, compared with the conventional aquatic feed, feeding the aquatic feed of the present invention increases the weight gain rate and specific growth rate of juvenile Sebastes schlegelii, and reduces the feed coefficient, and the effect is very significant. The above results show that after mixing the composite microbial agent provided by the present invention with the basic aquatic feed, the nutrition of the aquatic feed is enriched, which is more conducive to the digestion and absorption of aquatic animals, can significantly improve the growth performance of aquatic animals, and has broad application prospects. Brief Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings.

[0029] Figure 1 It is the colony morphology diagram of Bacillus velezensis QCS-426;

[0030] Figure 2 It is the colony morphology diagram of Bacillus sp. H68;

[0031] Figure 3 It is the colony morphology diagram of Lactobacillus plantarum T80;

[0032] Figure 4 It is the colony morphology diagram of Bacillus velezensis QCS-426 under scanning electron microscope;

[0033] Figure 5 It is the colony morphology diagram of Bacillus sp. H68 under scanning electron microscope;

[0034] Figure 6 It is the colony morphology diagram of Lactobacillus plantarum T80 under scanning electron microscope;

[0035] Figure 7 It is the phylogenetic tree diagram of Bacillus velezensis QCS-426; wherein, strain QCS-426 is Bacillus velezensis QCS-426;

[0036] Figure 8 It is the phylogenetic tree diagram of Bacillus sp. H68; wherein, strain H68 is Bacillus sp. H68;

[0037] Figure 9 It is the phylogenetic tree diagram of Lactobacillus plantarum T80; wherein, strain T80 is Lactobacillus plantarum T80;

[0038] Figure 10 It is the growth curve of Bacillus velezensis QCS-426;

[0039] Figure 11 It is the growth curve of Bacillus sp. H68;

[0040] Figure 12 It is the growth curve of Lactobacillus plantarum T80. Detailed implementation manners

[0041] The various exemplary implementation manners of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0042] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0043] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0044] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other implementation manners obtained from the present invention specification are also obvious to those skilled in the art. The present invention specification and examples are only exemplary.

[0045] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0046] The medium formulations involved in the embodiments of the present invention are as follows:

[0047] LB medium: 10 g of tryptone, 5 g of yeast extract powder, 10 g of sodium chloride, made up to 1 L with deionized water, pH 7.0, sterilized at 121 °C for 20 min.

[0048] LB solid medium: 10 g of tryptone, 5 g of yeast extract powder, 10 g of sodium chloride, 15 g of agar, made up to 1 L with deionized water, pH 7.0, sterilized at 121 °C for 20 min.

[0049] MRS medium: 10 g of peptone, 8 g of beef extract powder, 4 g of yeast extract powder, 20 g of glucose, 2 g of dipotassium hydrogen phosphate, 2 g of diammonium hydrogen citrate, 5 g of sodium acetate, 0.2 g of magnesium sulfate, 0.04 g of manganese sulfate, 1.0 g of Tween 80, made up to 1 L with deionized water, pH 5.7, sterilized at 118 °C for 15 min.

[0050] MRS solid medium: 10 g of peptone, 8 g of beef extract powder, 4 g of yeast extract powder, 20 g of glucose, 2 g of dipotassium hydrogen phosphate, 2 g of diammonium hydrogen citrate, 5 g of sodium acetate, 0.2 g of magnesium sulfate, 0.04 g of manganese sulfate, 1.0 g of Tween 80, 15 g of agar, made up to 1 L with deionized water, pH 6.2, sterilized at 121 °C for 20 min.

[0051] Example 1

[0052] I. Identification and properties of strains

[0053] 1. Observation of strain morphology

[0054] (1) Strain activation

[0055] Bacillus velezensis QCS-426 and Bacillus sp. H68 were streaked on LB solid medium and cultured at 37 °C for 18 h. Lactobacillus plantarum T80 was inoculated on MRS solid medium and cultured at 30 °C for 24 h.

[0056] (2) Morphological observation

[0057] Bacillus velezensis QCS-426 and Bacillus sp. H68 were streaked on LB solid medium and cultured at 37 °C for 18 h. Lactobacillus plantarum T80 was inoculated on MRS solid medium and cultured at 30 °C for 24 h. The colony morphology was observed.

[0058] (3) Liquid culture

[0059] Single colonies of Bacillus velezensis QCS-426 and Bacillus sp. H68 were picked and cultured in LB medium at 37 °C, 180 rpm for 12 h. A single colony of Lactobacillus plantarum T80 was picked and cultured statically in MRS medium at 30 °C for 12 h.

[0060] (4) Scanning electron microscopy observation

[0061] Take 1 mL of each of the Bacillus velezensis QCS-426, Bacillus sp. H68, and Lactobacillus plantarum T80 bacterial solutions. After centrifugation, fix them overnight with 2.5% glutaraldehyde. After gradient elution with ethanol, aspirate a small amount of the bacterial solution onto a silicon wafer, sputter gold, and then observe under a scanning electron microscope.

[0062] 2. Strain identification

[0063] Use PCR to amplify the 16S rRNA gene of the strains. Submit the sequencing results of Bacillus velezensis QCS-426, Bacillus sp. H68, and Lactobacillus plantarum T80 to NCBI GenBank respectively, perform sequence analysis using the BLAST program, and draw a phylogenetic tree based on the results.

[0064] 3. Strain growth curve

[0065] Streak Bacillus velezensis QCS-426 and Bacillus sp. H68 on LB solid medium and culture at 37 °C for 18 h. Inoculate Lactobacillus plantarum T80 on MRS solid medium and culture at 30 °C for 24 h.

[0066] Measure the OD 600 value of the seed solution. Add the seed solution to the medium respectively so that the initial OD 600 value is 0.02, place it at the optimal temperature for culture, and measure the OD 600 value every 2 h.

[0067] 4. Strain preservation

[0068] Bacillus velezensis QCS-426 is preserved in the China General Microbiological Culture Collection Center, with the preservation number CGMCC No. 33327, the preservation date is January 8, 2025, and the preservation address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing;

[0069] Bacillus sp. H68 is preserved in the China General Microbiological Culture Collection Center, with the preservation number CGMCC No. 33326, the preservation date is January 8, 2025, and the preservation address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing;

[0070] Lactobacillus plantarum T80 is preserved in the China General Microbiological Culture Collection Center, with the preservation number CGMCC No. 33328, the preservation date is January 7, 2025, and the preservation address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing.

[0071] II. Preparation of Compound Microbial Inoculum

[0072] 1. Preparation of Microbial Bacterial Powder

[0073] (1) Preparation Method of Bacillus velezensis QCS-426 and Bacillus sp. H68 Bacterial Powders

[0074] The same bacterial powder preparation method is used for the two strains of Bacillus velezensis:

[0075] Inoculate Bacillus velezensis on LB solid medium and culture at 37 °C for 18 h.

[0076] Take a single colony of Bacillus velezensis from the LB solid medium and inoculate it into LB liquid medium. Culture at 37 °C and 180 r / min for 12 h to obtain the Bacillus velezensis seed liquid.

[0077] Inoculate from the seed liquid at an inoculation amount of 1% by volume into LB liquid medium. Culture at 37 °C and 180 r / min for 12 h to obtain the Bacillus velezensis fermentation broth.

[0078] Centrifuge the Bacillus velezensis fermentation broth to obtain bacterial sludge. Add skim milk powder at a mass ratio of 5 - 10% and mannitol at a mass ratio of 5 - 10%. After vacuum freeze-drying, obtain the bacterial powder, and the viable bacteria count in the bacterial powder is 8.5 - 9.5×10 10 cfu / g.

[0079] (2) Preparation Method of Lactobacillus plantarum T80 Bacterial Powder

[0080] Inoculate Lactobacillus plantarum on MRS solid medium and culture at 30 °C for 24 h.

[0081] Take a single colony of Lactobacillus plantarum from the MRS solid medium and inoculate it into MRS liquid medium. Culture statically at 37 °C for 18 h to obtain the Lactobacillus plantarum seed liquid.

[0082] Inoculate from the seed liquid at an inoculation amount of 1% by volume into MRS liquid medium. Culture statically at 30 °C for 36 h to obtain the Lactobacillus plantarum fermentation broth.

[0083] Centrifuge the Lactobacillus plantarum fermentation broth to obtain bacterial sludge. Add skim milk powder at a mass ratio of 5 - 10% and mannitol at a mass ratio of 5 - 10%. After vacuum freeze-drying, obtain the bacterial powder, and the viable bacteria count in the bacterial powder is 8.5 - 9.5×10 10 cfu / g.

[0084] 2. Preparation of Compound Microbial Inoculum

[0085] Weigh 0.3 - 0.5 g of Bacillus velezensis QCS - 426 powder, 0.3 - 0.5 g of Bacillus sp. H68 powder and 9.0 - 9.5 g of Lactobacillus plantarum T80 powder, and mix them evenly to obtain a composite microbial powder.

[0086] Take 0.5 - 1.5 g of the composite microbial powder, 19 - 21 g of fish meal, 34 - 36 g of soybean meal and 41.5 - 46.5 g of high - gluten flour, mix them to prepare a composite microbial agent.

[0087] 3. Preparation of feed additive for the control group

[0088] Weigh 19 - 21 g of fish meal, 34 - 36 g of soybean meal and 43 - 47 g of high - gluten flour, and mix them to prepare the feed additive for control group 1.

[0089] Weigh 0.3 - 0.5 g of Bacillus velezensis QCS - 426 powder, 0.3 - 0.5 g of Bacillus sp. H68 powder, 19 - 21 g of fish meal, 34 - 36 g of soybean meal and 42 - 46.4 g of high - gluten flour, and mix them to prepare the feed additive for control group 2.

[0090] III. Application of the composite microbial agent in aquaculture feed

[0091] The basic feed components for aquaculture animals in the present invention are: 200 g of fish meal, 200 g of peanut meal, 100 g of chicken meal, 100 g of soybean meal powder, 100 g of corn flour, 100 g of flour, 60 g of rice bran, 25 g of squid powder, 30 g of sodium alginate, 20 g of protein powder, 20 g of shrimp shell powder, 20 g of soybean phospholipid oil.

[0092] Mix the prepared composite microbial agent with the basic feed for aquaculture animals. Add 0.5 g of the agent per 1 kg of feed to obtain the feed for the experimental group; feed the blank group with feed without adding any substances; feed the control group with feed containing the above - mentioned feed additive for the control group (the addition amount is 0.5 g / kg); there are 80 juvenile Sebastes schlegelii in each group, and they are fed 3 times a day for a total of 60 days.

[0093] Try to ensure that the breeding conditions of all groups are the same. Weigh the weight and body length of each fish at the beginning of the experiment, and measure the weight and body length of each fish at the end of the experiment, and calculate the weight gain rate, specific growth rate, feed conversion ratio, viscerosomatic index, hepatosomatic index, intestinosomatic index, condition factor.

[0094] IV. Experimental results

[0095] 1. Observation of colony morphology of strains

[0096] The colony morphologies of Bacillus velezensis QCS - 426, Bacillus sp. H68 and Lactobacillus plantarum T80 are as Figures 1 - 3 shown.

[0097] 2. Morphological Observation of Strains by Scanning Electron Microscope

[0098] The morphologies of Bacillus velezensis QCS-426, Bacillus sp. H68, and Lactobacillus plantarum T80 under scanning electron microscope are as Figures 4 - 6 shown.

[0099] 3. Strain Identification

[0100] The phylogenetic trees of Bacillus velezensis QCS-426, Bacillus sp. H68, and Lactobacillus plantarum T80 are as Figures 7 - 9 shown.

[0101] 4. Growth Curves of Strains

[0102] The growth curves of Bacillus velezensis QCS-426, Bacillus sp. H68, and Lactobacillus plantarum T80 are as Figures 10 - 12 shown.

[0103] 5. Viable Bacteria Counts of Bacterial Agents

[0104] The viable bacteria counts in the bacterial powders of Bacillus velezensis QCS-426 and Bacillus sp. H68 are 8.5 - 9.5×10 10 cfu / g; the viable bacteria count in the bacterial powder of Lactobacillus plantarum T80 is 8.5 - 9.5×10 10 cfu / g

[0105] 6. Effects of Compound Microbial Bacterial Agent on the Growth of Juvenile Sebastes schlegelii

[0106] After feeding the feed supplemented with the compound microbial bacterial agent described in the present invention, compared with the blank group, the weight gain rate of juvenile Sebastes schlegelii in the experimental group increased by 44.94%, the specific growth rate increased by 17.46%, and the feed conversion ratio decreased by 31.09%. The effect was very significant and significantly better than that of the control group. This indicates that after mixing the compound microbial bacterial agent provided by the present invention with aquaculture feed, the nutrition is more abundant, which is more conducive to the digestion and absorption of aquatic animals, can significantly improve the growth performance of aquatic animals, and has broad application prospects.

[0107] Table 1 Effects of Feeds of Each Group on Juvenile Sebastes schlegelii

[0108]

[0109]

[0110] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the spirit of the present invention's design, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A composite microbial powder, characterized in that, It includes Bacillus velezensis QCS-426, Bacillus sp. H68 and Lactobacillus plantarum T80; The Bacillus velezensis QCS-426 is deposited in the General Microbiological Center of the China National Center for Biotechnology Development, with the deposit number CGMCC No. 33327, the deposit date being January 8, 2025, and the deposit address being No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing; The Bacillus sp. H68 is deposited in the General Microbiological Center of the China National Center for Biotechnology Development, with the deposit number CGMCC No. 33326, the deposit date being January 8, 2025, and the deposit address being No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing; The Lactobacillus plantarum T80 is deposited in the General Microbiological Center of the China National Center for Biotechnology Development, with the deposit number CGMCC No. 33328, the deposit date being January 7, 2025, and the deposit address being No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

2. The compound microbial powder according to claim 1, characterized in that, In the composite microbial powder, the total effective viable count of Bacillus velezensis QCS-426, Bacillus sp. H68 and Lactobacillus plantarum T80 is not less than 8.5-9.5×10 10 cfu / g; The ratio of the viable count of the effective bacteria of the Bacillus velezensis QCS-426, the Bacillus sp. H68 and the Lactobacillus plantarum T80 is (3-5):(3-5):(90-95).

3. A method for preparing the composite microbial powder as described in claim 1 or 2, characterized in that, It includes the following steps: Activate the Bacillus velezensis QCS-426 and the Bacillus sp. H68 respectively, conduct seed culture and fermentation expansion culture using LB liquid medium, centrifuge the fermentation broth, collect the precipitate, add skimmed milk powder with a mass fraction of 5-10% and mannitol with a mass fraction of 5-10%, and conduct vacuum freeze-drying to obtain the bacterial powder of the Bacillus velezensis QCS-426 and the bacterial powder of the Bacillus sp. H68; Activate the Lactobacillus plantarum T80, conduct seed culture and fermentation expansion culture using MRS liquid medium, centrifuge the fermentation broth, collect the precipitate, add skimmed milk powder with a mass fraction of 5-10% and mannitol with a mass fraction of 5-10%, and conduct vacuum freeze-drying to obtain the bacterial powder of the Lactobacillus plantarum T80; Weigh 3-5 parts by weight of the bacterial powder of the Bacillus velezensis QCS-426, 3-5 parts by weight of the bacterial powder of the Bacillus sp. H68 and 90-95 parts by weight of the bacterial powder of the Lactobacillus plantarum T80, and mix them evenly to obtain the composite microbial bacterial powder.

4. The preparation method according to claim 3, characterized in that, The viable count of the Bacillus velezensis QCS-426 bacterial powder is 8.5 - 9.5×10 10 cfu / g; the viable count of the Bacillus sp. H68 bacterial powder is 8.5 - 9.5×10 10 cfu / g; the viable count of the Lactobacillus plantarum T80 bacterial powder is 8.5 - 9.5×10 10 cfu / g.

5. A compound microbial inoculum, characterized in that, It includes the composite microbial bacterial powder described in claim 1.

6. The composite microbial inoculum according to claim 5, characterized in that, By weight, it includes the following components: 0.5-1.5 parts of the composite microbial bacterial powder, 19-21 parts of fish meal, 34-36 parts of soybean meal and 41.5-46.5 parts of high-gluten flour.

7. Use of the composite microbial bacterial powder described in claim 1 or 2 or the composite microbial agent described in claim 5 or 6 in the preparation of aquatic feed.

8. An aquatic feed, characterized in that, It includes the composite microbial agent described in claim 5 or 6.

9. The aquatic feed according to claim 8, characterized in that, It also includes a basic feed; The mass ratio of the composite microbial agent to the basic feed is 1:2000.

10. A method for cultivating aquatic products, characterized in that, It includes the following steps: Put the compound microbial powder described in claim 1 or 2 and / or the compound microbial agent described in claim 5 or 6 into the aquaculture area; And / or, feed the aquatic feed described in claim 8 or 9.

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