A composite fermentation composition, and a preparation method and application thereof

Abstract

The present application relates to a protein feed containing a composite fermentation composition, and belongs to the technical field of microbial fermentation and feed.The protein feed comprises fermentation strains and fermentation substrates; the fermentation strains comprise Rhodopseudomonas palustris with a preservation number of CGMCC NO.17021 and Candida glabrata with a preservation number of CCTCC NO:M2015664; and the fermentation substrates comprise cottonseed meal powder, rapeseed meal powder, distiller's grains powder and citrus dreg powder.The protein feed containing the composite fermentation composition has a high feed utilization rate and can improve the immunity of the animals fed with the protein feed.

Description

Technical Field

[0001] This invention relates to the field of microbial fermentation and feed technology, and in particular to a compound fermentation composition, its preparation method, and its application. Background Technology

[0002] With the intensive development of livestock farming, the demand for feed that is high in protein, highly nutritious, and promotes health is becoming increasingly urgent. Conventional protein feed ingredients such as soybean meal and fishmeal, while having high protein content, suffer from problems such as large price fluctuations, the presence of anti-nutritional factors in some products, and amino acid imbalances, directly affecting animal digestion, absorption, and growth performance. Furthermore, in modern farming practices, animals often face various stresses, leading to decreased immunity and increased susceptibility to disease. Traditional feeds have limited effectiveness in actively regulating animal immune function. Therefore, developing novel protein feeds or feed additives that are efficiently utilized, have high nutritional value, and can enhance animal immunity has become an important research direction in this field.

[0003] Microbial fermentation technology is considered an effective means of improving feed quality. Fermenting agricultural byproducts or conventional feed ingredients with specific microbial strains can degrade anti-nutritional factors such as cellulose and phytic acid, producing beneficial substances such as small peptides, organic acids, enzymes, and vitamins, thereby improving feed digestibility and nutritional value. Currently, there are reports on the use of yeast, lactic acid bacteria, and Bacillus for single or mixed fermentation in feed production. However, existing technologies still have many shortcomings. First, many fermentation processes use relatively common microbial strains, or the combination of strains lacks clear evidence of synergistic effects, resulting in fermentation products with limited functionality and insignificant overall improvement in promoting growth and enhancing immunity. Second, the selection of fermentation substrates is often limited to single or a few raw materials, failing to fully consider the complementarity and synergistic fermentation potential of different raw material nutrients, thus limiting the diversity and abundance of bioactive substances in the final product. Furthermore, the optimization of fermentation process parameters (such as strain ratio, substrate ratio, temperature, pH, and light) is not systematic enough, and these parameters significantly affect the metabolic pathways and product composition of microorganisms; unsuitable process conditions cannot fully realize the potential of the strains and substrates.

[0004] Specifically, while research has explored the co-fermentation of photosynthetic bacteria and yeast, the following problems typically exist: the strains used may not be optimally selected for feed fermentation characteristics, resulting in insufficient adaptability and metabolic activity; the ratio between strains is not optimized, potentially leading to competitive inhibition rather than synergistic symbiosis; substrate selection fails to provide the best co-fermentation environment for specific strain combinations; and process conditions (such as light intensity, crucial for photosynthetic bacteria) are not precisely controlled. These factors lead to unstable quality and limited functional benefits of existing fermented products, making it difficult to meet market demand for high-efficiency, multifunctional feed additives. Therefore, there is an urgent need to develop a co-fermentation composition based on specific functional strains, optimized substrate formulation, and refined fermentation processes, enabling the stable and efficient production of feed additives with both high feed utilization and significant immune-enhancing functions, thereby overcoming the shortcomings of existing technologies. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art and provide a compound fermentation composition, its preparation method and application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a compound fermentation composition, the composition comprising a fermentation strain and a fermentation substrate; wherein the fermentation strain is a compound strain, the compound strain comprising *Rhodopseudomonas palustris* with accession number CGMCCNO.17021 and *Candida glabrata* with accession number CCTCCNO:M2015664, with a live cell ratio of 1:1-3; the fermentation substrate comprises at least one of cottonseed meal, rapeseed meal, distiller's grains, and citrus pomace powder.

[0007] Preferably, the preparation method of the fermentation composition includes the following steps: S1: Mix cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder evenly to obtain a mixed powder; S2: Use deionized water to prepare the mixed powder into a mixed solution, wherein the ratio of mixed powder to deionized water is 1:10-15 g / mL; S3: After sterilizing the mixture, inoculate it with a compound microbial strain and ferment for 24-32 hours; after fermentation, sterilize and filter to obtain the fermentation filtrate, and freeze-dry the fermentation filtrate to obtain the fermentation composition powder.

[0008] Preferably, the mass ratio of cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder is 1:4-6:8-10:3-7.

[0009] Preferably, the total viable count of the compound microbial strain is 1×10⁻⁶. 8 -1×10 10 CFU / g; the inoculation amount of the compound strain is 3-5 wt%.

[0010] Preferably, in step S3, the fermentation temperature is 28-30℃; the initial fermentation pH is 6.0-6.5; the light intensity is 3000-4000 LX; the stirring speed is 200-400 r / min; and the dissolved oxygen content in the fermentation broth is 0.5-1 mg / L.

[0011] The fermentation composition prepared by the present invention using specific components and specific preparation methods has the advantages of high nutritional value and oxidative stability.

[0012] In a second aspect, the present invention provides the use of the composition described in the first aspect in the preparation of high-protein feed.

[0013] Thirdly, the present invention provides a high-protein feed, characterized in that the feed comprises the compound fermentation composition described in the first aspect.

[0014] Preferably, the high-protein feed further includes at least one of soybean meal, fish meal, grain meal, and corn meal.

[0015] Fourthly, the present invention provides the use of the composition described in the first aspect in the preparation of poultry and livestock feed.

[0016] Fifthly, the present invention provides the use of the composition described in the first aspect in the preparation of aquatic feed.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The composite fermentation composition, its preparation method, and its application provided by this invention have the following outstanding beneficial effects, and these effects stem from the synergistic effect between the various components and the process: The core beneficial effect of this invention lies in the significant synergistic effect achieved through the synergistic combination of specific functional strains, the optimized combination of specific substrate systems, and the precise control of process parameters. This results in the preparation of a high-quality fermentation composition that can systematically improve feed utilization efficiency and immune function. The synergistic effect mechanism is mainly reflected in the following three aspects: First, at the microbial level, *Rhodopseudomonas palustris* (CGMCC NO. 17021) and *Candida glabrata* (CCTCC NO: M2015664) exhibit a unique metabolic complementarity and symbiotic synergy. *Rhodopseudomonas palustris*, as a photosynthetic bacterium, can utilize light energy for photosynthesis, synthesizing vitamins, coenzymes, and various bioactive substances, and can effectively utilize small organic molecules; *Candida glabrata*, on the other hand, possesses strong protease activity and vigorous protein metabolism. When the two are co-fermented at the viable cell ratio (1:1-3) defined in this invention, it is not a simple functional superposition, but rather the formation of a highly efficient symbiotic system. The metabolic activities of yeast can provide necessary growth factors or specific metabolic precursors for the growth of photosynthetic bacteria, while the microenvironment created by photosynthetic bacteria through their unique metabolic pathways (such as redox potential, dissolved oxygen, and metabolite profiles) can promote specific beneficial metabolic fluxes in yeast. This close, mutually beneficial symbiotic relationship significantly enhances the overall metabolic activity and stability of the entire fermentation system, thereby synergistically promoting the synthesis and accumulation of richer and more balanced functional metabolites (such as easily digestible small peptides, free amino acids, vitamins, digestive enzymes, antioxidants, and immunopolysaccharides).

[0018] Secondly, at the substrate level, four raw materials—cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder—are blended in a specific mass ratio (1:4-6:8-10:3-7) to form a composite fermentation substrate with optimized nutrition and physical structure. This specific ratio ensures a balanced and complementary supply of carbon, nitrogen, minerals, vitamins, and structural fibers. The composition and content of anti-nutritional factors (such as gossypol and glucosinolates) vary among the different raw materials; under the synergistic degradation of the composite microbial community, these factors can mutually promote their decomposition and elimination. Simultaneously, the diverse substrate provides a wide and balanced range of metabolic precursors for the aforementioned specific composite microbial community, guiding the community to synthesize more diverse and beneficial secondary metabolites. The suitable particle size and water-holding capacity of this substrate also help maintain a good physical structure and mass transfer efficiency in the fermentation system, thus providing the optimal material basis for the efficient synergistic metabolism of the microbial community.

[0019] Finally, the synergistic potential between the specific bacterial strains and the specific substrates is fully activated and maximized under the process conditions defined in this invention. Combined with suitable fermentation temperature, pH, and stirring speed, a microenvironment optimally suited to the metabolic activities of the specific complex microbial community is constructed, enabling the entire fermentation process to proceed in a targeted and efficient manner.

[0020] In summary, the composite fermentation composition of this invention is not a mechanical combination of components and processes, but rather a system-level optimization achieved through an organic whole comprised of "specific functional microbial strain compatibility—specific nutrient substrate combination—specific process activation." This synergistic system can efficiently transform substrates, significantly reduce anti-nutritional factor levels, and enrich various active substances that promote growth and health. When the final product is applied to feed, it can synergistically exert multiple effects through multiple pathways, such as providing balanced nutrition, improving intestinal health, and enhancing specific and non-specific immune responses, thereby exhibiting a significant and stable comprehensive gain effect in improving feed conversion rate and enhancing animal disease resistance, surpassing that of single-strain fermentation, ordinary mixed fermentation, or simple raw material mixing. Detailed Implementation

[0021] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0022] The sources of some of the raw materials used in this invention are as follows: Rhodopseudomonas palustris: Accession number CGMCCNO.17021; Candida glabrata: preservation number CCTCCNO: M2015664; Cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder were purchased from Shijiazhuang Mianfan Trading Co., Ltd.

[0023] All other raw materials, equipment, test reagents, and test equipment were commercially available.

[0024] Compound fermentation composition 1 It is prepared by the following method: S1: Mix cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder evenly to obtain a mixed powder; S2: Use deionized water to prepare the mixed powder into a mixed solution, wherein the ratio of mixed powder to deionized water is 1:13 g / mL; S3: After sterilizing the mixture, inoculate it with a compound microbial strain and ferment for 28 hours; after fermentation, sterilize and filter to obtain fermentation filtrate, and freeze-dry the fermentation filtrate to obtain fermentation composition powder. The compound microbial strain consists of Rhodopseudomonas palustris with a viable count ratio of 1:2, with accession number CGMCCNO.17021 and Candida glabrata with accession number CCTCCNO:M2015664; The mass ratio of cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder is 1:5:9:5.

[0025] The total viable count of the compound microbial strain is 1×10⁻⁶. 9 CFU / g; the inoculation amount of the compound strain is 4wt%.

[0026] In step S3, the fermentation temperature is 29℃; the initial fermentation pH is 6.3; the light intensity is 3500 LX; the stirring speed is 300 r / min; and the dissolved oxygen content in the fermentation broth is 0.8 mg / L.

[0027] Compound fermentation composition 2 It is prepared by the following method: S1: Mix cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder evenly to obtain a mixed powder; S2: Use deionized water to prepare the mixed powder into a mixed solution, wherein the ratio of mixed powder to deionized water is 1:10 g / mL; S3: After sterilizing the mixture, inoculate it with a compound microbial strain and ferment for 32 hours; after fermentation, sterilize and filter to obtain fermentation filtrate, and freeze-dry the fermentation filtrate to obtain fermentation composition powder. The compound microbial strain consists of Rhodopseudomonas palustris with a viable count ratio of 1:1, with accession number CGMCCNO.17021, and Candida glabrata with accession number CCTCCNO:M2015664. The mass ratio of cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder is 1:4:8:3.

[0028] The total viable count of the compound microbial strain is 1×10⁻⁶. 8 CFU / g; the inoculation amount of the compound strain is 3wt%.

[0029] In step S3, the fermentation temperature is 28℃; the initial fermentation pH is 6.0; the light intensity is 3000 LX; the stirring speed is 200 r / min; and the dissolved oxygen content in the fermentation broth is 0.5 mg / L.

[0030] Compound fermentation composition 3 It is prepared by the following method: S1: Mix cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder evenly to obtain a mixed powder; S2: Use deionized water to prepare the mixed powder into a mixed solution, wherein the ratio of mixed powder to deionized water is 1:15 g / mL; S3: After sterilizing the mixture, inoculate it with a compound microbial strain and ferment for 24 hours; after fermentation, sterilize and filter to obtain fermentation filtrate, and freeze-dry the fermentation filtrate to obtain fermentation composition powder. The compound microbial strain consists of *Rhodopseudomonas palustris* with a viable count ratio of 1:3 and preservation number CGMCCNO.17021 and *Candida glabrata* with preservation number CCTCCNO:M2015664. The mass ratio of cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder in the mixed powder is 1:6:10:7.

[0031] The total viable count of the compound microbial strain is 1×10⁻⁶. 10 CFU / g; the inoculation amount of the compound strain is 5wt%.

[0032] In step S3, the fermentation temperature is 30℃; the initial fermentation pH is 6.5; the light intensity is 4000 LX; the stirring speed is 400 r / min; and the dissolved oxygen content in the fermentation broth is 1 mg / L.

[0033] Compound Fermentation Composition A The only difference between this composition and composition 1 is that the compound bacterial strain used in composition A is Rhodopseudomonas palustris with preservation number CGMCCNO.17021. All other steps, raw materials, and parameters are the same as those in composition 1.

[0034] Compound Fermentation Composition B The only difference between Composition B and Composition 1 is that Composition B uses Candida glabrata with preservation number CCTCCNO: M2015664 as the compound strain. All other steps, raw materials, and parameters are the same as those of Composition 1.

[0035] Compound fermentation composition C The only difference between composition C and composition 1 is that composition C uses Rhodopseudomonas palustris with accession number CGMCCNO.1.2180 instead of Rhodopseudomonas palustris with accession number CGMCCNO.17021. All other steps, raw materials, and parameters are the same as those of composition 1.

[0036] Compound Fermentation Composition D The only difference between composition D and composition 1 is that composition D uses Candida glabrata with accession number CGMCCNO.12449 instead of Candida glabrata with accession number CCTCCNO:M2015664. All other steps, raw materials, and parameters are the same as those in composition 1.

[0037] Compound fermentation composition E The only difference from composition 1 is that the complex microbial strain of composition E consists of Rhodopseudomonas palustris with a viable count ratio of 2:1 and Candida glabrata with a preservation number of CGMCCNO.17021 and a viable count ratio of CCTCCNO:M2015664; the remaining steps, raw materials and parameters are the same as those of composition 1.

[0038] Compound fermentation composition F The only difference between composition F and composition 1 is that the mixed powder of composition F lacks cottonseed meal powder and is composed of rapeseed meal powder, distiller's grains powder and citrus pomace powder in a mass ratio of 5:9:5. The other steps, raw materials and parameters are the same as those of composition 1.

[0039] Compound Fermentation Composition G The only difference between composition G and composition 1 is that composition G lacks rapeseed meal powder and is composed of cottonseed meal powder, distillers' grains powder, and citrus pomace powder in a mass ratio of 1:9:5. The remaining steps, raw materials, and parameters are the same as those of composition 1.

[0040] Compound fermentation composition H The only difference between composition H and composition 1 is that the mixed powder of composition H lacks distillers' grains powder and is composed of cottonseed meal powder, rapeseed meal powder and citrus pomace powder in a mass ratio of 1:5:5. The other steps, raw materials and parameters are the same as those of composition 1.

[0041] Compound Fermentation Composition I The only difference between Composition I and Composition 1 is that Composition I lacks citrus pomace powder and is composed of cottonseed meal powder, rapeseed meal powder, and distiller's grains powder in a mass ratio of 1:5:9. The remaining steps, raw materials, and parameters are the same as those of Composition 1.

[0042] Compound fermentation composition J The only difference between composition J and composition 1 is that the mixed powder of composition J consists of cottonseed meal powder, rapeseed meal powder, distiller's grains powder and citrus pomace powder in a mass ratio of 1:7:5:2. The remaining steps, raw materials and parameters are the same as those of composition 1.

[0043] Compound fermentation composition K The only difference between composition K and composition 1 is that composition K uses YPD culture medium powder to replace the mixed powder by the same mass, while the other steps, raw materials, and parameters are the same as those in composition 1.

[0044] Compound fermentation composition L The only difference between composition L and composition 1 is that composition L lacks mixed culture fermentation. The specific steps are as follows: S1: Mix cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder evenly to obtain a mixed powder; S2: Use deionized water to prepare the mixed powder into a mixed solution, wherein the ratio of mixed powder to deionized water is 1:13 g / mL; S3: Sterilize the mixture and then let it stand for 28 hours; after standing, sterilize and filter to obtain the filtrate, and freeze-dry the filtrate to obtain the composite powder; The mass ratio of cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder is 1:5:9:5.

[0045] Efficacy verification Test Example 1: Verification of the Physicochemical Properties of Fermentation Compositions Test samples: compound fermentation compositions 1-3, compound fermentation composition AE; control sample: compound fermentation composition L; Detection indicators: Free gossypol degradation rate, glucosinolate degradation rate Degradation rate of free gossypol: The degradation rate relative to the compound fermentation composition L was calculated according to GB / T13086-2020 "Determination of free gossypol in feed".

[0046] Degradation rate (%) = [(Free gossypol content in compound fermentation composition L - Free gossypol content in sample) / Free gossypol content in compound fermentation composition L] × 100%.

[0047] Degradation rate of glucosinolates: Refer to GB / T13089-2020 "Determination of oxazolidinithiophene in feed".

[0048] Degradation rate (%) = [(content in compound fermentation composition L - content in sample) / content in compound fermentation composition L] × 100%.

[0049] The results are shown in Table 1.

[0050] Table 1. Verification of the physicochemical properties of the fermentation composition. sample Gossypol degradation rate (%) Degradation rate of glucosinolates (%) Compound fermentation composition 1 93.2 82.1 Compound fermentation composition 2 85.3 74.9 Compound fermentation composition 3 89.7 78.2 Compound Fermentation Composition A 72.5 45.6 Compound Fermentation Composition B 65.3 68.9 Compound fermentation composition C 71.8 44.9 Compound Fermentation Composition D 66.1 47.2 Compound fermentation composition E 78.4 60.5 Test Example 1 verified the significant effect of the present invention's technical solution in improving the nutritional quality of the product and efficiently removing specific anti-nutritional factors by measuring the free gossypol degradation rate and glucosinolate degradation rate of the compound fermentation compositions 1-3 and their comparative example AE relative to the unfermented control composition L. Experimental data showed that compositions 1-3 within the scope of the present invention performed excellently, with degradation rates of approximately 89.7% and 78.4% for free gossypol and glucosinolates, respectively. In contrast, comparative examples A and B using a single strain, or comparative examples C and D replacing them with non-specific preserved strains, or comparative example E with a changed strain ratio, all showed significant decreases in their key indicators. The comparative data fully demonstrate that the specific strain combination defined in claims 1-5 (Rhodopseudomonas palustris palustris with accession number CGMCCNO.17021 and Candida glabrata with accession number CCTCCNO:M2015664, viable count ratio 1:1-3) and the specific substrate system (cottonseed meal, rapeseed meal, distiller's grains, and citrus pomace powder, mass ratio 1:4-6:8-10:3-7) produced a significant synergistic effect under the described process.

[0051] Test Example 2: Effects of Compound Fermentation Composition on Piglet Weight and Immunity Test samples: Compound fermentation compositions 1-3, Compound fermentation composition AL; The basic daily ration is shown in Table 2 below: Table 2 Composition of the basic diet Basic Dietary Ingredients Content / wt% corn 37 puffed corn 16 soybean meal 13 fish meal 10 whey powder 9 puffed soybeans 6 glucose 2 Soybean oil 2 wheat bran 5 total 100 Healthy, 28-day-old weaned DLY piglets of similar weight were randomly divided into 16 groups of 10 piglets each. A blank control group was established (fed only the basal diet), while the other groups were fed their basal diets supplemented with 15 wt% of compound fermentation composition 1-3 and compound fermentation composition AL, respectively. The experiment lasted 42 days.

[0052] Feed utilization rate indicators: record initial weight, final weight, and feed consumption, and calculate the feed conversion ratio (kg / kg).

[0053] Immunological indicators: Blood was collected at the end of the experiment, serum was separated, and the content of immunoglobulin IgG and the concentration of inflammatory factor interleukin-6 (IL-6) in the serum were measured. The rate of change of IgG or IL-6 was calculated.

[0054] IgG change rate / % = (compound fermentation group - blank control group) / blank control group × 100%; IL-6 change rate / % = (blank control group - compound fermentation composition group) / blank control group × 100%; The specific results are shown in Table 3.

[0055] Table 3. Effects of the compound fermentation composition on immunity and feed utilization. Group Material weight ratio (kg / kg) IgG change rate / % IL-6 change rate / % Compound fermentation composition 1 1.189 24.734 32.601 Compound fermentation composition 2 1.237 24.746 31.735 Compound fermentation composition 3 1.275 23.625 30.443 Compound Fermentation Composition A 1.634* 2.909* 4.382* Compound Fermentation Composition B 1.638* 3.805* 5.948* Compound fermentation composition C 1.576* 3.962* 7.126* Compound Fermentation Composition D 1.565* 6.138* 8.484* Compound fermentation composition E 1.402* 11.428* 16.337* Compound fermentation composition F 1.553* 8.126* 12.743* Compound Fermentation Composition G 1.581* 6.407* 10.164* Compound fermentation composition H 1.521* 8.932* 12.768* Compound Fermentation Composition I 1.468* 6.923* 11.908* Compound fermentation composition J 1.374* 9.559* 14.604* Compound fermentation composition K 1.557* 5.449* 9.008* Compound fermentation composition L 1.687* 1.812* 2.704* Blank control group 1.731 0 0 Note: "*" indicates that p < 0.05 compared to compound fermentation composition 1.

[0056] The efficacy of the compound fermentation compositions was evaluated through a series of comparative experiments (compound fermentation compositions 1-3, AL, and a blank control). Data showed that the optimal embodiments of the present invention (compound fermentation compositions 1-3) were significantly superior to the control groups in improving the growth performance and immunity of weaned piglets. Specifically, compound fermentation composition 1 performed best, with its overall effect significantly superior to compound fermentation compositions A (Rhodopseudomonas palustris only) and B (Candida glabrata only), which used only single-strain bacteria, and also superior to compound fermentation compositions C and D, which used non-specific preservation number bacteria. This demonstrates that Rhodopseudomonas palustris with preservation number CGMCCNO.17021 and Candida glabrata with preservation number CCTCCNO:M2015664, when combined in a specific ratio (1:1-3), exhibit a synergistic effect. Meanwhile, the efficacy of compound fermentation compositions F, G, H, and I, which lack any one of the substrates (cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder), or compound fermentation composition J, whose substrate ratio deviates from the scope of the claims, all showed a significant decrease. This indicates that the four substrates, in a specific mass ratio (1:4-6:8-10:3-7), together constitute the optimal fermentation substrate suitable for the metabolism of the compound microorganisms and the production of beneficial active substances. Furthermore, using conventional culture media to replace the specific substrate mixture (compound fermentation composition K) or not fermenting (compound fermentation composition L) also resulted in inferior effects compared to the compound fermentation compositions 1-3 of the present invention, further confirming that the integration of specific microorganisms, specific substrates, and specific process parameters has a decisive influence on the efficacy of the final product. The underlying mechanism may be that specific bacterial combinations can more effectively degrade anti-nutritional factors in substrates and synthesize peptides, organic acids, vitamins and unknown growth factors through synergistic metabolism. At the same time, the optimized substrate ratio provides a balanced source of carbon and nitrogen and trace elements for the growth of the bacterial community. The resulting fermentation composition is rich in prebiotics, probiotics and immune-enhancing substances, thereby achieving the comprehensive effect of improving feed utilization and regulating the body's immunity (increasing IgG and reducing the pro-inflammatory factor IL-6).

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A compound fermentation composition, characterized in that, The composition comprises a fermentation strain and a fermentation substrate; wherein the fermentation strain is a compound strain, which includes *Rhodopseudomonas palustris* with accession number CGMCCNO.17021 and *Candida glabrata* with accession number CCTCCNO:M2015664, with a live cell ratio of 1:1-3; the fermentation substrate includes at least one of cottonseed meal, rapeseed meal, distiller's grains, and citrus pomace powder.

2. The composition according to claim 1, characterized in that, The preparation method of the fermentation composition includes the following steps: S1: Mix cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder evenly to obtain a mixed powder; S2: Use deionized water to prepare the mixed powder into a mixed solution, wherein the ratio of mixed powder to deionized water is 1:10-15 g / mL; S3: After sterilizing the mixture, inoculate it with a compound microbial strain and ferment for 24-32 hours; after fermentation, sterilize and filter to obtain the fermentation filtrate, and freeze-dry the fermentation filtrate to obtain the fermentation composition powder.

3. The composition according to claim 2, characterized in that, The mass ratio of cottonseed meal powder, rapeseed meal powder, distiller's grains powder, and citrus pomace powder is 1:4-6:8-10:3-7.

4. The composition according to claim 2, characterized in that, The total viable count of the compound microbial strain is 1×10⁻⁶. 8 -1×10 10 CFU / g; the inoculation amount of the compound strain is 3-5 wt%.

5. The composition according to claim 2, characterized in that, In step S3, the fermentation temperature is 28-30℃; the initial fermentation pH is 6.0-6.5; the light intensity is 3000-4000 LX; the stirring speed is 200-400 r / min; and the dissolved oxygen content in the fermentation broth is 0.5-1 mg / L.

6. The use of the composition according to any one of claims 1-5 in the preparation of high-protein feed.

7. A high-protein feed, characterized in that, The feed comprises the compound fermentation composition according to any one of claims 1-5.

8. The feed as described in claim 7, characterized in that, The feed also includes at least one of soybean meal, fish meal, bone meal, and corn meal.

9. The use of the composition according to any one of claims 1-5 in the preparation of poultry and livestock feed.

10. The use of the composition according to any one of claims 1-5 in the preparation of aquatic feed.