Fermentation process for preparing organic chelated calcium feed additive from inorganic calcium by microbial conversion method

Abstract

The invention relates to the technical field of feed additive preparation, and discloses a fermentation process for preparing an organic chelated calcium feed additive from inorganic calcium by a microbial conversion method, and the process comprises the following steps: mixing and crushing an inorganic calcium source, a carbon and nitrogen source feed and auxiliary materials to prepare a solid fermentation base material; adding activated composite transformed strain inoculation liquid and adjusting the total moisture content; carrying out aerobic fermentation on the material, and carrying out coordination chelation reaction on organic acid, amino acid and small molecule peptide generated by microbial metabolism and dissociated inorganic calcium to convert into water-soluble organic calcium; and after fermentation, drying with low-temperature hot air, and crushing to obtain an organic calcium product. According to the method, a multi-strain synergistic fermentation system is adopted, acid production, substrate enzymolysis and calcium ion chelation are synchronously completed in the same environment, the conversion efficiency of insoluble inorganic calcium is improved, chemical reagent residues are avoided, and the activity of probiotics and biological metabolic enzymes in the system is effectively reserved.

Description

Technical Field

[0001] This invention relates to the field of feed additive preparation technology, specifically to a fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation. Background Technology

[0002] In animal feed processing, calcium is an essential nutrient for bone development and maintaining physiological functions in livestock and poultry. Currently, inorganic calcium sources such as limestone powder, shell powder, or dicalcium phosphate are commonly added to feed to supplement calcium. Although these inorganic mineral calcium sources are inexpensive to obtain, their solubility in the animal's intestines is limited, resulting in low absorption and utilization rates by the body. Large amounts of unabsorbed inorganic calcium increase the burden on the animal's gastrointestinal tract and are excreted in feces, leading to resource waste.

[0003] To improve calcium absorption, the industry typically uses chemical synthesis to prepare organic acid calcium or amino acid chelated calcium. However, this chemical synthesis process requires the consumption of acid and alkali reagents, resulting in high overall production costs. Furthermore, chemical residues are often left in the system after the reaction, which not only reduces the safety of feed additives but also puts pressure on environmental wastewater treatment during the production process.

[0004] In recent years, the conversion of inorganic calcium using microbial fermentation has gradually become a research direction to replace chemical synthesis. While bio-fermentation offers mild reaction conditions, existing fermentation processes often rely on a single microbial species. The metabolic pathways of a single species are relatively limited, making it impossible to simultaneously and efficiently complete the processes of acid production and dissociation of inorganic calcium, as well as the secretion of enzymes to degrade nitrogen source substrates to provide sufficient amino acid ligands within the same fermentation system. This results in insufficient overall conversion efficiency of poorly soluble inorganic calcium to water-soluble organic calcium within the fermentation system, leading to low chelation rates of the product. Therefore, there is a need in this field to develop a fermentation process that can overcome the metabolic limitations of single-species fermentation and improve the bioconversion efficiency of inorganic calcium. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a fermentation process for preparing organic chelated calcium feed additives from inorganic calcium through microbial transformation. This process solves the problems of low absorption and utilization rates of inorganic calcium, high costs and easy residues of chemically synthesized organic calcium, and insufficient efficiency of single-strain fermentation for inorganic calcium conversion.

[0006] To address the aforementioned problems, this invention provides a fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation, employing the following technical solution:

[0007] The fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation includes the following steps:

[0008] Weigh out the raw materials containing inorganic calcium source, carbon source feed, nitrogen source feed and auxiliary materials, mix the raw materials evenly and crush and sieve them to obtain solid fermentation substrate;

[0009] Then, take the pre-prepared compound transformation inoculum solution and use it at 0.8%-1.5% of the total dry weight of the solid fermentation substrate. Disperse the compound transformation inoculum solution in sterile clean water, and then spray the dispersed inoculum solution directly into the solid fermentation substrate. Adjust the overall moisture content of the solid fermentation substrate and mix it thoroughly while spraying and stirring to obtain the inoculated material.

[0010] Next, the inoculated material is spread out in the fermentation device for aerobic fermentation, producing organic small molecule metabolites, which undergo complexation and chelation reactions with the inorganic calcium in the inorganic calcium source, converting the inorganic calcium into water-soluble organic calcium, and obtaining the fermented material.

[0011] After fermentation, the fermented material is transferred to a drying device and dried and dehydrated under low-temperature hot air conditions. Finally, it is crushed, sieved and packaged to obtain organic calcium products.

[0012] By adopting the above technical solution, solid-state aerobic fermentation is carried out using a multi-strain synergistic system, which simultaneously completes the processes of acid production, enzymatic hydrolysis, and inorganic calcium chelation in the same fermentation environment. Therefore, it is possible to directly convert insoluble inorganic calcium into water-soluble organic calcium.

[0013] The specific reaction mechanism can be mainly divided into several interrelated processes: organic acid synthesis and calcium ion dissociation, protein enzymatic hydrolysis, and coordination chelation. During aerobic fermentation, microorganisms utilize carbon sources to metabolize organic acids such as lactic acid and citric acid, leading to a decrease in the system's pH value. This promotes the dissociation of insoluble inorganic calcium sources into free calcium ions. The relevant reaction processes are as follows:

[0014] CaCO3+2C3H6O3→Ca(C3H5O3)2+H2O+CO2↑

[0015] 3CaCO3+2C6H8O7→Ca3(C6H5O7)2+3H2O+3CO2↑

[0016] During acid production, microbial fermentation secretes protease systems that degrade large protein molecules in the nitrogen-rich feed into free amino acids and small peptides, providing necessary organic ligands for subsequent chelation reactions. As free calcium ions and organic ligands are continuously generated, they undergo coordination reactions to form stable amino acid chelated calcium with a cyclic structure. During this process, the amino and carboxyl groups of the amino acid molecules act as electron ligands, binding with calcium ions.

[0017] Ca 2++2NH2-CH(R)-COOH→Ca(NH2-CH(R)-COO)2+2H +

[0018] This technical solution avoids the residual risks associated with the use of acid and alkali reagents in chemical synthesis methods, and achieves in-situ conversion of inorganic mineral sources into bio-organic calcium under mild fermentation conditions.

[0019] Preferably, the raw materials, by weight, include: 20-30 parts of inorganic calcium source; 40-55 parts of carbon source feed; 10-18 parts of nitrogen source feed; and 3-8 parts of auxiliary materials.

[0020] Preferably, the raw materials are as follows: the inorganic calcium source is one or more of stone powder, shell powder, dicalcium phosphate, and bone meal; the carbon source feed is one or more of corn flour, wheat bran, and rice bran; the nitrogen source feed is one or more of soybean meal, corn steep liquor powder, and yeast powder; and the auxiliary materials are brown sugar and inorganic salt buffer, wherein the inorganic salt buffer is a mixture of potassium dihydrogen phosphate and disodium hydrogen phosphate in a weight ratio of 1:1.

[0021] By adopting the above technical solution, the combination of carbon and nitrogen sources in a specific weight ratio provides sufficient nutrients for the early reproduction and growth of microorganisms. The addition of an inorganic salt buffer composed of potassium dihydrogen phosphate and disodium hydrogen phosphate maintains osmotic pressure balance in the early stages of fermentation and establishes an initial buffer system. This prevents a rapid drop in pH due to excessively rapid acid production in the early stages of fermentation, thus preventing inhibition of microbial community growth and ensuring continued acid production and dissociation of inorganic calcium.

[0022] Preferably, the inoculum solution of the compound transformation strain is prepared by activating the dry powder of the compound transformation strain composition with a brown sugar aqueous solution. The dry powder of the compound transformation strain composition is composed of a mixture of live bacterial powders of each single strain in parts by weight, including: 25-35 parts of Lactobacillus plantarum; 15-25 parts of Lactobacillus fermentum; 10-15 parts of Aspergillus niger; 15-20 parts of Bacillus subtilis; and 8-12 parts of Saccharomyces cerevisiae.

[0023] Preferably, the activation preparation method of the compound transformation strain inoculum includes: mixing the live bacterial powders of each single strain to prepare a solution with a total live bacterial content of not less than 5.0 × 10⁻⁶. 9 The compound transformation strain composition dry powder (CFU / g) is added to a 5% brown sugar aqueous solution at a weight ratio of 1:10 and slowly stirred at room temperature for 1-2 hours to obtain the compound transformation strain inoculum.

[0024] By employing the above technical solution, a transformation system using a complex combination of multiple microbial communities, including *Lactobacillus plantarum*, is utilized. *Lactobacillus plantarum* and *Lactobacillus fermentum* ferment to produce lactic acid, while *Aspergillus niger* and *Bacillus subtilis* secrete corresponding amylases and proteases to degrade carbon and nitrogen sources in the substrate for use by lactic acid bacteria. *Aspergillus niger* also metabolizes to produce citric acid. *Saccharomyces cerevisiae* primarily consumes free oxygen in the system, thereby promoting the metabolic process of lactic acid bacteria and synthesizing trace substances such as vitamins. The various strains work synergistically in spatial colonization and substrate utilization, simultaneously generating lactic acid, citric acid, amino acids, and other multi-ligand substances, effectively improving the conversion efficiency of calcium ions. Activation with a brown sugar solution before inoculation restores the metabolic activity of the dormant dry powder strains, shortening the lag period for fermentation initiation.

[0025] Preferably, the sieve mesh size for the crushing and sieving process is 20-40 mesh; and the overall moisture content of the solid fermentation substrate is adjusted to 55%-60%.

[0026] Preferably, the conditions for aerobic fermentation are: controlling the fermentation temperature at 30-37℃, carrying out aerobic fermentation for 48-72 hours, and maintaining an intermittent oxygen supply environment through intermittent turning or intermittent ventilation.

[0027] Preferably, at the end of aerobic fermentation, the pH value of the fermented material is 4.0-5.0.

[0028] Preferably, the organic small molecule metabolites include one or more of lactic acid, citric acid, amino acids, and small molecule peptides.

[0029] Preferably, the drying and dehydration conditions under low temperature hot air conditions are: hot air drying at 40-55℃ until the moisture content of the fermented material is 6%-10%.

[0030] By adopting the above technical solution, the limited particle size of the fermentation substrate (20-40 mesh) and the overall moisture content (55%-60%) ensure that the material maintains an appropriate porous structure, facilitating the entry of bacteria into the material for degradation reactions. The fermentation temperature is controlled at 30-37℃, perfectly meeting the suitable temperature range for acid and enzyme production by multiple bacterial groups. Simultaneously, the intermittent oxygen supply environment satisfies the oxygen requirements of aerobic Aspergillus niger and Bacillus subtilis, while also considering the acid-producing environment requirements of lactic acid bacteria. The final pH value is used as a process control parameter; reaching 4.0-5.0 indicates that inorganic calcium has been largely consumed by newly generated organic acids, forming a buffer system. Ending fermentation at this point avoids excessive substrate consumption. The drying stage uses hot air at 40-55℃ to remove moisture, preserving the physicochemical stability of the bio-organic calcium while maintaining the activity of probiotics and enzymes in the material, ensuring the practical application effect of the feed additive.

[0031] This invention provides a fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation. It offers the following advantages:

[0032] 1. This invention employs a multi-microbial complex conversion system for solid-state fermentation. It utilizes acid-producing bacteria to produce organic acids and enzyme-producing bacteria to secrete corresponding enzymes to degrade the substrate. Under this synergistic effect, carbon and nitrogen sources are degraded into free amino acids and small peptides, etc. The decrease in pH of the system promotes the dissociation of insoluble inorganic calcium sources into free calcium ions. The acid production, substrate degradation, and coordination chelation processes are completed simultaneously in the same fermentation environment, enabling inorganic calcium to be converted in situ into water-soluble amino acid chelated calcium, thereby improving the overall conversion efficiency of inorganic mineral sources.

[0033] 2. The fermentation raw materials of this invention contain an inorganic salt buffer, and the pH of the material is used as a monitoring indicator to determine the end of fermentation during the aerobic fermentation stage. The construction of the initial buffer system maintains the osmotic pressure balance in the early stage of fermentation, avoids the rapid acid production during fermentation causing a sudden drop in environmental acidity, and prevents the metabolic proliferation of the microbial community from being inhibited. Using pH change as the endpoint determination criterion, the process node of inorganic calcium dissociation and the formation of stable chelates with organic acids and amino acids can be accurately grasped, avoiding excessive consumption of substrate and ensuring the continuity of the process and the stability of production batches.

[0034] 3. The post-processing step of this invention uses low-temperature hot air conditions to dry and dehydrate the fermented materials. This gentle drying process not only removes excess moisture from the system to meet the conventional storage and packaging requirements of the product, but also maintains the stability of the physicochemical structure of the newly generated bio-organic calcium. On the other hand, the low-temperature environment effectively avoids the damage of heat-sensitive components to heat processing, preserves the survival rate of the original beneficial bacteria and the activity of bio-metabolic enzymes in the fermented materials, and ensures the nutritional and probiotic functions of the final feed additive. Attached Figure Description

[0035] Figure 1 The diagram shows the dynamic changes of the core metabolites and pH value during the fermentation process of this invention. (a) is a diagram showing the dynamic changes of the pH value of the system, (b) is a diagram showing the dynamic changes of lactic acid production, (c) is a diagram showing the dynamic changes of citric acid production, and (d) is a diagram showing the dynamic changes of free amino acid production.

[0036] Figure 2 The graphs shown are dynamic tracking test diagrams of the in-situ chelation transformation of inorganic calcium in this invention, wherein (a) is a dynamic change graph of the content of water-soluble and insoluble calcium, and (b) is a dynamic change graph of the conversion rate of inorganic calcium.

[0037] Figure 3The following is a comprehensive evaluation test chart of the core physicochemical and microecological indicators of this invention. Among them, (a) is the equivalent pH value level chart of each batch of finished products, (b) is the comparison chart of inorganic calcium conversion rate and water-soluble calcium content, and (c) is the comparison chart of live bacteria in the finished products.

[0038] Figure 4 The following is an evaluation chart of the dual effects of animal absorption and intestinal microecology in this invention. (a) is a test chart of apparent digestion of calcium and tibial deposition, (b) is a test chart of the average diarrhea rate during the test period, and (c) is a test chart of the concentration of cecal core microecological flora. Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Preparation Examples 1-3:

[0041] Preparation Example 1:

[0042] This preparation example provides a method for preparing a compound transforming bacterial inoculum for the fermentation of inorganic calcium to organic calcium, including the following steps:

[0043] Each single-strain live bacterial powder was used as a raw material. 25 parts by weight of *Lactobacillus plantarum*, 15 parts by weight of *Lactobacillus fermentum*, 10 parts by weight of *Aspergillus niger*, 15 parts by weight of *Bacillus subtilis*, and 8 parts by weight of *Saccharomyces cerevisiae* were weighed and mixed evenly to obtain a composite transformation bacterial composition dry powder. The total viable bacteria content was tested to be no less than 5.0 × 10⁻⁶. 9 CFU / g. Weigh out brown sugar and dissolve it in sterile water to prepare a 5% (w / w) brown sugar aqueous solution. Take the above-mentioned compound transformation strain composition dry powder and inoculate it into the brown sugar aqueous solution at a weight ratio of 1:10. Stir slowly at room temperature for 1 hour to activate the compound transformation strain inoculum for later use.

[0044] Preparation Example 2:

[0045] This preparation example provides a method for preparing a compound transforming bacterial inoculum for the fermentation of inorganic calcium to organic calcium, including the following steps:

[0046] Each single-strain live bacterial powder was used as a raw material. 30 parts by weight of *Lactobacillus plantarum*, 20 parts by weight of *Lactobacillus fermentum*, 12 parts by weight of *Aspergillus niger*, 18 parts by weight of *Bacillus subtilis*, and 10 parts by weight of *Saccharomyces cerevisiae* were weighed and mixed evenly to obtain a composite transformation bacterial composition dry powder. The total viable bacteria content was tested to be no less than 5.0 × 10⁻⁶. 9CFU / g. Weigh out brown sugar and dissolve it in sterile water to prepare a 5% (w / w) brown sugar aqueous solution. Take the above-mentioned compound transformation strain composition dry powder and inoculate it into the brown sugar aqueous solution at a weight ratio of 1:10. Stir slowly at room temperature for 1.5 hours to activate the compound transformation strain inoculum for later use.

[0047] Preparation Example 3:

[0048] This preparation example provides a method for preparing a compound transforming bacterial inoculum for the fermentation of inorganic calcium to organic calcium, including the following steps:

[0049] Each single-strain live bacterial powder was used as a raw material. 35 parts by weight of *Lactobacillus plantarum*, 25 parts by weight of *Lactobacillus fermentum*, 15 parts by weight of *Aspergillus niger*, 20 parts by weight of *Bacillus subtilis*, and 12 parts by weight of *Saccharomyces cerevisiae* were weighed and mixed evenly to obtain a composite transformation bacterial composition dry powder. The total viable bacteria content was tested to be no less than 5.0 × 10⁻⁶. 9 CFU / g. Weigh out brown sugar and dissolve it in sterile water to prepare a 5% (w / w) brown sugar aqueous solution. Take the above-mentioned compound transformation strain composition dry powder and inoculate it into the brown sugar aqueous solution at a weight ratio of 1:10. Stir slowly at room temperature for 2 hours to activate the compound transformation strain inoculum for later use.

[0050] Examples 1-5:

[0051] Example 1:

[0052] This embodiment provides a fermentation process for preparing organic chelated calcium feed additives from inorganic calcium through microbial transformation, including the following steps:

[0053] Raw material pretreatment: Weigh 25 parts by weight of stone powder, 48 parts by weight of corn flour, 14 parts by weight of soybean meal, and 5 parts by weight of auxiliary materials (including 3 parts by weight of brown sugar and 2 parts by weight of inorganic salt buffer composed of potassium dihydrogen phosphate and disodium hydrogen phosphate in a weight ratio of 1:1). Mix the above materials evenly, crush them and pass them through a 30-mesh sieve to obtain a uniform solid fermentation substrate.

[0054] For moisture adjustment and inoculation, take the activated composite transformation strain inoculation solution prepared in Preparation Example 2, and the amount of the inoculation solution is calculated as 1.2% of the total dry weight of the solid fermentation substrate. Disperse the inoculation solution in an appropriate amount of sterile clean water, and then spray it into the solid fermentation substrate while spraying and stirring. Adjust the total moisture content of the fermentation substrate to 58% and stir thoroughly.

[0055] Aerobic fermentation involves spreading the inoculated material evenly in a fermentation device, controlling the fermentation temperature at 33°C, intermittently turning the pile to maintain an oxygen supply environment, and carrying out aerobic fermentation for 60 hours. During the fermentation process, microbial metabolism produces lactic acid, citric acid, amino acids, and small molecule peptides, which undergo complexation and chelation reactions with inorganic calcium, converting it into water-soluble organic calcium. The pH value of the material at the fermentation endpoint is 4.5.

[0056] After post-processing, the material is transferred to a drying device after fermentation and dried with low-temperature hot air at 48℃ until the moisture content of the material is 8%. The material is then crushed, sieved, and packaged to obtain a high-conversion-rate organic calcium product.

[0057] Example 2:

[0058] This embodiment provides a fermentation process for preparing organic chelated calcium feed additives from inorganic calcium through microbial transformation, including the following steps:

[0059] Raw material pretreatment: Weigh 20 parts by weight of stone powder, 40 parts by weight of corn flour, 10 parts by weight of soybean meal, and 3 parts by weight of auxiliary materials (including 2 parts by weight of brown sugar and 1 part by weight of inorganic salt buffer composed of potassium dihydrogen phosphate and disodium hydrogen phosphate in a weight ratio of 1:1). Mix the above materials evenly, crush them and pass them through a 20-mesh sieve to obtain a uniform solid fermentation substrate.

[0060] For moisture adjustment and inoculation, take the activated composite transformation strain inoculation solution prepared in Preparation Example 1, and the amount of the inoculation solution is calculated as 0.8% of the total dry weight of the solid fermentation substrate. Disperse the inoculation solution in an appropriate amount of sterile clean water, and then spray it into the solid fermentation substrate while spraying and stirring. Adjust the total moisture content of the fermentation substrate to 55% and stir thoroughly.

[0061] Aerobic fermentation involves spreading the inoculated material evenly in a fermentation device, controlling the fermentation temperature at 30°C, and intermittently ventilating to maintain an oxygen supply environment for 48 hours. During fermentation, microbial metabolism produces lactic acid, citric acid, amino acids, and small molecule peptides, which undergo complexation and chelation reactions with inorganic calcium, converting it into water-soluble organic calcium. The pH value of the material at the fermentation endpoint is 4.0.

[0062] After post-processing, the material is transferred to a drying device after fermentation and dried with low-temperature hot air at 40℃ until the moisture content of the material is 10%. The material is then crushed, sieved, and packaged to obtain a high-conversion organic calcium product.

[0063] Example 3:

[0064] This embodiment provides a fermentation process for preparing organic chelated calcium feed additives from inorganic calcium through microbial transformation, including the following steps:

[0065] Raw material pretreatment: Weigh 30 parts by weight of stone powder, 55 parts by weight of corn flour, 18 parts by weight of soybean meal, and 8 parts by weight of auxiliary materials (including 5 parts by weight of brown sugar and 3 parts by weight of inorganic salt buffer composed of potassium dihydrogen phosphate and disodium hydrogen phosphate in a weight ratio of 1:1). Mix the above materials evenly, crush them and pass them through a 40-mesh sieve to obtain a uniform solid fermentation base.

[0066] For moisture adjustment and inoculation, take the activated composite transformation strain inoculation solution prepared in Preparation Example 3, and the amount of the inoculation solution is calculated as 1.5% of the total dry weight of the solid fermentation substrate. Disperse the inoculation solution in an appropriate amount of sterile clean water, and then spray it into the solid fermentation substrate while spraying and stirring. Adjust the total moisture content of the fermentation substrate to 60% and stir thoroughly.

[0067] Aerobic fermentation involves spreading the inoculated material evenly in a fermentation device, controlling the fermentation temperature at 37°C, intermittently turning the pile to maintain an oxygen supply environment, and carrying out aerobic fermentation for 72 hours. During the fermentation process, microbial metabolism produces lactic acid, citric acid, amino acids, and small molecule peptides, which undergo complexation and chelation reactions with inorganic calcium, converting it into water-soluble organic calcium. The pH value of the material at the fermentation endpoint is 5.0.

[0068] After post-fermentation, the material is transferred to a drying device and dried with low-temperature hot air at 55°C until the moisture content of the material is 6%. The material is then crushed, sieved, and packaged to obtain a high-conversion-rate organic calcium product.

[0069] Example 4:

[0070] This embodiment provides a fermentation process for preparing organic chelated calcium feed additives from inorganic calcium through microbial transformation, including the following steps:

[0071] Raw material pretreatment: Weigh 25 parts by weight of shell powder, 48 parts by weight of wheat bran, 14 parts by weight of corn steep liquor powder, and 5 parts by weight of auxiliary materials (including 3 parts by weight of brown sugar and 2 parts by weight of inorganic salt buffer composed of potassium dihydrogen phosphate and disodium hydrogen phosphate in a weight ratio of 1:1). Mix the above materials evenly, crush them and pass them through a 30-mesh sieve to obtain a uniform solid fermentation base.

[0072] For moisture adjustment and inoculation, take the activated composite transformation strain inoculation solution prepared in Preparation Example 2, and the amount of the inoculation solution is calculated as 1.2% of the total dry weight of the solid fermentation substrate. Disperse the inoculation solution in an appropriate amount of sterile clean water, and then spray it into the solid fermentation substrate while spraying and stirring. Adjust the total moisture content of the fermentation substrate to 58% and stir thoroughly.

[0073] Aerobic fermentation involves spreading the inoculated material evenly in a fermentation device, controlling the fermentation temperature at 33°C, intermittently turning the pile to maintain an oxygen supply environment, and carrying out aerobic fermentation for 60 hours. During the fermentation process, microbial metabolism produces lactic acid, citric acid, amino acids, and small molecule peptides, which undergo complexation and chelation reactions with inorganic calcium, converting it into water-soluble organic calcium. The pH value of the material at the fermentation endpoint was measured to be 4.4.

[0074] After post-processing, the material is transferred to a drying device after fermentation and dried with low-temperature hot air at 48℃ until the moisture content of the material is 8%. The material is then crushed, sieved, and packaged to obtain a high-conversion-rate organic calcium product.

[0075] Example 5:

[0076] This embodiment provides a fermentation process for preparing organic chelated calcium feed additives from inorganic calcium through microbial transformation, including the following steps:

[0077] Raw material pretreatment: Weigh 25 parts by weight of an inorganic calcium source mixture consisting of equal weights of dicalcium phosphate and bone meal, 48 parts by weight of rice bran, 14 parts by weight of yeast powder, and 5 parts by weight of auxiliary materials (including 3 parts by weight of brown sugar and 2 parts by weight of an inorganic salt buffer consisting of potassium dihydrogen phosphate and disodium hydrogen phosphate in a weight ratio of 1:1). Mix the above materials evenly, crush them, and pass them through a 30-mesh sieve to obtain a uniform solid fermentation substrate.

[0078] For moisture adjustment and inoculation, take the activated composite transformation strain inoculation solution prepared in Preparation Example 2, and the amount of the inoculation solution is calculated as 1.2% of the total dry weight of the solid fermentation substrate. Disperse the inoculation solution in an appropriate amount of sterile clean water, and then spray it into the solid fermentation substrate while spraying and stirring. Adjust the total moisture content of the fermentation substrate to 58% and stir thoroughly.

[0079] Aerobic fermentation involves spreading the inoculated material evenly in a fermentation device, controlling the fermentation temperature at 33°C, intermittently turning the pile to maintain an oxygen supply environment, and carrying out aerobic fermentation for 60 hours. During the fermentation process, microbial metabolism produces lactic acid, citric acid, amino acids, and small molecule peptides, which undergo complexation and chelation reactions with inorganic calcium, converting it into water-soluble organic calcium. The pH value of the material at the fermentation endpoint was measured to be 4.6.

[0080] After post-processing, the material is transferred to a drying device after fermentation and dried with low-temperature hot air at 48℃ until the moisture content of the material is 8%. The material is then crushed, sieved, and packaged to obtain a high-conversion-rate organic calcium product.

[0081] Comparative Examples 1-5:

[0082] Comparative Example 1:

[0083] Compared with Example 1, the difference is that Aspergillus niger and Bacillus subtilis are not added to the compound transformation strain composition. Instead, it is composed of Lactobacillus plantarum, Lactobacillus fermentum and Saccharomyces cerevisiae in the original proportions. All other aspects are the same.

[0084] Comparative Example 2:

[0085] Compared with Example 1, the difference is that the compound transformation inoculum is prepared using only a single Lactobacillus plantarum for activation, the inoculum amount is the same, and everything else is the same.

[0086] Comparative Example 3:

[0087] Compared with Example 1, the difference is that the moisture adjustment, inoculation and fermentation steps are omitted. Instead, pure lactic acid and citric acid aqueous solution with the same chemical equivalent as the fermentation product of Example 1 are directly added to the solid substrate after raw material pretreatment. Chemical acid-base mixing and neutralization are carried out directly. The drying conditions remain unchanged, and everything else is the same.

[0088] Comparative Example 4:

[0089] Compared with Example 1, the difference is that the aerobic fermentation step is changed to sealing the material in a fermentation bag for absolute anaerobic fermentation, while the rest are the same.

[0090] Comparative Example 5:

[0091] Compared with Example 1, the difference is that the post-processing step is changed to use high-temperature hot air at 85°C to quickly dry to the same moisture content, while the rest are the same.

[0092] Test Examples 1-4:

[0093] Test Example 1:

[0094] The fermentation processes of Example 1 and Comparative Example 1 were selected as test subjects to examine the differences in metabolite generation and microenvironment changes between a multi-strain synergistic system and a system lacking specific functional strains. After the fermentation process started, solid fermentation substrate samples were collected from multiple points at different depths of the fermentation device at five time points: 0 hours, 12 hours, 24 hours, 48 ​​hours, and 60 hours. Each sample was 50 grams and was quickly placed in an ice bath to terminate microbial metabolic activity.

[0095] The collected solid sample was added to ultrapure water at a solid-liquid weight ratio of 1:10 and extracted by shaking at 200 rpm for 30 minutes at room temperature. Then, it was centrifuged at 8000 rpm for 15 minutes at 4 degrees Celsius, and the supernatant was collected for later use. A portion of the unfiltered supernatant was taken, and the real-time pH value of the system was directly measured and recorded using a precision pH meter calibrated with standard buffer solution.

[0096] The remaining supernatant was filtered through a 0.22-micron aqueous microporous membrane. The filtrate was injected into a high-performance liquid chromatograph equipped with a UV detector. A C18 column was used, and isocratic elution was performed with a mixture of potassium dihydrogen phosphate aqueous solution and methanol as the mobile phase. The absolute concentrations of lactic acid and citric acid in the fermentation system were quantitatively determined.

[0097] Take another portion of the filtered supernatant and determine the content of free amino acids and small peptides in the system using the ninhydrin colorimetric method. Add hydrated ninhydrin reagent and a buffer solution of a specific pH to an appropriate amount of filtrate, heat in a boiling water bath for 15 minutes for color development, and after cooling, measure the absorbance at a wavelength of 570 nm using a UV-Vis spectrophotometer. Calculate the equivalent weight concentration of free amino acids by referring to the standard curve.

[0098] Table 1. Test data of core metabolites and pH value during fermentation in Example 1 and Comparative Example 1

[0099]

[0100] Figure 1 It contains four sub-graphs, of which (a) is the dynamic change graph of pH value of the system, (b) is the dynamic change graph of lactic acid production, (c) is the dynamic change graph of citric acid production, and (d) is the dynamic change graph of free amino acid production. Figure 1 The test data for Example 1 are marked with solid black lines and solid circles, while the test data for Comparative Example 1 are marked with dashed black lines and hollow squares.

[0101] According to the data in Table 1, the fermentation system of Example 1 maintained a stable substrate degradation and product accumulation process over a 60-hour period. In the early stages of fermentation, the pH values ​​of both systems showed a decreasing trend, but as time progressed, the pH value of Comparative Example 1 stagnated at around 5.3. This stagnation is directly related to the fact that the lactic acid concentration in Comparative Example 1 tended to plateau after 48 hours, indicating that relying solely on the single glycolysis pathway of lactic acid bacteria is easily limited by local acid stress and carbon source conversion bottlenecks. Example 1 maintained a longer-lasting acid-producing capacity, with the pH value steadily penetrating the critical point of 5.0 and eventually stabilizing at 4.48, forming an ideal acidic microenvironment for the large-scale dissociation of inorganic calcium sources. A more crucial difference lies in the changes in the concentrations of citric acid and free amino acids. Since Aspergillus niger and Bacillus subtilis were removed in Comparative Example 1, there was no substantial accumulation of citric acid in the system, and the amino acid concentration remained at the substrate level. The large-molecule organic nitrogen source has a dense structure, making it difficult for conventional lactic acid bacteria to effectively degrade it. The large-scale release of free amino acids in Example 1 benefited from the extracellular proteases secreted by Bacillus subtilis. Based on this, *Aspergillus niger* consumes free carbon sources through the tricarboxylic acid cycle overflow metabolism, releasing citric acid at a rate as high as 86.4 mg / g. Among these metabolites, the α-amino and carboxyl groups of free amino acids, combined with the polycarboxyl structure of citric acid, coordinate with the dissociated free calcium ions within a suitable pH range. Data from Comparative Example 1 conversely confirms that, in the absence of polydentate ligands, even in the presence of lactic acid, a stable chelate structure encapsulating calcium ions cannot be constructed, limiting the biochemical reaction to simple acid-base neutralization and hindering the efficient conversion of organic calcium.

[0102] Test Example 2:

[0103] The fermentation systems of Example 1 and Comparative Example 1 were selected as experimental subjects. Multiple samples were taken at 0, 12, 24, 48 and 60 hours of fermentation. The collected solid matrix was placed in a vacuum drying oven at 60 degrees Celsius and dried to constant weight. Then, it was ground with an agate mortar and passed through a 60-mesh sieve to obtain the dry basis test powder.

[0104] Weigh a certain amount of dry powder and place it in an Erlenmeyer flask. Add ultrapure water at a solid-liquid ratio of 1:50. Extract the powder by shaking in a constant temperature water bath at 37°C and 150 rpm for 2 hours. Collect the supernatant by centrifugation. Adjust the pH of the system to approximately 10 by adding ammonia-ammonium chloride buffer solution to the supernatant. Using Eriochrome Black T as an indicator, perform complexometric titration with a known accurate concentration of EDTA standard solution. Record the volume consumed to calculate the absolute weight content of water-soluble calcium.

[0105] The precipitate after centrifugation was washed twice with ultrapure water and transferred to a beaker. An excess of 2 mol / L hydrochloric acid solution was added and the mixture was gently heated to completely dissolve the residual insoluble inorganic calcium in the precipitate. After filtration to remove insoluble residue, the calcium ion concentration of the filtrate was determined by EDTA complexometric titration, and the residual insoluble inorganic calcium content in the system was calculated accordingly.

[0106] Based on the total calcium content (i.e., the sum of water-soluble calcium and insoluble inorganic calcium), the weight percentage of water-soluble calcium in the total calcium is calculated, and this value is used as the evaluation index of inorganic calcium conversion rate at the corresponding time point.

[0107] Table 2. Dynamic test data of inorganic calcium conversion during fermentation in Example 1 and Comparative Example 1

[0108]

[0109] Figure 2 The graph contains two sub-graphs. (a) is a graph showing the dynamic changes in the content of water-soluble and insoluble calcium. In this graph, the black solid circle represents the water-soluble calcium data of Example 1, the black solid triangle represents the insoluble calcium data of Example 1, the black dashed square represents the water-soluble calcium data of Comparative Example 1, and the black dashed rhombus represents the insoluble calcium data of Comparative Example 1. (b) is a graph showing the dynamic changes in the inorganic calcium conversion rate. In this graph, the black solid circle represents the inorganic calcium conversion rate data of Example 1, and the black dashed square represents the inorganic calcium conversion rate data of Comparative Example 1.

[0110] According to the data in Table 2, Example 1 completed a large-scale conversion of insoluble calcium to water-soluble calcium within a 60-hour fermentation cycle. At the initial stage (0 hours), the proportion of water-soluble calcium in both samples was extremely low, with the vast majority of calcium elements locked within the inorganic lattice structure. After 24 hours of fermentation, the water-soluble calcium content in Example 1 climbed to 53.48 mg / g, while that in Comparative Example 1 only reached 24.67 mg / g. During water extraction, the dry powder of Example 1 dissolved faster, and the amount of undissolved precipitate was significantly reduced. Considering the changes in the microstructure, the efficient conversion of inorganic calcium is not merely a simple acid-base neutralization reaction. In Comparative Example 1, the conversion rate stagnated at around 33% after 48 hours, and the residual amount of insoluble inorganic calcium remained as high as 65.41 mg / g, indicating that relying solely on single acids such as lactic acid can only dissolve the inorganic calcium on the surface of the matrix. With the buffering effect of increased local free calcium ion concentration and carbonate release, the single-strain system rapidly reached chemical dissolution equilibrium.

[0111] The preceding test examples confirmed the accumulation of high concentrations of citric acid and free amino acids in the fermentation system. When free calcium ions detach from the crystal lattice, the carboxyl and amino groups of these molecules capture them through electrostatic attraction and coordination bonds, self-assembling into a three-dimensional composite structure with internal charge neutralization and external hydrophilicity. This in-situ chelation mechanism continuously consumes free calcium ions in the aqueous phase, forcing a rightward shift in the solid-liquid dissolution equilibrium and promoting the continuous dissociation of the inorganic calcium lattice. The final conversion rate of 91.42% in Example 1 confirms the binding ability of multiple organic ligands for metal ions, explaining the mechanism by which the multi-strain composite system overcomes the limitations of a single chemical reaction and ensures the continuous generation of water-soluble organic calcium. The high conversion rate of 91.42% in Example 1 directly confirms the strong binding ability of multiple organic ligands for metal ions, explaining, both macroscopically and microscopically, how the multi-strain composite system overcomes the limitations of a single chemical reaction and ensures the large-scale continuous generation of highly active bio-organic calcium.

[0112] Test Example 3:

[0113] The final dried and pulverized products prepared in Examples 1 to 5 and Comparative Examples 1 to 5 were selected as experimental subjects for comprehensive evaluation to verify the final effects of various process conditions on the physicochemical weight and microecological activity of the products. 50 grams of samples were randomly selected from each batch, placed in sterile self-sealing bags, and stored under number. Parallel determinations of all indicators were completed within 24 hours of sampling.

[0114] Weigh 10 grams of each group of dried finished product powder, add 90 ml of boiled, cooled, and degassed ultrapure water, and stir vigorously at 500 rpm for 20 minutes on a magnetic stirrer to fully dissolve the soluble substances. After standing and separating the layers, insert the pH meter composite electrode calibrated with two-point standard buffer solution into the supernatant. After the reading stabilizes, record the pH value of the water extract, which will be used as the equivalent pH control index for the corresponding fermentation endpoint.

[0115] The distribution of calcium was quantitatively determined using either isotope dilution or classical EDTA complexometric titration. Two grams of the final product were accurately weighed and placed in a constant-temperature water bath shaker. Water-soluble free calcium and coordinated organic calcium were extracted with pure water. The total water-soluble calcium content in the supernatant was separated and determined. The residue at the bottom was treated with acid hydrolysis to break down the remaining unconverted inorganic lattice, and the content of sparingly soluble inorganic calcium was determined. Based on the total sample weight, the inorganic calcium conversion rate and the weight percentage of water-soluble calcium in the total calcium were calculated.

[0116] Weigh 1 gram of the finished product sample obtained under aseptic conditions and add it to 9 ml of sterile physiological saline containing 0.1% peptone. After thorough shaking and dispersing, perform a tenfold serial dilution. Select three appropriate serial dilutions, and spread 0.1 ml of each onto pre-prepared MRS agar and potato dextrose agar mixed medium plates. Incubate in an inverted position at 37°C for 48 to 72 hours. Record the effective colony count and convert it to the total viable count per gram of finished product.

[0117] Table 3. Test data of core physicochemical and microecological indicators for the examples and comparative examples

[0118]

[0119] Figure 3 It contains three vertically arranged sub-graphs, where (a) is the equivalent pH level of each batch of finished product, (b) is the comparison of inorganic calcium conversion rate and water-soluble calcium content, and (c) is the comparison of live bacteria in the finished product.

[0120] According to the data in Table 3, the example group demonstrated extremely high process stability and technical superiority under the established key control index system. When compiling the test results of Examples 1 to 5 under different ratios, we found that regardless of changes in the substrate formulation or adjustments to the process boundaries, the fermentation endpoint pH was consistently anchored within the slightly acidic range of 4.0 to 5.0. This directly ensured that the inorganic calcium conversion rate of all examples jumped to over 85%, and the proportion of water-soluble calcium consistently exceeded 90%. This astonishing uniformity of conversion demonstrates that the multi-species synergistic network has a strong adaptive buffering capacity for the degradation of different substrates and ligand generation. Turning our attention to the comparative data, Comparative Example 1, which separated Bacillus subtilis and Aspergillus niger, and Comparative Example 2, which degenerated into a single species, showed a precipitous drop in conversion rate. This revealed that the lack of high-dimensional coordination involving multidentate ligands (such as free amino acids and citric acid) meant that the slight acidity alone could not shake the lattice fortress of inorganic salts.

[0121] In Comparative Example 3, the direct addition of acid-base reagents did lower the pH to 4.52, but the conversion rate remained at only 65.48%. This forced reaction within a physically mixed space, lacking the dynamic ligand supply continuously pumped out by the microbial system over time, resulted in free calcium ions easily re-precipitating after local concentration saturation, producing a large amount of insoluble complex salt residue. Most critically, the viable bacterial count approached zero, completely negating the added value of intestinal microecological regulation. The destructive power of the anaerobic environment was clearly demonstrated in Comparative Example 4; blocking the aerobic pathway directly led to the extinction of the aerobic functional bacteria population, causing the fermentation microenvironment to collapse rapidly. Not only did the acidity fail to decrease, but the conversion rate was also the lowest at 21.75%. When discussing post-treatment parameters, the data from Comparative Example 5 provides a highly valuable counter-example. Although the high-temperature drying did not destroy the organic chelated calcium structure formed during the initial fermentation (its conversion rate and water-soluble calcium remained above 90%), the intense heat exceeding 85°C instantly killed heat-sensitive probiotics such as *Lactobacillus plantarum* accumulated in the product, causing the viable bacterial count to drop to 0.006 × 10⁻⁶. 9 CFU / g.

[0122] Test Example 4:

[0123] Sixty healthy weaned piglets of similar age and uniform weight were selected as experimental subjects and randomly divided into three treatment groups: a blank control group fed with a basal diet, a chemical group fed with a basal diet supplemented with the chemical mixture of Example 3, and a fermented group fed with a basal diet supplemented with the bio-organic calcium product of Example 1. The total calcium level in the diets of each group was kept consistent through formula adjustments and the piglets were fed continuously for 28 days.

[0124] During the feeding period, the feed intake and defecation status of each group of piglets were recorded at regular intervals every day, and the number of diarrhea occurrences was counted in detail to calculate the average diarrhea rate during the entire experimental period.

[0125] During the last three days of the experiment, piglet fecal samples were collected using the endogenous indicator method. After drying and pulverizing the feces, the absolute contents of the indicator and calcium in the feed and feces were determined, and the apparent digestibility and absorption rate of calcium were calculated.

[0126] After the feeding cycle ended, six piglets were randomly selected from each group for painless dissection. The attached muscle of the right tibia was removed, and the tibia was defatted, dried, and ashed at high temperature. The ash content of the tibia was calculated by weighing, and the calcium deposition content in the tibia was determined by atomic absorption spectrometry. At the same time, chyme from the middle section of the cecum was collected, and the effective logarithmic proliferation of lactobacilli and coliforms in the chyme was determined by gradient dilution spread method.

[0127] Table 4. Data on in vivo absorption and dual-effect microecological health care in animals of the examples and comparative examples

[0128]

[0129] Figure 4 It contains three subplots: (a) is a graph of apparent digestion and tibial deposition of calcium, where solid circles represent apparent digestibility and dashed triangles represent the amount of calcium deposited in the tibia; (b) is a graph of average diarrhea rate during the test period, with solid square broken lines showing the data distribution; and (c) is a graph of cecal core microecological flora concentration.

[0130] According to the data in Table 4, the utilization efficiency of different forms of calcium sources varies in the actual physiological environment within animals. In conventional farming scenarios, weaned piglets have insufficient gastric acid secretion, leading to difficulty in dissociating inorganic salts such as calcium carbonate in the blank control group. The apparent digestibility of 42.34% reflects the objective situation that inorganic salts are difficult to absorb. Comparative Example 3 provides some soluble calcium by adding acid-base reagents, increasing the digestibility to 58.71%. However, after this simple calcium salt enters the intestine, as the pH gradually approaches neutral to alkaline, free calcium easily re-complexes and precipitates with phytic acid or free fatty acids. The high apparent digestibility of 76.45% in Example 1 group originates from the complex ligand network produced by multi-strain fermentation. The multidentate chelate structure of calcium ions, co-encapsulated by free amino acids, lactic acid, and citric acid, observed in previous studies, maintains the electroneutrality and high solubility of the molecule under gastric acid impact and changes in the intestinal fluid environment, enabling active absorption of calcium through amino acid transport channels. The large amount of calcium entering the bloodstream increases the metabolic level of bone tissue, and the tibial ash content and calcium deposition in Example 1 are higher than those in the previous two groups.

[0131] The diarrhea rate in the control group and Comparative Example 3 remained at a high level of over 11%, and the abundance of *E. coli* in the cecum was higher than that of *Lactobacillus*, indicating an imbalance in the intestinal microenvironment that reduced feed conversion rate. Dissection of piglets in Example 1 revealed a full intestinal wall and good digestible characteristics. Data showed that the *E. coli* titer decreased to 6.37 lg CFU / g, *Lactobacillus* established a dominant flora (8.91 lg CFU / g), and the diarrhea rate decreased to 3.25%. The dormant *Lactobacillus plantarum* and *Bacillus subtilis* in the Example 1 product rapidly revived after entering the intestines with the diet, working synergistically with the lactic acid and oligopeptide metabolites present in the product to rapidly lower the local pH in the cecum. This biological presence and acidic environment constituted a natural barrier against pathogenic *E. coli*. The Example 1 product contained *Lactobacillus plantarum* and *Bacillus subtilis*, which proliferated and remained dormant during the solid-state fermentation stage. These active probiotics rapidly revived after entering the intestines with the diet, working synergistically with the lactic acid and oligopeptide metabolites present in the product to rapidly lower the local pH in the cecum. This biological presence and acidic environment constitute a natural physicochemical barrier against pathogenic Escherichia coli.

Claims

1. A fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation, characterized in that... Includes the following steps: Weigh out the raw materials containing inorganic calcium source, carbon source feed, nitrogen source feed and auxiliary materials, mix the raw materials evenly and crush and sieve them to obtain solid fermentation substrate; Then, take the pre-prepared compound transformation inoculum solution, the amount of which is calculated as 0.8%-1.5% of the total dry weight of the solid fermentation substrate, and disperse the compound transformation inoculum solution in sterile clean water. Then, spray the dispersed inoculum solution directly into the solid fermentation substrate. While spraying and stirring, adjust the overall moisture content of the solid fermentation substrate and mix it thoroughly to obtain the inoculated material. Next, the inoculated material is spread out in the fermentation device for aerobic fermentation, producing organic small molecule metabolites, which undergo complexation and chelation reactions with the inorganic calcium in the inorganic calcium source, converting the inorganic calcium into water-soluble organic calcium, and obtaining the fermented material. After fermentation, the fermented material is transferred to a drying device and dried and dehydrated under low-temperature hot air conditions. Finally, it is crushed, sieved and packaged to obtain organic calcium products.

2. The fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation according to claim 1, characterized in that, The raw materials, by weight, include: Inorganic calcium source: 20-30 parts; Carbon source feed: 40-55 parts; Nitrogen source feed: 10-18 parts; Additional ingredients: 3-8 parts.

3. The fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation according to claim 2, characterized in that, The specific types of raw materials are: The inorganic calcium source is one or more of the following: stone powder, shell powder, dicalcium phosphate, and bone meal; The carbon source feed is one or more of corn flour, wheat bran, and rice bran; The nitrogen source feed is one or more of soybean meal, corn steep liquor powder, and yeast powder; The excipients are brown sugar and an inorganic salt buffer, which is a mixture of potassium dihydrogen phosphate and disodium hydrogen phosphate in a weight ratio of 1:

1.

4. The fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation according to claim 1, characterized in that, The inoculum solution for the composite transformation strain is prepared by activating the dry powder of the composite transformation strain composition with a brown sugar aqueous solution. The dry powder of the composite transformation strain composition is composed of a mixture of live bacterial powders of each single strain in parts by weight, including: Lactobacillus plantarum: 25-35 portions; Lactobacillus fermentum: 15-25 parts; Aspergillus niger: 10-15 parts; Bacillus subtilis: 15-20 parts; Brewing yeast: 8-12 parts.

5. The fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation according to claim 4, characterized in that, The activation preparation method of the composite transformation strain inoculum includes: The single-strain live bacterial powders are mixed to prepare a formula with a total live bacterial content of not less than 5.0 × 10⁻⁶. 9 The compound transforming bacterial composition dry powder with CFU / g; The dry powder of the composite transforming strain composition was added to a 5% brown sugar aqueous solution at a weight ratio of 1:10, and the mixture was slowly stirred and activated at room temperature for 1-2 hours to obtain the inoculum solution of the composite transforming strain.

6. The fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation according to claim 1, characterized in that, The sieve mesh size for the crushing and sieving process is 20-40 mesh; In addition, the overall moisture content of the solid fermentation substrate is adjusted to 55%-60%.

7. The fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation according to claim 1, characterized in that, The conditions for the aerobic fermentation are as follows: The fermentation temperature is controlled at 30-37℃, and aerobic fermentation is carried out for 48-72 hours. An intermittent oxygen supply environment is maintained by intermittent turning or intermittent ventilation.

8. The fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation according to claim 7, characterized in that, When the aerobic fermentation is completed, the pH value of the fermented material is 4.0-5.

0.

9. The fermentation process for preparing organic chelated calcium feed additives from inorganic calcium via microbial transformation according to claim 1, characterized in that, The organic small molecule metabolites include one or more of lactic acid, citric acid, amino acids, and small molecule peptides.

10. The fermentation process according to claim 1, characterized in that, The conditions for drying and dehydration under low-temperature hot air conditions are as follows: The material is dried with hot air at 40-55℃ until the moisture content of the fermented material is 6%-10%.

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