A method for preparing iron-zinc-selenium-enriched yeast
By simultaneously enriching iron, zinc, and selenium in yeast, the problems of cumbersome yeast preparation and inconvenient use in existing technologies have been solved, achieving efficient and stable micronutrient conversion and nutritional value enhancement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GANSU ACAD OF SCI INST OF BIOLOGY
- Filing Date
- 2020-10-12
- Publication Date
- 2026-05-26
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of microbial technology, and in particular relates to a method for preparing iron-, zinc-, and selenium-enriched yeast. Background Technology
[0002] Trace elements play a vital role in maintaining normal physiological metabolism in humans and animals; deficiencies can lead to disease. Inorganic trace elements are highly toxic and poorly absorbed by the body, while organic trace elements are rapidly absorbed. Microorganisms can convert inorganic trace elements into easily absorbed organic forms, with yeast, known for its strong ability to accumulate trace elements, being a commonly used microorganism. Yeast cells are rich in proteins, B vitamins, fats, sugars, enzymes, and other nutrients. They are easy to cultivate, produce numerous metabolic products, regulate the microecological balance within organisms, enhance immunity, and are non-toxic with a short growth cycle. Adding trace element-enriched yeast to feed not only improves its nutritional value but also helps increase the utilization rate of other nutrients in the feed, thus making yeast a promising candidate for application in the feed industry.
[0003] Iron, zinc, and selenium are all essential trace elements for humans and animals. Iron is a crucial component of heme, myoglobin, and cytochromes in organisms. Iron deficiency can cause anemia, weakened immune function, and trigger various diseases. Currently, most iron supplements suffer from low bioavailability and adverse effects on food flavor. Iron-enriched yeast, however, boasts advantages such as good stability, safety, and high absorption and utilization rates. Furthermore, its high protein, essential amino acid, and vitamin content significantly enhances its nutritional value. Zinc is an essential component of many enzymes and plays vital physiological functions. Zinc deficiency can lead to stunted growth. Zinc-enriched yeast, as a zinc supplement, can improve bioavailability, regulate the body's microecology, and enhance immunity. Selenium plays a vital role in normal physiological metabolism and disease resistance. It possesses antioxidant properties, inhibiting energy metabolism in cancer cells and enhancing immunity. Its absence can cause diseases such as Keshan disease, Kashin-Beck disease, and white muscle disease in livestock; it can also lead to cardiovascular diseases, hypertension syndrome, and gastrointestinal disorders. Selenium-enriched yeast has a high selenium enrichment capacity and has been proven to be safer, more stable, easier to absorb, and less polluting than inorganic selenium. It has multiple health benefits and has gradually gained recognition in recent years, with its application in animal husbandry becoming increasingly widespread.
[0004] Currently, there are yeasts enriched with single trace elements, such as iron-enriched yeast, zinc-enriched yeast, chromium-enriched yeast, selenium-enriched yeast, iodine-enriched yeast, and copper-enriched yeast. In application, different types of trace elements can be supplemented by adding multiple yeasts enriched with different trace elements. However, when formulated with food or feed, the dosage of each yeast needs to be calculated individually based on the amount of trace element enriched, which is inconvenient. Furthermore, the process of preparing yeast enriched with each trace element separately is quite cumbersome, increasing costs and limiting its application. Summary of the Invention
[0005] To address the shortcomings mentioned in the background section, this invention provides a method for preparing iron-zinc-selenium-enriched yeast, which efficiently converts organic iron, zinc, and selenium into organic forms and simultaneously enriches them within the same yeast cell.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A method for preparing iron-zinc-selenium-enriched yeast, the method comprising the following steps:
[0008] (1) Add sterilized inorganic iron solution and inorganic zinc solution to the sterilized YPD medium to increase the Fe concentration in the medium. 2+ Final concentration of 150-300 mg / L, Zn 2+ The final concentration is 100-300 mg / L, and it should be stored at 4℃ for later use.
[0009] (2) The yeast was activated. The yeast strain used was deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 20630, classified as *Saccharomyces cerevisiae*, deposited on September 11, 2020, at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The activated yeast was inoculated into the culture medium from step (1) at a 10% inoculum. The initial pH of the culture medium was adjusted to 6-8, the rotation speed was 150-200 r / min, the liquid volume was (50-100) mL / 250 mL, and the culture was carried out at 28-32℃. After 6 hours of culture, sterilized inorganic selenium solution was added to the culture medium to increase the concentration of Se in the culture medium. 2+ The final concentration is 15-30 mg / L. Continue culturing for 36-60 h, then centrifuge to collect the bacterial cell fraction.
[0010] (3) The collected bacterial cells are washed with distilled water 3-5 times and dried at a constant temperature of 60℃ to obtain iron, zinc and selenium-enriched yeast.
[0011] Preferably, the inorganic iron solution is a ferrous sulfate solution, the inorganic zinc solution is a zinc sulfate solution, and the inorganic selenium solution is a sodium selenite solution.
[0012] Preferably, the Fe 2+ and Zn 2+ The final concentration of all was 200 mg / L, and the Se 2+ The final concentration is 15 mg / L.
[0013] Preferably, the pH value is 6.5, the fermentation temperature is 32℃, the liquid volume is 50mL / 250mL, and after adding sterilized inorganic selenium solution, the culture is continued for 36 hours, and then the bacterial cells are collected by centrifugation.
[0014] The present invention further provides an iron-zinc-selenium-enriched yeast strain prepared by the above method.
[0015] This invention further provides the application of iron-, zinc-, and selenium-enriched yeast in food or feed.
[0016] Compared with the shortcomings and deficiencies of existing technologies, the present invention has the following beneficial effects:
[0017] This invention enriches three essential trace elements—iron, zinc, and selenium—within a single yeast strain, meaning that fermenting one yeast strain can simultaneously yield iron-enriched, zinc-enriched, and selenium-enriched yeast. The preparation process is easy to cultivate, has a short fermentation cycle, and is simple. The prepared iron-, zinc-, and selenium-enriched yeast is easy to process and store, exhibits good stability, high conversion rates of organic iron, zinc, and selenium, good compatibility with various food and feed components, and a pleasant flavor. It not only provides essential iron, zinc, and selenium for humans and animals but is also rich in protein, B vitamins, fats, sugars, enzymes, and other nutrients. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0019] The iron-zinc-selenium-enriched yeast strain provided in this invention is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 20630, classified as *Saccharomyces cerevisiae*, deposited on September 11, 2020, at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The prepared iron-zinc-selenium-enriched yeast strain can be added to food or animal feed.
[0020] Example
[0021] (1) Sterilized ferrous sulfate solution and zinc sulfate solution were added to the sterilized YPD medium, and multiple sets of experiments were conducted to adjust the Fe content in the medium.2+ and Zn 2+ Different final concentrations, store at 4℃ for later use.
[0022] (2) Inoculate the activated yeast at a rate of 10% into the above culture medium, and adjust the fermentation conditions, including the initial pH of the culture medium, the volume of liquid, the fermentation temperature, and the rotation speed of 150 r / min to 200 r / min. After fermenting for 6 hours, add sterilized sodium selenite solution to adjust the Se content in the culture medium. 2+ After reaching the final concentration, continue culturing for a certain period of time, and then centrifuge to collect the bacterial cells.
[0023] (3) The collected bacterial cells are washed with distilled water 3-5 times and dried at a constant temperature of 60℃ to obtain iron, zinc and selenium-enriched yeast.
[0024] Fe in the experiment 2+ Zn 2+ Se 2+ The final concentrations are set as follows:
[0025] Fe 2+ The final concentrations were 50 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, 300 mg / L, 400 mg / L, and 600 mg / L, respectively.
[0026] Zn 2+ The final concentrations are: 50 mg / L, 100 mg / L, 200 mg / L, 300 mg / L, 400 mg / L, 500 mg / L, and 600 mg / L.
[0027] Se 2+ The final concentrations are: 10 mg / L, 15 mg / L, 20 mg / L, 30 mg / L, and 40 mg / L.
[0028] Fermentation conditions: pH 5.5–8.5, fermentation temperature 26℃–32℃, rotation speed 150 r / min–200 r / min, liquid volume 25 mL–125 mL / 250 mL, fermentation time 12 h–72 h.
[0029] The iron and zinc contents of yeast cells prepared under different conditions were determined by flame atomic absorption spectrophotometry; the selenium contents of yeast cells were determined by the 3,3'-diaminobenzidine (3,3'-DAB) colorimetric method.
[0030] First, optimize Fe. 2+ Zn 2+ Se 2+The final concentration and fermentation conditions were set as follows: pH 7.0, fermentation temperature 30℃, rotation speed 200 r / min, liquid volume 60 mL / 250 mL, and fermentation time 36 h. The results of trace element content determination in yeast cells prepared under these conditions are shown in Table 1.
[0031] Table 1 Different Fe 2+ Zn 2+ Se 2+ Trace element content of yeast cells at final concentration
[0032]
[0033]
[0034] Table 1 shows that the trace element content of yeast cells prepared under conditions 3-6 in experimental groups was significantly higher than that in other experimental groups. Therefore, Fe 2+ The preferred final concentration is 150-300 mg / L, Zn 2+ The preferred final concentration is 100-300 mg / L, Se 2+ The preferred final concentration is 15-30 mg / L, with Fe as the main component. 2+ Zn 2+ Se 2+ The highest conversion rates of trace elements were observed when the final concentrations were 200 mg / L, 200 mg / L, and 15 mg / L.
[0035] Secondly, optimize fermentation conditions, Fe 2+ Zn 2+ Se 2+ The final concentrations were 200 mg / L, 200 mg / L, and 15 mg / L, respectively. The fermentation conditions were set as follows: pH 5.5-8.5, fermentation temperature 26-32℃, liquid volume 25-125 mL / 250 mL, and fermentation time 12-72 h. The results of the trace element content determination of yeast cells prepared under these conditions are shown in Table 2.
[0036] Table 2. Trace element content of yeast cells prepared under different fermentation conditions
[0037]
[0038] Table 2 shows that the trace element content of yeast cells prepared under conditions 4-7, 9, and 11-12 was significantly higher than that of other experimental groups. Therefore, the optimal fermentation conditions are as follows: pH 6-8, fermentation temperature 28-32℃, liquid volume 50-100mL / 250mL, and fermentation time 36-60h. Among these, the optimal fermentation conditions are: pH 6.5, fermentation temperature 32℃, liquid volume 50mL / 250mL, and fermentation time 36h. Under these conditions, the iron-zinc-selenium-enriched yeast obtained had a cell biomass of 0.35g, a cell selenium content of 20mg / kg, a cell iron content of 1500mg / kg, and a cell zinc content of 30mg / kg, with high conversion rates of organic iron, zinc, and selenium.
[0039] Comparative Example 1
[0040] (1) Add sterilized ferrous sulfate solution, zinc sulfate solution, and sodium selenite solution to the sterilized YPD medium to make the Fe concentration in the medium... 2+ Zn 2+ Se 2+ The final concentrations were 200 mg / L, 200 mg / L, and 15 mg / L, respectively, and stored at 4°C for later use.
[0041] (2) Inoculate the activated yeast at a rate of 10% into the above culture medium, and adjust the fermentation conditions as follows: pH 6.5, rotation speed 150r / min~200r / min, liquid volume 50mL / 250mL, culture at 32℃ for 6h, and then centrifuge to collect the cell portion.
[0042] (3) The collected bacterial cells are washed with distilled water 3-5 times and dried at a constant temperature of 60℃ to obtain iron, zinc and selenium-enriched yeast.
[0043] Comparative Example 2
[0044] (1) Add sterilized ferrous sulfate solution and sodium selenite solution to the sterilized YPD medium to increase the Fe concentration in the medium. 2+ Se 2+ The final concentrations were 200 mg / L and 15 mg / L, respectively, and stored at 4℃ for later use.
[0045] (2) Inoculate the activated yeast at a rate of 10% into the above culture medium, and adjust the fermentation conditions as follows: pH 6.5, rotation speed 150 r / min to 200 r / min, liquid volume 50 mL / 250 mL, and culture at 32℃. After 6 hours of culture, add sterilized zinc sulfate solution to adjust the Zn concentration in the culture medium. 2+ The final concentration was 200 mg / L, and the cells were cultured for another 36 hours. The cells were then collected by centrifugation.
[0046] (3) The collected bacterial cells are washed with distilled water 3-5 times and dried at a constant temperature of 60℃ to obtain iron, zinc and selenium-enriched yeast.
[0047] Comparative Example 3
[0048] (1) Add sterilized zinc sulfate solution and sodium selenite solution to the sterilized YPD medium to make the Zn concentration in the medium... 2+ Se 2+ The final concentrations were 200 mg / L and 15 mg / L, respectively, and stored at 4℃ for later use.
[0049] (2) Inoculate the activated yeast at a rate of 10% into the above culture medium, and adjust the fermentation conditions as follows: pH 6.5, rotation speed 150 r / min to 200 r / min, liquid volume 50 mL / 250 mL, and culture at 32℃. After 6 hours of culture, add sterilized ferrous sulfate solution to adjust the Fe content in the culture medium. 2+ The final concentration was 200 mg / L, and the culture was continued for 36 hours. The bacterial cells were then collected by centrifugation.
[0050] (3) The collected bacterial cells are washed with distilled water 3-5 times and dried at a constant temperature of 60℃ to obtain iron, zinc and selenium-enriched yeast.
[0051] The results of the determination of trace element content in yeast cells prepared in Comparative Examples 1-3 are shown in Table 3.
[0052] Table 3. Trace element content of yeast cells prepared in Comparative Examples 1-3
[0053]
[0054] As shown in Table 3, the trace element content of yeast cells prepared in Comparative Examples 1-3 significantly affects the trace element content. The order in which inorganic iron, zinc, and selenium solutions are added during preparation has a crucial impact on the trace element content. Compared to Table 1 of the Examples, whether ferrous sulfate, zinc sulfate, and sodium selenite solutions are added first for culturing before yeast inoculation, or ferrous sulfate and sodium selenite solutions are added first, or zinc sulfate and sodium selenite solutions are added first for culturing before yeast inoculation, the resulting yeast cells with significantly lower trace element content are compared to those prepared under experimental groups 3-6 in Table 1. Therefore, in the preparation of yeast cells enriched for trace elements, ferrous sulfate and zinc sulfate solutions should be added first for culturing, followed by yeast inoculation for 6 hours, and then sodium selenite solution should be added for further culturing. This method yields yeast cells with higher trace element content.
[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing iron-, zinc-, and selenium-enriched yeast, characterized in that, The method includes the following steps: (1) Add sterilized inorganic iron solution and inorganic zinc solution to the sterilized YPD medium to increase the Fe concentration in the medium. 2+ Final concentration of 180-300 mg / L, Zn 2+ The final concentration is 180-300 mg / L, and it should be stored at 4℃ for later use. (2) The yeast was activated. The yeast strain used was deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 20630, classified as *Saccharomyces cerevisiae*, deposited on September 11, 2020, at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The activated yeast was inoculated into the culture medium from step (1) at a 10% inoculation rate. The initial pH of the culture medium was adjusted to 6-8, the rotation speed was 150-200 r / min, the liquid volume was (50-100) mL / 250 mL, and the culture was carried out at 28-32℃. After 6 hours of culture, sterilized inorganic selenium solution was added to the culture medium to increase the concentration of Se in the culture medium. 2+ The final concentration is 15-30 mg / L. Continue culturing for 36-60 h, then centrifuge to collect the bacterial cell fraction. (3) The collected bacterial cells are washed with distilled water 3-5 times and dried at a constant temperature of 60℃ to obtain iron, zinc and selenium-enriched yeast.
2. The method for preparing iron-zinc-selenium-enriched yeast as described in claim 1, characterized in that, The inorganic iron solution is ferrous sulfate solution, the inorganic zinc solution is zinc sulfate solution, and the inorganic selenium solution is sodium selenite solution.
3. The method for preparing iron-zinc-selenium-enriched yeast as described in claim 1, characterized in that, The Fe 2+ and Zn 2+ The final concentration of all was 200 mg / L, and the Se 2+ The final concentration is 15 mg / L.
4. The method for preparing iron-zinc-selenium-enriched yeast as described in claim 1, characterized in that, The pH value was 6.5, the fermentation temperature was 32℃, the liquid volume was 50mL / 250mL, and after adding sterilized inorganic selenium solution, the culture was continued for 36 hours before centrifugation to collect the bacterial cells.
5. An iron-, zinc-, and selenium-enriched yeast strain prepared by the preparation method according to any one of claims 1-4.
6. The application of an iron-zinc-selenium-enriched yeast prepared by any one of claims 1-4 in food or feed.