Method for rapidly cultivating upright branches of selenium-rich long-stem grape caulerpa lentillifera

Abstract

The invention relates to the technical field of selenium-rich culture of seaweed, in particular to a method for quickly culturing upright branches of selenium-rich long-stem caulerpa lentillifera. The method provided by the invention comprises the step of culturing the upright branches of the caulerpa lentillifera in a water body with the selenium element content of 0.15-0.25 mg / L for 8-24 hours to obtain the upright branches of the selenium-rich caulerpa lentillifera. The invention finds that long-time selenium-rich culture is not beneficial to the growth of the caulerpa lentillifera, aiming at the characteristic that the upright branches of the caulerpa lentillifera can still survive and grow after being harvested, the harvested upright branches are subjected to selenium-rich culture in a water body with a specific selenium element, and the selenium-rich upright branches of the caulerpa lentillifera (the selenium content is greater than or equal to 0.5 mg / kg) of the caulerpa lentillifera can be obtained within a short time (8-24 hours). Compared with a traditional selenium-rich agricultural product culture mode, the method is easy and convenient to operate, mature commodity upright branches serve as selenium-rich objects, cost is saved, efficiency can be improved, and the method is suitable for industrialized operation.

Description

Technical Field

[0001] The present invention relates to the technical field of selenium-enriched cultivation of seaweeds, and particularly to a method for rapidly cultivating upright branches of selenium-enriched Caulerpa lentillifera ( Caulerpa lentillifera ). Background Art

[0002] Caulerpa lentillifera is mainly distributed in the intertidal zones of tropical and subtropical waters in the western Pacific and Indian Oceans, on sandy beaches or reefs with slow water flow. It is also known as "sea grape" because of its external shape similar to grapes. Caulerpa lentillifera has a delicious taste, low calories, and is rich in essential minerals for the human body such as calcium, potassium, magnesium, and iron. It has very rich nutritional content and contains a large amount of DHA that can reduce cholesterol in human blood, and is an ideal health food.

[0003] Currently, in terms of the research and development of Caulerpa lentillifera, there are mainly two directions: 1) further in-depth research on cultivation conditions and nutritional requirements, including research at the gene level; 2) the aquaculture mode is gradually changing from extensive to intensive, and scientific research results are beginning to be applied to production practice and developing towards large-scale production. Therefore, improving the aquaculture environmental conditions and nutritional requirements and further enhancing the nutritional and economic value of the algal body are the main research directions of Caulerpa lentillifera at present. Therefore, exploring the selenium-enriching effect of Caulerpa lentillifera and cultivating selenium-enriched sea grape products can further enhance its value. However, there is currently little research on the selenium-enriched cultivation method of sea grapes, and the whole plant of sea grapes is cultivated, lacking a cultivation method that is suitable for factory production and is fast and simple. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a method for rapidly cultivating upright branches of selenium-enriched Caulerpa lentillifera. The method provided by the present invention is simple to operate, suitable for factory operation, and can quickly obtain selenium-enriched sea grape products with high selenium content.

[0005] In order to achieve the above object, the present invention provides the following technical solutions: The present invention provides a method for rapidly cultivating upright branches of selenium-enriched Caulerpa lentillifera, comprising: culturing upright branches of Caulerpa lentillifera in a water body containing 0.15 - 0.25 mg / L of selenium element for 8 - 24 hours to obtain upright branches of selenium-enriched Caulerpa lentillifera.

[0006] Preferably, the concentration of selenium element in the water body is 0.2 mg / L.

[0007] Preferably, the donor of the selenium element includes selenic acid.

[0008] Preferably, the culturing time is 8 - 12 hours.

[0009] Preferably, the water body includes seawater, nutrient salt mother liquor and a donor of selenium element; the volume ratio of the seawater to the nutrient salt mother liquor is 1000:0.2 - 0.3; the nutrient salt mother liquor includes components with the following concentrations: ammonium chloride 10.27 g / L, sodium nitrate 63.75 g / L, and sodium dihydrogen phosphate 4.8 g / L.

[0010] Preferably, the volume ratio of the seawater to the nutrient salt mother liquor is 1000:0.25.

[0011] Preferably, the salinity of the seawater is 30 - 32‰.

[0012] Preferably, the temperature for cultivation is 24 - 28 °C, and the light intensity is 25 - 35 μmol / m 2 ·s.

[0013] Preferably, the temperature for cultivation is 26 °C, and the light intensity is 30 μmol / m 2 ·s.

[0014] Preferably, the upright branches of Caulerpa lentillifera are the upright branches after the harvest of Caulerpa lentillifera.

[0015] Beneficial effects: The present invention provides a method for rapidly cultivating selenium - rich upright branches of Caulerpa lentillifera, including: culturing the upright branches of Caulerpa lentillifera in a water body with selenium element at 0.15 - 0.25 mg / L for 8 - 24 h to obtain selenium - rich upright branches of Caulerpa lentillifera. The present invention discovers that long - term selenium - rich cultivation is not conducive to the growth of Caulerpa lentillifera. In view of the characteristic that the upright branches of Caulerpa lentillifera can still survive and grow after harvest, the harvested upright branches are subjected to selenium - rich cultivation in a water body with a specific selenium element, and selenium - rich upright branches of Caulerpa lentillifera (selenium content ≥ 0.5 mg / kg) can be obtained within a short time (8 - 24 h). Compared with the traditional cultivation method of selenium - rich agricultural products, the method provided by the present invention is simple to operate, uses mature commercial upright branches as the selenium - rich object, which not only saves costs but also improves efficiency, and is suitable for industrial operation. Description of the drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments.

[0017] Figure 1 Shows the influence result of the addition of selenic acid on the daily growth rate of Caulerpa lentillifera; Figure 2 Shows the influence result of the addition of selenic acid on the thallus morphology of Caulerpa lentillifera; Figure 3 Shows the influence result of the addition of selenic acid on the selenium content of Caulerpa lentillifera; Figure 4Selenium content in the upright branches of Caulerpa lentillifera after selenium-enriched culture at different selenic acid concentrations. Detailed implementation mode

[0018] The present invention provides a method for rapidly cultivating selenium-enriched upright branches of Caulerpa lentillifera, comprising: culturing the upright branches of Caulerpa lentillifera in water with 0.15 - 0.25 mg / L of selenium element for 8 - 24 h to obtain selenium-enriched upright branches of Caulerpa lentillifera.

[0019] As an implementation mode, the concentration of selenium element in the water is 0.2 mg / L. As an implementation mode, the water body comprises seawater, nutrient salt mother liquor and a donor of selenium element; the volume ratio of the seawater to the nutrient salt mother liquor is 1000:0.2 - 0.3; the nutrient salt mother liquor comprises components with the following concentrations: ammonium chloride 10.27 g / L, sodium nitrate 63.75 g / L and sodium dihydrogen phosphate 4.8 g / L. As an implementation mode, the volume ratio of the seawater to the nutrient salt mother liquor is 1000:0.25. As an implementation mode, the salinity of the seawater is 30 - 32‰. As another implementation mode, the salinity of the seawater is 31‰. As an implementation mode, the donor of selenium element can be selenic acid. The nutrient salt mother liquor provided by the present invention uses selenic acid as the donor of selenium element, and the selenium element exists in the form of free acid, which is easier to be directly absorbed by the thallus without dissociation.

[0020] As an implementation mode, the culture time is 8 - 12 h. As another implementation mode, the culture time is 8 - 10 h. As an implementation mode, the upright branches of Caulerpa lentillifera are the upright branches after harvesting Caulerpa lentillifera.

[0021] The present invention discovers that long-term selenium-enriched culture is not conducive to the growth of Caulerpa lentillifera, and there is no difference in the distribution of selenium element between the upright branches and stolons of Caulerpa lentillifera. Considering that the upright branches of Caulerpa lentillifera are the commercial parts, and the selenium element in the stolons is meaningless for the production of selenium-enriched Caulerpa lentillifera products, the present invention aims at the characteristic that the upright branches of Caulerpa lentillifera can still survive and grow after harvesting, and performs selenium-enriched culture on the harvested upright branches in water with specific selenium element, which can improve the absorption rate of the upright branches of Caulerpa lentillifera, and selenium-enriched upright branches of Caulerpa lentillifera (selenium content ≥ 0.5 mg / kg) can be obtained within a short time (8 - 24 h), which not only saves costs but also improves efficiency. Compared with the traditional cultivation method of selenium-enriched agricultural products, the method provided by the present invention is simple to operate and suitable for industrial operation.

[0022] As an implementation mode, the culture temperature is 24 - 28 °C, and the light intensity is 25 - 35 μmol / m 2 ·s. As another implementation mode, the culture temperature is 26 °C, and the light intensity is 30 μmol / m2 ·s。

[0023] To further illustrate the present invention, a method for rapidly cultivating upright branches of Caulerpa lentillifera rich in selenium will be described in detail below in conjunction with embodiments and drawings, but they should not be construed as limiting the scope of protection of the present invention.

[0024] Example 1 A square grid frame was used as the cultivation tool, and a pool that could hold 1.5 m 3 of water body was filled with disinfected seawater, and 0.25 mL of nutrient salt mother liquor and 375 mL were added to each liter of water; the nutrient salt mother liquor was composed of components with the following concentrations: ammonium chloride 10.27 g / L, sodium nitrate 63.75 g / L, and sodium dihydrogen phosphate 4.8 g / L.

[0025] The temporarily cultured Caulerpa lentillifera was selected and weighed. A selenic acid group and a control group without adding selenic acid were set up. 400 g of algal bodies were placed in each group, and 3 biological replicates were set up in each group. The selenic acid group was: adding selenic acid mother liquor (10 mg / mL) to the water body to make the selenium element concentration in the water body 0.1 mg / L. Culture conditions: Continuously culture for 8 days, and observe the changes in pH, temperature, and salinity every day. After 8 days, take out for index determination.

[0026] Before the start of the experiment, the fresh weight of the algal bodies was weighed with a balance and recorded as W0; after the breeding ended, the surface moisture was blotted dry with absorbent paper and then the fresh weight of the algal bodies was weighed with a balance and recorded as W t . When measuring the fresh weight of the algal bodies, the algal frame for culturing the algal bodies was vertically static for 10 minutes and then measured, so that the water on the surface of the algal bodies naturally dripped, preventing the water content from affecting the measurement data. Calculate the specific growth rate (%) of the algal bodies, as shown in formula I: Specific growth rate = [ln(W t / W0)] / t × 100% Formula I; In formula I, W0 is the initial fresh weight (g); Wt is the fresh weight after breeding (g); t is the experimental period (d).

[0027] Before and after cultivation, 10 complete Caulerpa lentillifera were taken, placed together with a 20 cm standard ruler for photographing and recording, and ImageJ software was used to measure the length of the stolons of the algal bodies, the number of upright branches, the average length of the upright branches, and the distribution density of the upright branches (the number of upright branches on every 10 cm of stolons).

[0028] For each group, 10 g of stolons and 10 g of upright branches were taken, the surface moisture was blotted dry with blotting paper, weighed with a balance and recorded, then put into a sampling bag and stored frozen in a refrigerator. The selenium content in the samples was determined according to GB 5009.93-2017 National Food Safety Standard - Determination of Selenium in Foods. The thalli were distributed into grid frames and placed in water, and a temperature and light intensity recorder was used to record the changes in temperature and light intensity during the cultivation process.

[0029] The above determination results are shown in Figures 1 to 3 .

[0030] As Figure 1 shown, the average daily specific growth rate of Caulerpa lentillifera cultured with selenium enrichment was 3.07±1.17%, while that of the control group without added selenic acid was 3.81±0.38%, slightly higher than that of Caulerpa lentillifera cultured with selenium enrichment, but there was no significant difference between the two ( P >0.05).

[0031] As Figure 2 shown, after adding 0.1 mg / L selenic acid, there was no significant difference in the stolon length, the number of upright branches per individual thallus and the distribution density of upright branches before and after cultivation; however, the average length of the upright branches decreased extremely significantly. It is speculated that long-term selenium-enriched cultivation may inhibit the growth of thalli. Therefore, the selenium content in different parts of the thalli was further compared.

[0032] As Figure 3 shown (the same letters indicate no significant difference), after culturing with 0.1 mg / L selenic acid in the culture system for 8 days, the selenium content (dry weight) in the stolons was 0.33±0.07 mg / kg, and the selenium content (dry weight) in the upright branches was 0.34±0.06 mg / kg, with no significant difference between the two. This result shows that there is no difference in the distribution of selenium in the upright branches and stolons of Caulerpa lentillifera. Considering that the upright branches of Caulerpa lentillifera are the commercial part, the selenium in the stolons is meaningless for the production of selenium-enriched Caulerpa lentillifera products. Therefore, mature commercial upright branches can be selected as the selenium enrichment object in selenium-enriched aquaculture, which can not only save costs but also improve efficiency.

[0033] Example 2 An experiment was carried out in a 20 L plastic water bucket, and disinfected seawater (salinity measured at 31‰) was injected. Selenic acid mother liquor (10 mg / mL) was added to the water to make the selenium concentration in the water 0.05 mg / L, 0.1 mg / L and 0.2 mg / L. The upright branches after harvesting Caulerpa lentillifera were taken, and 3 groups of biological replicates were set up, with 80 g of upright branch commodities in each group. The culture conditions were 26 °C and the light was 30 μmol / m 2·s, add 0.25 mL of nutrient salt mother liquor per liter of water, and culture for a total of 24 h. Take 9 g of upright branch samples at the 1st h, 2nd h, 4th h, 6th h, 8th h, 12th h, and 24th h of the culture. Blot the surface moisture with absorbent paper, put it in the refrigerator for freezing preservation, and measure the selenium content. The results are shown in Figure 4 , where different letters indicate significant differences between groups at the same time ( P <0.05), 0.05, 0.1, and 0.2 represent the selenium element concentrations in the water body of 0.05 mg / L, 0.1 mg / L, and 0.2 mg / L, respectively.

[0034] The results show that after adding selenic acid at different concentrations, the selenium element content in the upright branches of each group generally increases gradually with the increase of the culture time. After 1 h of culture, no selenium content could be detected in the upright branches under low concentration (0.05 mg / L) and medium concentration (0.1 mg / L) conditions; during the culture from 4 to 6 h, under low concentration and medium concentration conditions, the selenium element content in the upright branches was about 0.3 mg / kg, and under high concentration (0.2 mg / kg) conditions, the selenium content in the upright branches was significantly higher than the other two groups; after 8 h of culture, the selenium element content in the upright branches under high concentration reached 0.5 mg / kg, and it could reach 1.2 mg / kg at 12 h; while the selenium content in the upright branches under low concentration and medium concentration conditions needed more than 12 h to reach 0.5 mg / kg.

[0035] When the true kelp in Japan is rich in selenium, it can reach a stable state in 6 h and achieve a good absorption rate. Different growth periods of plants have very different effects on the absorption of ions. For example, wolfberry can effectively and rapidly absorb various metal ions during early somatic cell occurrence. As the plant grows, the absorption of metal ions will decrease and will not always maintain a fast absorption rate. In this embodiment, when 0.2 mg / L of selenic acid is added at the beginning of the upright branches of Caulerpa lentillifera rich in selenium, the absorption rate is fast from 8 to 10 h, which also shows that the upright branches of Caulerpa lentillifera also have the ability to rapidly absorb selenium elements and have a strong adaptability to the selenium environment. In summary, in industrial production, after using the harvested commercial upright branches and culturing them in 0.2 mg / L of selenic acid for 8 h, the best selenium-rich sea grape products can be obtained.

[0036] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all embodiments. People can also obtain other embodiments according to this embodiment without creative efforts, and these embodiments all belong to the protection scope of the present invention.

Claims

1. A method for rapidly cultivating upright branches of Caulerpa lentillifera rich in selenium Caulerpa lentillifera ), characterized in that Comprising: Culturing the upright branches of Caulerpa lentillifera in a water body containing 0.15 - 0.25 mg / L of selenium element for 8 - 24 h to obtain selenium-enriched upright branches of Caulerpa lentillifera.

2. The method according to claim 1, characterized in that, The concentration of selenium element in the water body is 0.2 mg / L.

3. The method according to claim 1 or 2, characterized in that, The donor of the selenium element includes selenic acid.

4. The method according to claim 1, characterized in that The culturing time is 8 - 12 h.

5. The method according to claim 1 or 2, characterized in that, The water body includes seawater, nutrient salt mother liquor and the donor of selenium element; the volume ratio of the seawater to the nutrient salt mother liquor is 1000:0.2 - 0.3; the nutrient salt mother liquor includes components with the following concentrations: ammonium chloride 10.27 g / L, sodium nitrate 63.75 g / L, and sodium dihydrogen phosphate 4.8 g / L.

6. The method according to claim 5, characterized in that The volume ratio of the seawater to the nutrient salt mother liquor is 1000:0.

25.

7. The method according to claim 5, characterized in that, The salinity of the seawater is 30 - 32‰.

8. The method according to claim 1, wherein The temperature for culturing is 24~28°C, and the light intensity is 25~35 μmol / m 2 ·s.

9. The method according to claim 8, wherein The temperature of the cultivation is 26 °C, and the light intensity is 30 μmol / m 2 ·s.

10. The method according to claim 1, characterized in that, The upright branches of Caulerpa lentillifera are the upright branches after harvesting Caulerpa lentillifera.

Images