Cadmium-reducing and selenium-enriching biological purification method for crassostrea hongkongensis

Abstract

The invention belongs to the technical field of methods for purifying heavy metals in oyster bodies, and discloses a Crassostrea hongkongensis cadmium-reducing and selenium-enriching biological purification method, which comprises the following four steps: temporary culture of oysters, preparation of a nano-selenium solution, cadmium stress treatment and supply of nano-selenium. According to the method, nano-selenium is used for treatment under specific conditions, so that the content of cadmium in oyster bodies can be remarkably reduced, meanwhile, the content of selenium is increased, and no adverse effect is caused on the oysters. According to the method, only the nano-selenium solution with the specific concentration needs to be added into the aquaculture water body; the cadmium reducing effect is obvious: after 14 days of nano-selenium feeding treatment, the content of cadmium in the oyster body is obviously reduced; the selenium-rich effect is obvious: the selenium content in the treated oysters is obviously increased; the safety is high: the physiological indexes of the treated oysters are recovered to a normal level; operation is simple and convenient, and a new technical scheme is provided for safe production of oyster products.

Description

Technical Field

[0001] The invention belongs to the technical field of heavy metal purification methods in oysters, and more specifically, relates to a cadmium-reducing and selenium-enriching biological purification method for Hong Kong oysters. Background Art

[0002] With the intensification of environmental pollution, the accumulation of heavy metal cadmium (Cd) in the food chain has become a focus of public health concern. Oysters are typical representatives of cadmium accumulation in marine organisms. The accumulation of cadmium in their bodies not only affects food safety, but may also affect human health through the food chain. Hong Kong oysters (Crassostrea hongkongensis) are the main economic shellfish farmed along the coast of southern my country. They mainly live at the confluence of salt and fresh water and have long suffered from cadmium pollution.

[0003] Selenium is recognized by the world as an element that can improve human immunity and anti-tumor functions. It is an indispensable trace element for the human body. Since selenium cannot be synthesized in the human body, the human body mainly relies on the intake of selenium-rich foods to supplement selenium. At present, inorganic selenium or organic selenium is mainly used for feeding in the treatment of cadmium reduction and selenium enrichment of aquatic products, but these methods have the following technical defects: unsatisfactory treatment effect, low absorption efficiency, low conversion efficiency, and potential safety hazards. As a new type of selenium source, nano-selenium (SeNPs) has the following significant advantages: ultra-small particle size and large surface area, as well as unique morphological characteristics; it has functional characteristics such as resistance to pathogens, tumor inhibition, and immunity enhancement for the human body; it has high bioavailability and safety.

[0004] Studies have shown that SeNPs can easily pass through biological cell walls and reach the plasma membrane due to their nanoscale particle size (usually tens to hundreds of nanometers). At the same time, due to their high specific surface area, they increase the contact area with the cytoplasm and improve the absorption efficiency. SeNPs enter the cytoplasm of biological cells through aquaporins. This mode of transport that does not require energy and specific transport enzymes has a higher transport rate, and its absorption rate is about 1.7 times that of conventional selenium (Se(IV) and Se(VI)).

[0005] In the agricultural field, SeNPs have been widely used to supplement selenium in crops such as rice, peppers, Chinese cabbage, melons, and strawberries. They not only significantly increase the selenium content in the edible parts of crops, but also play an important role in enhancing the stress resistance of crops. However, the research on the application of SeNPs in the reduction of cadmium and selenium in aquatic products is still in its infancy, and it is urgent to develop a safe and efficient method for reducing cadmium and enriching oysters. Summary of the invention

[0006] In order to make up for the deficiencies in the prior art, the present invention proposes a biological purification method for reducing cadmium and enriching selenium in Hong Kong oysters.

[0007] The second object of the present invention is to provide the application of the above method in reducing cadmium and enriching selenium in Hong Kong oysters.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A cadmium-reducing and selenium-enriching biological purification method for Hong Kong oysters comprises adding a nano-selenium solution into a culture water body in which Hong Kong oysters live every day for more than 14 days, so that the final concentration of the nano-selenium solution in the culture water body in which Hong Kong oysters live is 10-20 μg / L.

[0010] Preferably, the biological purification method for reducing cadmium and enriching selenium in Hong Kong oysters comprises the following steps:

[0011] S1. Oyster temporary culture: After cleaning, the Hong Kong oysters were kept in water at 28°C and salinity at 20±1‰ for 7 days; water was changed and feeding was carried out at a fixed time every day;

[0012] S2. Preparation of nano-selenium solution: Prepare 0.2 g / L nano-selenium mother solution and mix well before use;

[0013] S3, cadmium stress treatment: after the Hong Kong oysters have completed the temporary culture in step S1, cadmium chloride solution is added to the culture water to make the cadmium concentration in the water reach 80 μg / L to start cadmium stress, and the stress time is 7 days;

[0014] S4. Nano-selenium feeding: After the cadmium stress ends, add the same volume of nano-selenium mother solution to the aquaculture water every day for 14 consecutive days.

[0015] More preferably, in the cadmium-reducing and selenium-enriching biological purification method for Hong Kong oysters, the final concentration of the nano-selenium solution in the aquaculture water where the Hong Kong oysters live is 20 μg / L.

[0016] The present invention also provides application of the method in reducing cadmium and enriching selenium in Hong Kong oysters.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The invention discloses a biological purification method for reducing cadmium and enriching selenium in Hong Kong oysters, comprising four steps of temporary oyster culture, preparation of nano-selenium solution, cadmium stress treatment and nano-selenium feeding. The method can significantly reduce the cadmium content in oysters and increase the selenium content at the same time by using nano-selenium for treatment under specific conditions, and has no adverse effects on oysters. The method of the invention only needs to add a nano-selenium solution of a specific concentration to the aquaculture water body; the cadmium reduction effect is significant: after 14 days of nano-selenium feeding treatment, the cadmium content in the oysters is significantly reduced; the selenium enrichment effect is significant: the selenium content in the oysters is significantly increased after treatment; high safety: the physiological indicators of the oysters are restored to normal levels after treatment; simple operation: a new technical solution is provided for the safe production of oyster products. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The box plot of the fatness (%) of Hong Kong oysters in each treatment group is shown. Among them, Cd0_Se0 is the control group, Cd80_Se0 is the cadmium stress group, Cd80_Se10 is the 10μg / L nano-selenium treatment group, and Cd80_Se20 is the 20μg / L nano-selenium treatment group; each point in the figure represents a single sample data, the thick black line in the box plot represents the median, the box represents the interquartile range, and the different lowercase letters (a, b) above the box plot represent the significant difference between the groups (P<0.05);

[0020] Figure 2 The figure shows the changes in cadmium and selenium content in Hong Kong oysters in different treatment groups; the left side of the figure shows the cadmium content (mg / kg), and the right side shows the selenium content (mg / kg); among them, Cd0_Se0 is the control group, Cd80_Se0 is the cadmium stress group, Cd80_Se10 is the 10μg / L nano-selenium treatment group, and Cd80_Se20 is the 20μg / L nano-selenium treatment group. Different lowercase letters (a, b, c) above the bar graph indicate significant differences between groups (P<0.05), and the error bars indicate standard errors. DETAILED DESCRIPTION

[0021] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below in conjunction with specific drawings and embodiments. In the embodiments, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0022] Example 1

[0023] A biological purification method for reducing cadmium and enriching selenium in Hong Kong oysters comprises the following steps:

[0024] S1. Temporary oyster culture: Select Hong Kong oysters with good vitality and moderate size, clean and remove surface impurities, put them into 50L rectangular water tanks, add 30L seawater to each tank, and put 25 oysters. Control the water temperature at 28℃ and salinity at 20±1‰, and culture for 7 days. Change water and feed at a fixed time every day.

[0025] S2. Preparation of nano-selenium solution: Weigh 1.961g of nano-selenium, use 100mL of pure water to prepare 0.2g / L nano-selenium mother solution, use ultrasonic cleaning machine to mix, store at 4℃ after packaging. Mix by ultrasonic for 10 minutes before use. Refresh the solution every three days.

[0026] S3. Cadmium stress treatment: After the temporary rearing is completed, cadmium chloride solution is added to the aquaculture water to make the cadmium concentration in the water reach 80μg / L. The stress time is 7 days.

[0027] S4. Nano-selenium feeding: After the cadmium stress ended, nano-selenium mother solution (final concentration of nano-selenium 20 μg / L) was added to the aquaculture water every day for 14 consecutive days.

[0028] Example 2

[0029] A biological purification method for reducing cadmium and enriching selenium in Hong Kong oysters comprises the following steps:

[0030] S1. Temporary oyster culture: Select Hong Kong oysters with good vitality and moderate size, clean and remove surface impurities, put them into 50L rectangular water tanks, add 30L seawater to each tank, and put 25 oysters. Control the water temperature at 28℃ and salinity at 20±1‰, and culture for 7 days. Change water and feed at a fixed time every day.

[0031] S2. Preparation of nano-selenium solution: Weigh 1.961g of nano-selenium, use 100mL of pure water to prepare 0.2g / L nano-selenium mother solution, use ultrasonic cleaning machine to mix, store at 4℃ after packaging. Mix by ultrasonic for 10 minutes before use. Refresh the solution every three days.

[0032] S3. Cadmium stress treatment: After the temporary rearing is completed, cadmium chloride solution is added to the aquaculture water to make the cadmium concentration in the water reach 80μg / L. The stress time is 7 days.

[0033] S4. Nano-selenium feeding: After the cadmium stress ended, nano-selenium mother solution (final concentration of nano-selenium 10 μg / L) was added to the aquaculture water every day for 14 consecutive days.

[0034] Test example

[0035] 1. Determination of oyster fatness

[0036] The total weight of the oysters was measured, and the shells and tissues were dried at 60 °C for 48 h to constant weight, and the weights of the dry shells and dry tissues were weighed separately.

[0037] Calculation of fatness: CI = dry tissue weight / (whole oyster weight - dry shell weight).

[0038] from Figure 1 It can be seen that the control group (Cd0_Se0) had the highest fatness, showing a normal growth state; the fatness of the cadmium stress group (Cd80_Se0) was significantly lower than that of the control group, indicating that cadmium stress had a significant inhibitory effect on oyster growth; the fatness of the 10μg / L nano-selenium treatment group (Cd80_Se10) was similar to that of the cadmium stress group, indicating that the treatment effect of this concentration was not obvious; the fatness of the 20μg / L nano-selenium treatment group (Cd80_Se20) was significantly higher than that of the cadmium stress group, close to the level of the control group, indicating that this concentration of nano-selenium treatment can effectively improve the negative impact of cadmium stress on oyster growth.

[0039] The figure confirms that 20 μg / L is the optimal treatment concentration, at which the inhibitory effect of cadmium stress on the growth of Hong Kong oysters can be effectively alleviated.

[0040] 2. Determination of heavy metal content: According to GB 5009.268-2016 method, ICP-OES was used to determine the concentrations of Se and Cd in dry soft tissues.

[0041] from Figure 2 It can be seen that cadmium stress significantly increased the cadmium content in oysters, while nano-selenium treatment can significantly reduce the accumulation of cadmium in oysters, and the 20μg / L nano-selenium treatment group had the most significant cadmium reduction effect. Selenium content: With the increase in the concentration of nano-selenium treatment, the selenium content in oysters gradually increased, among which the 20μg / L nano-selenium treatment group had the most significant selenium enrichment effect. This figure intuitively shows that the present invention can achieve the dual effects of cadmium reduction and selenium enrichment in Hong Kong oysters by using nano-selenium treatment.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A biological purification method for reducing cadmium and enriching selenium in Hong Kong oysters, characterized in that: The nano-selenium solution is added to the aquaculture water of the Hong Kong oysters every day for more than 14 days, so that the final concentration of the nano-selenium solution in the aquaculture water of the Hong Kong oysters is 10-20 μg / L.

2. The cadmium-reducing and selenium-enriching biological purification method for Hong Kong oysters according to claim 1 is characterized in that: The following steps are involved: S1. Oyster temporary culture: After cleaning, the Hong Kong oysters were kept in water at 28°C and salinity at 20±1‰ for 7 days; water was changed and feeding was carried out at a fixed time every day; S2. Preparation of nano-selenium solution: Prepare 0.2 g / L nano-selenium mother solution and mix well before use; S3, cadmium stress treatment: after the Hong Kong oysters have completed the temporary culture in step S1, cadmium chloride solution is added to the culture water to make the cadmium concentration in the water reach 80 μg / L to start cadmium stress, and the stress time is 7 days; S4. Nano-selenium feeding: After the cadmium stress ends, add the same volume of nano-selenium mother solution to the aquaculture water every day for 14 consecutive days.

3. The cadmium-reducing and selenium-enriching biological purification method for Hong Kong oysters according to claim 1 is characterized in that: The final concentration of the nano-selenium solution in the aquaculture water where Hong Kong oysters live is 20 μg / L.

4. Application of the method according to any one of claims 1 to 3 in reducing cadmium and enriching selenium in Hong Kong oysters.

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