CN111235060A - Method for improving enzymatic activity of glutathione peroxidase of lactic acid bacteria - Google Patents

Abstract

The invention provides a method for improving the enzymatic activity of lactic acid bacteria glutathione peroxidase, which comprises the following steps: step 1, activating and culturing lactic acid bacteria to obtain lactic acid bacteria liquid; and 2, inoculating the lactobacillus bacterial liquid into a liquid culture medium containing sodium selenite, and carrying out salt stress or heat stress selenium-enriched culture. According to the invention, sodium selenite is used for selenium-enriched culture of lactic acid bacteria, and after the lactic acid bacteria are subjected to salt stress or heat stress selenium-enriched culture, the activity of glutathione peroxidase in the lactic acid bacteria is improved.

Description

A kind of method for improving lactic acid bacteria glutathione peroxidase enzyme activity

technical field

The invention relates to glutathione peroxidase, in particular to a method for improving the enzymatic activity of lactic acid bacteria glutathione peroxidase.

Background technique

Glutathione peroxidase (GSH-Px) is an important selenium-containing peroxidase in vivo. The active center of GSH-Px is selenocysteine, and its main function is to synergize with vitamins to protect cells from peroxide damage and remove harmful free radicals in the body. An important component of the protective system. GSH-Px can catalyze reduced glutathione (GSH) into oxidized glutathione (GSSG), reduce toxic peroxides to non _- toxic hydroxyl _compounds , and promote the decomposition of H2O2, thereby Protects the structure and function of cell membranes from interference and damage by peroxides. GSH-Px mainly includes four kinds: cytoplasmic GSH-Px, plasma GSH-Px, phospholipid hydroperoxide GSH-Px and gastrointestinal specific GSH-Px.

However, the enzymatic activity of the existing glutathione peroxidase is generally low, therefore, it is of great significance to improve the activity of glutathione peroxidase.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the present invention provides a method for improving the enzyme activity of lactic acid bacteria glutathione peroxidase. The method is simple and easy to implement and has remarkable effect, and solves the problem that the enzyme activity of the existing glutathione peroxidase is generally low.

The present invention is achieved through the following technical solutions:

A method for improving the enzymatic activity of lactic acid bacteria glutathione peroxidase, comprising the following steps:

Step 1, activating and culturing the lactic acid bacteria to obtain a lactic acid bacteria liquid;

Step 2, inoculate the lactic acid bacteria liquid into a liquid medium containing sodium selenite, and culture at a constant temperature of 37°C.

Preferably, in step 2, the concentration of sodium selenite in the liquid medium containing sodium selenite is 20-160 μg/mL.

Preferably, in step 2, the liquid medium also contains NaCl.

Further, the mass concentration of NaCl in the liquid medium is 0.4%-0.9%.

Preferably, in step 2, the lactic acid bacteria liquid is first inoculated into the MRS liquid medium, cultivated at a constant temperature of 37 ° C to logarithmic phase, and then subjected to heat stress treatment, and then the sodium selenite solution is added to the MRS liquid medium, Incubate at a constant temperature of 37°C.

Further, the temperature of the heat stress treatment is 45-55°C.

Preferably, step 1 is specifically as follows: injecting the MRS broth culture medium after high temperature and high pressure sterilization into the lactic acid bacteria freeze-drying tube, blowing with a pipette to fully dissolve the lactic acid bacteria into a bacterial suspension; Cultivated under specified conditions, and after successful activation, the strains were inoculated into MRS broth medium, and cultured at 37°C in a constant temperature incubator for continuous activation for three generations.

Compared with the prior art, the present invention has the following beneficial technical effects:

In the present invention, sodium selenite is used for selenium-enriched cultivation of lactic acid bacteria, and the enzyme activity of glutathione peroxidase is measured. It is found through research that after selenium-enriched cultivation of lactic acid bacteria, the enzymatic activity of glutathione peroxidase in lactic acid bacteria can be obtained. The GSH-Px activity of some strains of Lactobacillus rhamnosus, Lactobacillus reuteri and Lactobacillus acidophilus was significantly improved. This may be because Se is an essential element for the synthesis of selenocysteine in the catalytic site of GSH-Px, and the supplementation of selenium can increase the expression of selenocysteine, thereby enhancing the GSH-Px enzyme active.

Further, the glutathione peroxidase enzyme activity in lactic acid bacteria was further improved by salt stress combined with selenium-enriched culture, probably because a certain amount of salt concentration can promote selenium enrichment of lactic acid bacteria.

Furthermore, the selenium-enriched culture under heat stress further improved the intracellular GSH-Px activity of lactic acid bacteria. Heat stress may induce lactic acid bacteria to produce heat shock proteins, which increases the activity of some enzymes.

Description of drawings

Fig. 1 is the GSH-Px activity of seven selenium-enriched lactic acid bacteria;

Fig. 2 is the GSH-Px activity of Lactobacillus rhamnosus cultivated under different concentrations of sodium selenite;

Figure 3 is the GSH-Px activity of Lactobacillus acidophilus cultivated under different concentrations of sodium selenite;

Figure 4 is the GSH-Px activity of Lactobacillus reuteri cultivated under different concentrations of sodium selenite;

Figure 5 is the GSH-Px activity of Lactobacillus rhamnosus cultured under different salt concentrations;

Figure 6 is the GSH-Px activity of Lactobacillus acidophilus cultured under different salt concentrations;

Figure 7 is the GSH-Px activity of Lactobacillus reuteri cultured under different salt concentrations;

Figure 8 is the GSH-Px activity of Lactobacillus rhamnosus cultured under different temperature stress;

Figure 9 is the GSH-Px activity of Lactobacillus acidophilus cultured under different temperature stress;

Figure 10 is the GSH-Px activity of Lactobacillus reuteri cultured under different temperature stress.

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments, which are to explain rather than limit the present invention.

The present invention improves the method for lactic acid bacteria glutathione peroxidase enzyme activity, comprising the following steps:

Step 1, Activation of strains

Inject 0.3-0.5mL of MRS broth medium sterilized by high temperature and high pressure into the lactic acid bacteria freeze-drying tube, and gently blow with a pipette to dissolve it into a bacterial suspension. Aspirate the bacterial suspension, put it into 2 test tubes, and cultivate it under the specified conditions of the bacterial species. After the activation is successful, in order to improve the vitality of the bacterial species, inoculate each bacterial strain into the MRS broth medium, and keep it in a constant temperature incubator. Incubate at 37°C for 24-48h, and activate continuously for three generations.

Step 2, selenium-enriched culture of lactic acid bacteria

Prepare 0.17mg/mL sodium selenite solution and MRS liquid medium and pre-sterilize. When using, add sodium selenite solution to MRS liquid medium and dilute to the required concentration. Inoculate 1 mL of the above-mentioned three generations of bacterial liquid into the MRS liquid medium containing sodium selenite, add the bacterial liquid to the MRS liquid medium without selenium to cultivate as a control, and leave it at a constant temperature at 37 ° C and a pH value of 5.6 to 7.2. Cultivated for 24h.

The bacterial liquid obtained above was centrifuged at 5000 r/min for 4 min, and the bacterial cells were washed with physiological saline and then centrifuged at 10000 r/min for 20 min to wash off the culture medium, and repeated until the supernatant was colorless and transparent. The bacteria were resuspended in physiological saline, and the cells were broken by ultrasonic waves in an ice bath (intermittent 2s for each working 2s, output power 100w) for 10min, centrifuged at 4°C, 10000r/min for 15min, and the supernatant was collected, which is the intracellular extract of lactic acid bacteria, The intracellular extract was stored at -20°C for later use.

Step 3, GSH-Px activity assay

Glutathione peroxidase is a selenium-containing system that scavenges free radicals and inhibits free radical reactions in the body. It can catalyze the reaction of hydrogen peroxide and reduced glutathione. For hydrogen oxide, under the catalysis of GSH-Px, the content of GSH will decrease to a certain extent before and after the reaction, and the enzymatic activity of glutathione peroxidase is determined by the measured decomposition rate.

In step 2, NaCl can also be added to the MRS liquid medium in the selenium-enriched culture, so as to carry out the salt-stressed selenium-enriched culture. Alternatively, the bacterial broth was subjected to heat stress treatment before selenium-enriched cultivation.

Standard curve creation:

Prepare GSH standard solutions with concentrations of 0 μmol/L, 20 μmol/L, 40 μmol/L, 60 μmol/L, 80 μmol/L and 100 μmol/L (0 mL, 0.2 mL, 0.4 mL, 0.6 mL, 0.8 mL, 1.0 mL with a concentration of 1 mmol) /L GSH solution was added to 8 mL of metaphosphoric acid precipitant, and then distilled water to 10 mL). 2mL of standard solution was simultaneously added with 2.5mL of 0.32mol/L Na ₂ HPO ₄ solution and 0.5mL of DTNB solution. Measure the OD value at 423nm (within 5min). Plot a standard curve.

Preparation of crude enzyme solution:

Glutathione peroxidase is an enzyme in lactic acid bacteria cells, and the crude enzyme solution can be prepared by breaking cells. The method for the determination of the enzyme activity of the crude enzyme solution is the same as that for the preparation of the standard curve. For the control, the inactivated crude enzyme solution was used as the sample solution, and the specific activity unit of the enzyme was calculated according to formula (1).

Where: A is the slope of the GSH standard curve.

Example 1

Step 1, Activation of strains

Inject 0.3 mL of the MRS broth medium sterilized by high temperature and high pressure into the Lactobacillus rhamnosus freeze-dried tube, and gently blow it with a pipette to dissolve it into a bacterial suspension. Aspirate the bacterial suspension, put it into 2 test tubes, and cultivate it under the specified conditions of the bacterial species. After the activation is successful, in order to improve the vitality of the bacterial species, inoculate each bacterial strain into the MRS broth medium, and keep it in a constant temperature incubator. The cells were incubated at 37°C for 24h, and activated for three generations.

Step 2, Lactobacillus rhamnosus selenium-enriched culture

0.17mg/mL sodium selenite solution and MRS liquid medium were prepared and pre-sterilized. When using, the sodium selenite solution was added to the MRS liquid medium and diluted to a sodium selenite concentration of 20 μg/mL. Inoculate 1 mL of the above-mentioned three-generation Lactobacillus rhamnosus bacterial solution in the MRS liquid medium with a sodium selenite concentration of 20 μg/mL, and add the bacterial liquid to the MRS liquid medium without selenium to cultivate as a control, 37 ° C, pH Under the conditions of 5.6-7.2, the cells were incubated at a constant temperature for 24h.

The bacterial liquid obtained above was centrifuged at 5000 r/min for 4 min, and the bacterial cells were washed with physiological saline and then centrifuged at 10000 r/min for 20 min to wash off the culture medium, and repeated until the supernatant was colorless and transparent. The bacteria were resuspended in physiological saline, and the cells were broken by ultrasonic waves in an ice bath (intermittent 2s for each working 2s, output power 100w) for 10min, centrifuged at 4°C, 10000r/min for 15min, and the supernatant was collected, which is the intracellular extract of lactic acid bacteria, The intracellular extract was stored at -20°C for later use.

Example 2-7

In embodiment 2-7, Lactobacillus rhamnosus is replaced by Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus reuteri, Lactobacillus bulgaricus, Streptococcus thermophilus and Lactobacillus plantarum respectively, and other conditions are identical with embodiment 1 .

Examples 8-14

The sodium selenite concentration was adjusted to 40 μg/mL, 60 μg/mL, 80 μg/mL, 100 μg/mL, 120 μg/mL, 140 μg/mL, and 160 μg/mL, respectively, and other conditions were the same as in Example 1.

Examples 15-21

Lactobacillus rhamnosus was replaced by Streptococcus thermophilus, and the concentration of sodium selenite was adjusted to 40 μg/mL, 60 μg/mL, 80 μg/mL, 100 μg/mL, 120 μg/mL, 140 μg/mL, and 160 μg/mL, respectively. Other conditions are the same as in Example 1.

Examples 22-28

Replace Lactobacillus rhamnosus with Lactobacillus reuteri, and replace the concentration of sodium selenite with 40 μg/mL, 60 μg/mL, 80 μg/mL, 100 μg/mL, 120 μg/mL, 140 μg/mL, 160 μg/mL, respectively , other conditions are the same as in Example 1.

Example 29

Step 1, Activation of strains

Inject 0.3 mL of the MRS broth medium sterilized by high temperature and high pressure into the Lactobacillus rhamnosus freeze-dried tube, and gently blow it with a pipette to dissolve it into a bacterial suspension. Aspirate the bacterial suspension, put it into 2 test tubes, and cultivate it under the specified conditions of the bacterial species. After the activation is successful, in order to improve the vitality of the bacterial species, inoculate each bacterial strain into the MRS broth medium, and keep it in a constant temperature incubator. The cells were incubated at 37°C for 24h, and activated for three generations.

Step 2, Lactobacillus rhamnosus salt stress selenium enrichment culture

Inoculate 1 mL of lactic acid bacteria seed solution that was activated for three generations and then cultured to logarithmic phase in six groups with NaCl concentration of 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% and sodium selenite concentration of 20 μg/ In the MRS liquid medium of mL, the blank group was MRS medium containing 20 μg/mL sodium selenite without NaCl, and incubated at 37°C for 48 h. Two parallel samples were made for each group, and the operation was repeated.

The bacterial liquid obtained above was centrifuged at 5000 r/min for 4 min, and the bacterial cells were washed with physiological saline and then centrifuged at 10000 r/min for 20 min to wash off the culture medium, and repeated until the supernatant was colorless and transparent. The bacteria were resuspended in physiological saline, and the cells were broken by ultrasonic waves in an ice bath (intermittent 2s for each working 2s, output power 100w) for 10min, centrifuged at 4°C, 10000r/min for 15min, and the supernatant was collected, which is the intracellular extract of lactic acid bacteria, The intracellular extract was stored at -20°C for later use.

Example 30

The Lactobacillus rhamnosus was replaced with Lactobacillus acidophilus, and the others were the same as in Example 29.

Example 31

The Lactobacillus rhamnosus was replaced by Lactobacillus reuteri, and the others were the same as in Example 29.

Example 32

Step 1, Activation of strains

Inject 0.3 mL of the MRS broth medium sterilized by high temperature and high pressure into the Lactobacillus rhamnosus freeze-dried tube, and gently blow it with a pipette to dissolve it into a bacterial suspension. Aspirate the bacterial suspension, put it into 2 test tubes, and cultivate it under the specified conditions of the bacterial species. After the activation is successful, in order to improve the vitality of the bacterial species, inoculate each bacterial strain into the MRS broth medium, and keep it in a constant temperature incubator. The cells were incubated at 37°C for 24h, and activated for three generations.

Step 2, Lactobacillus rhamnosus heat stress selenium enrichment culture

Inoculate 1 mL of MRS liquid medium with the third generation of bacteria, incubate at 37 °C for 6 h to logarithmic phase, and stress them in a water bath at 45 °C, 47 °C, 49 °C, 51 °C, 53 °C, and 55 °C for 15 min, and then incubate them in a water bath. 2mL of 0.17mg/mL sodium selenite solution was added therein, so that the concentration of sodium selenite in the medium was 20μg/mL. Two parallel experiments were performed in each group and a blank group was set as a control. Incubate at 37°C for 48h.

The bacterial liquid obtained above was centrifuged at 5000 r/min for 4 min, and the bacterial cells were washed with physiological saline and then centrifuged at 10000 r/min for 20 min to wash off the culture medium, and repeated until the supernatant was colorless and transparent. The bacteria were resuspended in physiological saline, and the cells were broken by ultrasonic waves in an ice bath (intermittent 2s for each working 2s, output power 100w) for 10min, centrifuged at 4°C, 10000r/min for 15min, and the supernatant was collected, which is the intracellular extract of lactic acid bacteria, The intracellular extract was stored at -20°C for later use.

Example 33

Replacing Lactobacillus rhamnosus with Lactobacillus acidophilus was the same as in Example 32.

Example 34

The Lactobacillus rhamnosus was replaced with Lactobacillus reuteri, and the others were the same as in Example 32.

(1) Determination of glutathione peroxidase under selenium-enriched culture

Enzyme activity was measured for Examples 1-7, Lactobacillus casei (LC), Lactobacillus rhamnosus (LCR), Lactobacillus bulgaricus (LB), Lactobacillus plantarum (LP), Streptococcus thermophilus (ST), Luo The enzymatic activities of the cell-free extracts of Lactobacillus acidophilus (LR) and Lactobacillus acidophilus (LA) blank groups were 8.049U/mg, 8.808U/mg, 6.554U/mg, 7.233U/mg, 8.622U/mg, respectively. mg, 7.579U/mg, 8.206U/mg, and the enzyme activities in the selenium-added group were 8.145U/mg, 10.034U/mg, 7.494U/mg, 7.667U/mg, 8.694U/mg, 10.217U/mg, 9.931U/mg. The GSH-Px activity of seven lactobacillus strains was increased after selenium enrichment, among which Lactobacillus rhamnosus, Lactobacillus reuteri and Lactobacillus acidophilus increased significantly. It can be seen that selenium-enriched culture can improve the GSH-Px activity of lactic acid bacteria, which may be because Se is an essential element for the synthesis of selenocysteine in the catalytic site of GSH-Px, and the supplementation of selenium element can make selenocysteine The expression of amino acid increased, thereby enhancing the GSH-Px enzyme activity.

(2) Effects of different concentrations of sodium selenite and selenium-enriched culture on the content of glutathione peroxidase

The enzymatic activities of Example 1 and Examples 8-14 were measured, and it can be seen from Figure 2 that for Lactobacillus rhamnosus, when the concentration of sodium selenite was 20 μg/mL, 40 μg/mL, 60 μg/mL, 80 μg/mL, At 100μg/mL, 120μg/mL, 140μg/mL, and 160μg/mL, the GSH-Px activities were 10.034U/mg, 14.228U/mg, 15.621U/mg, 15.795U/mg, 14.999U/mg, 14.469U, respectively /mg, 13.791U/mg, 12.990U/mg. When the concentration of sodium selenite was increased to 80 μg/mL, the activity of GSH-Px was the highest.

The enzymatic activities of Examples 2 and 15-21 were measured, and it can be seen from Figure 3 that for Lactobacillus acidophilus, when the sodium selenite concentration was 20 μg/mL, 40 μg/mL, 60 μg/mL, 80 μg/mL, 100 μg/mL , 120μg/mL, 140μg/mL, 160μg/mL, the GSH-Px activities were 9.930U/mg, 12.177U/mg, 12.811U/mg, 14.137U/mg, 14.999U/mg, 14.519U/mg, 13.368U/mg, 12.058U/mg. With the increase of sodium selenite concentration, the activity of GSH-Px increased first and then decreased. When the concentration of sodium selenite increased to 100 μg/mL, the activity of GSH-Px was the highest.

The enzymatic activities of Examples 3 and 22-28 were measured, and it can be seen from Figure 4 that for Lactobacillus reuteri, when the concentration of sodium selenite was 20 μg/mL, 40 μg/mL, 60 μg/mL, 80 μg/mL, 100 μg/mL mL, 120μg/mL, 140μg/mL and 160μg/mL, the GSH-Px activities were 10.217U/mg, 10.714U/mg, 13.061U/mg, 13.554U/mg, 15.905U/mg, 15.768U/mg, respectively , 13.465U/mg, 11.413U/mg. With the increase of concentration, the activity of GSH-Px increased first and then decreased. When the concentration of sodium selenite increased to 100 μg/mL, the activity of GSH-Px was the highest.

It is inferred that for selenium-containing lactic acid bacteria, the addition of selenium has a certain relationship with the GSH-Px activity, that is, the GSH-Px activity of lactic acid bacteria increases with the increase of Se addition concentration within a certain range, and when the sodium selenite increases When the concentration increased to a certain extent, the activity of GSH-Px decreased slightly. It may be that the increase of sodium selenite gradually promotes the increase of selenocysteine. When the concentration of sodium selenite is too high, the synthesis of selenocysteine is inhibited, so that the GSH-Px activity will not increase continuously. .

(3) The effect of salt stress on the activity of glutathione peroxidase

The enzyme activity was measured in Example 29, and it can be seen from Figure 5 that for Lactobacillus rhamnosus, when the salt mass concentration was 0.4%, 0.5%, 0.6%, 0.7%, 0.8% and 0.9%, the GSH-Px activities were respectively 10.372U/mg, 13.041U/mg, 14.692U/mg, 15.533U/mg, 12.185U/mg, 11.941U/mg. With the increase of salt concentration, the activity of GSH-Px increased first and then decreased significantly. When the salt concentration increased to 7%, the activity of GSH-Px was the highest.

The enzyme activity measurement of Example 30 was carried out. It can be seen from Figure 6 that for Lactobacillus acidophilus, when the salt concentration was 0.4%, 0.5%, 0.6%, 0.7%, 0.8% and 0.9%, the GSH-Px activity was 10.628U, respectively /mg, 11.429U/mg, 14.836U/mg, 13.298U/mg, 11.589U/mg, 10.392U/mg. With the increase of salt concentration, the activity of GSH-Px increased first and then decreased gradually. When the salt concentration increased to 6%, the activity of GSH-Px was the highest.

The enzymatic activity of Example 31 was measured, and it can be seen from Figure 7 that for Lactobacillus reuteri, when the salt concentration was 0.4%, 0.5%, 0.6%, 0.7%, 0.8% and 0.9%, the GSH-Px activity was 10.782, respectively U/mg, 11.998U/mg, 13.519U/mg, 13.007U/mg, 12.426U/mg, 11.160U/mg. With the increase of salt concentration, the activity of GSH-Px increased first and then decreased slowly. When the salt concentration increased to 6%, the activity of GSH-Px was the highest.

The enrichment of selenium in salt-stressed lactic acid bacteria is achieved by changing its osmotic pressure. When the osmotic pressure increases, the lactic acid bacteria maintain the normal osmotic pressure of the cells by absorbing compatible substances; when the extracellular osmotic pressure decreases, the lactic acid bacteria keep the osmotic pressure at a normal level by releasing the absorbed compatible substances , but different lactic acid bacteria absorb compatible substances in different ways and mechanisms. The research of the present invention shows that a certain amount of salt concentration can promote the selenium enrichment of lactic acid bacteria, which leads to an increase in the synthesis of selenocysteine, thereby increasing the activity of lactic acid bacteria GSH-Px.

(3) Effects of heat stress on the activity of glutathione peroxidase

The enzyme activity of Example 32 was measured, and it can be seen from Figure 8 that for Lactobacillus rhamnosus, when the heat stress temperature was 45°C, 47°C, 49°C, 51°C, 53°C, and 55°C, the GSH-Px activities were 11.472U/mg, 12.744U/mg, 13.423U/mg, 16.086U/mg, 13.665U/mg, 12.188U/mg. When the temperature was increased to 51 °C, the GSH-Px activity was the highest.

The enzyme activity assay of Example 33 shows that for Lactobacillus acidophilus, when the heat stress temperature is 45 ℃, 47 ℃, 49 ℃, 51 ℃, 53 ℃, 55 ℃, the GSH-Px activity is 12.439 U/mg, 13.004U/mg, 11.173U/mg, 10.474U/mg, 9.622U/mg, 9.388U/mg. With the increase of stress temperature, the activity of GSH-Px increased first and then decreased, and decreased gradually. When the temperature increased to 47℃, the activity of GSH-Px was the highest.

The enzyme activity of Example 34 was measured, and it can be seen from Figure 10 that for Lactobacillus reuteri, when the heat stress temperature was 45°C, 47°C, 49°C, 51°C, 53°C, and 55°C, the GSH-Px activities were 12.965U/mg, 16.088U/mg, 15.918U/mg, 11.923U/mg, 11.671U/mg, 10.161U/mg. With the increase of stress temperature, the activity of GSH-Px increased first and then decreased, and the decreasing trend was obvious at 51℃. When the temperature increased to 47℃, the activity of GSH-Px was the highest.

It can be seen that heat stress may induce lactic acid bacteria to produce heat shock proteins and increase the activity of some enzymes. In this study, heat stress promoted the increase of GSH-Px activity.

Claims (7)

1. a method for improving lactic acid bacteria glutathione peroxidase enzyme activity, is characterized in that, comprises the following steps: Step 1, activating and culturing the lactic acid bacteria to obtain a lactic acid bacteria liquid; Step 2, inoculate the lactic acid bacteria liquid into a liquid medium containing sodium selenite, and culture at a constant temperature of 37°C. 2. the method for improving lactic acid bacteria glutathione peroxidase enzyme activity according to claim 1 is characterized in that, in step 2, the concentration of sodium selenite in the liquid culture medium containing sodium selenite is 20 -160 μg/mL. 3. the method for improving lactic acid bacteria glutathione peroxidase enzyme activity according to claim 1, is characterized in that, in step 2, also contains NaCl in liquid culture medium. 4. The method for improving the glutathione peroxidase activity of lactic acid bacteria according to claim 3, wherein the mass concentration of NaCl in the liquid culture medium is 0.4%-0.9%. 5. the method for improving lactic acid bacteria glutathione peroxidase enzyme activity according to claim 1, is characterized in that, in step 2, first lactic acid bacteria bacterial liquid is inoculated in MRS liquid culture medium, at 37 ℃ of constant temperature cultures to After the logarithmic phase, heat stress treatment was performed, and then sodium selenite solution was added to the MRS liquid medium for static culture at a constant temperature of 37°C. 6 . The method for improving the glutathione peroxidase activity of lactic acid bacteria according to claim 5 , wherein the temperature of heat stress treatment is 45-55° C. 7 . 7. the method that improves lactic acid bacteria glutathione peroxidase enzyme activity according to claim 1, is characterized in that, step 1 is specially: the MRS broth culture medium after high temperature and high pressure sterilization is injected into lactic acid bacteria freeze-drying In the tube, pipette with a pipette to fully dissolve the lactic acid bacteria into a bacterial suspension; cultivate the bacterial suspension under the specified conditions of the bacterial species, and after successful activation, inoculate the bacterial strain into the MRS broth medium, in a constant temperature incubator The cells were cultured at 37°C and continuously activated for three generations.

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