A probiotic preparation for poultry prepared by fermenting with selenium-tolerant Lactobacillus plantarum from ducks

Abstract

The present invention provides a probiotic preparation for poultry prepared by fermenting Lactobacillus plantarum from ducks resistant to selenium, which is prepared by inoculating Lactobacillus plantarum from ducks with a high selenium ion load into a culture medium for fermentation; the Lactobacillus plantarum from ducks with a high selenium ion load has a preservation number of CGMCC No. 30182. The high selenium-loaded Lactobacillus plantarum from ducks obtained by domestication and screening by the method of gradually increasing the selenium ion concentration in the culture medium in the present invention, and the postbiotics prepared therefrom contain small peptides, small molecule organic acids, digestive enzymes, etc. Because it is rich in targeted antibacterial peptides, it has obvious inhibitory effects on harmful bacteria such as Escherichia coli, Salmonella, and Riemerella anatipestifer. Other bioactive substances such as digestive enzymes contained therein can promote the growth and development of poultry and improve the product quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of biopreparation, and particularly relates to a probiotic preparation for poultry prepared by fermenting selenium-tolerant duck-derived Lactobacillus plantarum. Background Art

[0002] In poultry farming, it is common for the growth performance and immune health of animals to decline due to selenium deficiency in feed. Therefore, in order to improve the absorption and metabolism, growth and development, immunity, and clinical health functions of animals, it is necessary to meet the selenium needs of animals and prevent the occurrence of selenium deficiency, which is also an important measure in modern livestock production. At present, according to the different forms of selenium metabolism in organisms, selenium supplements are divided into inorganic selenium and organic selenium.

[0003] Inorganic selenium refers to inorganic selenium compounds, including selenides Se 4+ (selenite), selenates Se 6+ (selenate), Se 0 (elemental selenium), and Se 2- (selenium compounds), etc. Sodium selenite is the most widely used and generally accepted inorganic selenium additive in the world at present. However, the selenite ions in inorganic selenium are easily oxidized, with extremely low biological absorption and utilization rate, and can be toxic to the body, resulting in poor selenium deposition and storage capacity in the body. Therefore, it may cause potential toxic effects on animals and also pollute the environment. Organic selenium refers to the organic compounds and selenium-containing bioactive macromolecules produced by combining selenium and amino acids through biological metabolic activities in organisms. Therefore, compared with inorganic selenium, organic selenium has the advantages of low toxic and side effects, high efficiency at low doses, and being easily absorbed and utilized by animal bodies, and also has significant advantages in enhancing the antioxidant performance, immune function, and resistance to heat stress of the body. Therefore, exploring a method that can not only promote the normal growth and development of poultry but also maintain intestinal health and increase selenium absorption rate is of great significance for the precise nutrition of poultry farming and maintaining a good ecological cycle. Summary of the Invention

[0004] The present invention provides a probiotic preparation for poultry prepared by fermenting selenium-tolerant duck-derived Lactobacillus plantarum, thus making up for the deficiencies of the prior art.

[0005] The present invention first provides a probiotic preparation for poultry prepared by fermenting selenium-tolerant duck-derived Lactobacillus plantarum, which is prepared by inoculating duck-derived Lactobacillus plantarum with high selenium ion loading (Se 4+ ) into a culture medium for fermentation;

[0006] The said high selenium ion loading (Se 4+The duck-derived Lactobacillus plantarum of ), as specifically described in the embodiments of the present invention, is Lactobacillus plantarum (LP), which was deposited on March 28, 2024, at the General Microbiology Center of the China Committee for Culture Collection of Microorganisms, Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, with the deposit number CGMCC No. 30182.

[0007] For the fermentation mentioned above, the preferred composition of the culture medium is as follows: peptone 10 g / L, beef powder 10 g / L, yeast powder 5 g / L, glucose 20 g / L, magnesium sulfate 0.1 g / L, sodium acetate 5 g / L, ammonium citrate 2 g / L, dipotassium hydrogen phosphate 2 g / L, manganese sulfate 0.05 g / L, Tween 80 1 g / L, and the pH value is 6.2 ± 0.2.

[0008] The culture temperature is: 35.5 - 38.5 °C, preferably 37 °C; the culture time is 20 - 27 h, preferably 24 h.

[0009] The present invention also provides a small peptide with antibacterial effect, and the small peptide is isolated and prepared from the above-mentioned probiotic preparation.

[0010] The amino acid sequence of the small peptide is SEQ ID NO: 1 or SEQ ID NO: 2.

[0011] The avian probiotic preparation provided by the present invention can be used to prepare antibacterial products or feed additives to promote the growth and development of poultry.

[0012] The present invention provides a feed for livestock and poultry breeding, and the feed contains the above-mentioned avian probiotic preparation.

[0013] The method of gradually increasing the concentration of selenium ions (Se 4+ ) in the culture medium adopted in the present invention is used to domesticate and screen the high-selenium-loaded duck-derived Lactobacillus plantarum. It not only has the probiotic advantages of duck-derived Lactobacillus plantarum, but also can improve the intestinal selenium absorption rate and reduce the pollution of selenium ions (Se 4+ ) to the environment. At the same time, the high-selenium-loaded duck-derived Lactobacillus plantarum obtained by domestication and breeding produces more postbiotics, containing small peptides (antibacterial peptides), small molecule organic acids, digestive enzymes, etc. Due to the rich targeted antibacterial peptides, it has obvious inhibitory effects on harmful bacteria such as Escherichia coli, Salmonella, and Riemerella anatipestifer. Other bioactive substances such as digestive enzymes can promote the growth and development of poultry and improve the product quality. Description of the Drawings

[0014] Figure 1 : Diagram showing the effect of high-selenium-loaded ion domestication on the growth of Lactobacillus plantarum,

[0015] Figure 2: Effect diagram of high-load selenium ion domestication on selenium content of Lactobacillus plantarum

[0016] Figure 3 : Secondary mass spectrometry diagram of PTGGTPTSDHAATDKVNLNTADVAALQTLS sequence

[0017] Figure 4 : Secondary mass spectrometry diagram of STGVTLADGGEGTSEAFLANQRGGRWEYAM sequence

[0018] Figure 5 : Small peptide structure diagram of PTGGTPTSDHAATDKVNLNTADVAALQTLS sequence

[0019] Figure 6 : Small peptide structure diagram of STGVTLADGGEGTSEAFLANQRGGRWEYAM sequence

[0020] Figure 7 、 8 、9: Effect of postbiotics of duck-derived Lactobacillus plantarum with high-load selenium ions on antibacterial effect

[0021] Figure 10 : Flow cytometry diagram of Escherichia coli (postbiotics addition amount 1:4)

[0022] Figure 11 : Flow cytometry diagram of Salmonella (postbiotics addition amount 1:4)

[0023] Figure 12 : Flow cytometry diagram of Riemerella anatipestifer (postbiotics addition amount 1:4)

[0024] Figure 13 : Morphological diagram of Escherichia coli inhibited by postbiotics of duck-derived Lactobacillus plantarum with high-load selenium ions (postbiotics addition amount 1:4)

[0025] Figure 14 : Morphological diagram of Riemerella anatipestifer inhibited by postbiotics of duck-derived Lactobacillus plantarum with high-load selenium ions (postbiotics addition amount 1:4)

[0026] Figure 15 : Effect of postbiotics of duck-derived Lactobacillus plantarum with high-load selenium ions on fatty acids in breast muscle of meat ducks Specific implementation mode

[0027] The present invention uses duck-derived Lactobacillus plantarum screened by enhanced domestication culture and capable of greatly enhancing the loading of selenium ions (Se 4+ ) as a strain to ferment and prepare a bacterial preparation. The prepared bacterial preparation is rich in functional antibacterial peptides, has the effects of inhibiting the reproduction of harmful bacteria and promoting their apoptosis, and at the same time has the effects of promoting growth and development, improving slaughter performance, improving meat quality, increasing the antioxidant capacity of the body, and improving intestinal mucosal immunity.

[0028] The fermenting strain used is Lactobacillus plantarum from ducks with high selenium load, which was deposited on March 28, 2024 at the General Microbiology Center of the China Committee for Culture Collection of Microorganisms, Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, with the deposit number of CGMCC No. 30182.

[0029] The specific composition of the culture medium used in the embodiments of the present invention is as follows: peptone 10 g / L, beef powder 10 g / L, yeast powder 5 g / L, glucose 20 g / L, magnesium sulfate 0.1 g / L, sodium acetate 5 g / L, ammonium citrate 2 g / L, dipotassium hydrogen phosphate 2 g / L, manganese sulfate 0.05 g / L, Tween 80 1 g / L, pH value 6.2 ± 0.2.

[0030] The culture temperature during the fermentation of Lactobacillus plantarum from ducks is 35.5 - 38.5 °C; the culture time is 20 - 27 h.

[0031] The present invention will be described in detail below in combination with specific implementation cases.

[0032] Example 1: Cultivation and domestication of Lactobacillus plantarum from ducks with high selenium load

[0033] Domestication was carried out by gradually increasing the Se 4+ concentration in the culture medium; after the domesticated strain was continuously cultured for several generations, comparisons were made with the Lactobacillus plantarum before domestication in terms of cell morphology, enzyme activity, small peptides, amino acids, antibacterial effect, etc., to further determine the property characteristics of the domesticated Lactobacillus plantarum and its ability to be stably passaged. Finally, Lactobacillus plantarum (LP) that can tolerate a high concentration of sodium selenite (280 mg / L) was domestically cultured and deposited on March 28, 2024 at the General Microbiology Center of the China Committee for Culture Collection of Microorganisms, Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, with the deposit number of CGMCC NO. 30182.

[0034] The domesticated Lactobacillus plantarum from ducks with selenium ions can have the ability to load selenium ions. When the selenium ion addition amount is 280.0 mg / L, the organic selenium content in the cells is 21.60 μg / L, which is greater than the selenium content of ordinary Lactobacillus plantarum from ducks ( Figure 1 , Figure 2 ).

[0035] Example 2: Preparation method and active ingredient analysis of postbiotics of Lactobacillus plantarum from ducks with high selenium load

[0036] 1) Preparation method of postbiotics: Inoculate Lactobacillus plantarum with the preservation number of CGMCC NO. 30182 into a culture medium for fermentation. The culture temperature is 35.5 - 38.5 °C, and the culture time is 20 - 27 h. After centrifuging the fermentation broth at 6000 r / min for 6 - 12 minutes, filter it with a 0.22 μm aqueous filter membrane, and the filtrate is the prepared postbiotic preparation. The specific composition of the culture medium is as follows: peptone 10 g / L, beef powder 10 g / L, yeast powder 5 g / L, glucose 20 g / L, magnesium sulfate 0.1 g / L, sodium acetate 5 g / L, ammonium citrate 2 g / L, dipotassium hydrogen phosphate 2 g / L, manganese sulfate 0.05 g / L, Tween 80 1 g / L, and the pH value is 6.2 ± 0.2.

[0037] 2) Analysis of postbiotic active ingredients: The amylase content in the postbiotics, which is the fermentation product of domesticated Lactobacillus plantarum from ducks, is 0.26 U / mL, an increase of 18.18% compared with that before domestication; the lipase content is 48.66 U / L, an increase of 29.24% compared with that before domestication; the small peptide content is 23.09 mg / mL, an increase of 8.45% compared with that before domestication; the L-lactic acid content is 17.45 mg / mL, an increase of 19.44% compared with that before domestication; the acetic acid content is 0.42 mg / mL, an increase of 13.51% compared with that before domestication; the propionic acid content is 0.22 mg / mL, an increase of 22.22%; the butyric acid content is 0.21 mg / mL, an increase of 31.25%.

[0038] Example 3: Analysis of small peptide sequences in postbiotics of Lactobacillus plantarum from ducks before and after domestication

[0039] 1) Small peptide sequence analysis method: Entrust a commercial company to conduct protein Shotgun identification and analysis on Lactobacillus plantarum from ducks and Lactobacillus plantarum from ducks with high selenium ion loading. The experimental method is to add an appropriate amount of 0.1% TFA to the sample, mix well, centrifuge at 20000 g for 5 min, take the supernatant, transfer it to a 10 KD ultrafiltration centrifugal tube, and centrifuge at 12000 g for 15 min. Add 200 μL of 0.1% TFA and centrifuge at 12000 g for 15 min, repeat 2 times, collect the filtrate, desalt it using a C18 StageTip, and vacuum dry it. After drying, dissolve the peptide segments with 0.1% FA, measure the peptide segment concentration, and prepare for LC-MS analysis. Take an appropriate amount of peptide segments from each sample and perform chromatographic separation using a nano-flow rate Easy nL C1200 chromatographic system (Thermo Scientific). After the sample is injected into the Trap Column, it undergoes gradient separation through the chromatographic analysis column, and the flow rate is 300 nl / min. After the peptide segments are separated, perform DDA (data-dependent acquisition) mass spectrometry analysis using a Q-Exactive HF-X mass spectrometer (Thermo Scientific). Search through the mass spectrometry database retrieval software MaxQuant 2.4.14.0.

[0040] 2) Small peptide sequence analysis results:

[0041] Figure 3 As shown, the amino acid sequence of the small peptide with antibacterial activity of postbiotics of Lactobacillus plantarum from duck before domestication is: PTGGTPTSDHAATDKVNLNTADVAALQTLS (SEQ ID NO:1), and the relative molecular mass is 2965.46. Figure 4 As shown, the amino acid sequence of the small peptide with antibacterial activity of postbiotics of Lactobacillus plantarum from duck with high selenium ion loading is: STGVTLADGGEGTSEAFLANQRGGRWEYAM (SEQ ID NO:2), and the relative molecular mass is 3130.44. Figure 5 It is the structural diagram of the small peptide with the amino acid sequence of SEQ ID NO:1; Figure 6 It is the structural diagram of the small peptide with the amino acid sequence of SEQ ID NO:2.

[0042] 3) Analysis of the antibacterial effect of small peptides:

[0043] After synthesizing the small peptides with the sequences of SEQ ID NO:1 and SEQ ID NO:2, they were diluted with MRS medium to make the total volume of the solution the same as the initial fermentation volume. Respectively, the same content of small peptides and harmful bacteria were taken for the growth test of inhibiting harmful bacteria in ducks (Escherichia coli, Riemerella anatipestifer, Salmonella) to verify the in vitro antibacterial activity of the artificially synthesized peptides against harmful bacteria. After filtering and sterilizing the synthesized peptides through a 0.22μm water membrane, they were added to a 96-well plate. A medium with normal inoculation of harmful bacteria and no antibacterial peptide was set as the control, and then placed in a microbial growth analyzer (microplate reader) for growth curve determination. They were cultured at 37°C for 12 - 16h, and the absorbance was measured at a wavelength of 600nm.

[0044] Table 1: Inhibition rate table of synthesized small peptides against harmful bacteria

[0045]

[0046] The results in Table 1 show that both small peptides have obvious antibacterial effects; compared with the antibacterial effect of the small peptide produced by Lactobacillus plantarum from duck before domestication, the antibacterial effect of the small peptide produced by Lactobacillus plantarum from duck with high selenium ion loading after domestication is better.

[0047] Example 4: Comparison of the antibacterial effects of postbiotics of Lactobacillus plantarum from duck before and after domestication

[0048] The growth of harmful bacteria in ducks (Escherichia coli, Riemerella anatipestifer, Salmonella) was tested using un-domesticated Lactobacillus plantarum from ducks and the postbiotics of high-selenium-loaded Lactobacillus plantarum from ducks in Example 1. After culturing the two strains of Lactobacillus plantarum in MRS broth for 24 h, the supernatant (metabolites) was taken and mixed with the broth medium containing harmful bacteria in a certain proportion (the ratio of supernatant to harmful bacteria was 1:4 and 1:9). Then, the mixture was placed in a microbial growth analyzer (microplate reader) to measure the growth curve for 36 h.

[0049] Figure 7 , Figure 8 , Figure 9 The results of the antibacterial test showed that when the addition amount of the two strains of postbiotics was 1:4 compared to the harmful bacteria, both postbiotics had a significant antibacterial effect, and the harmful bacteria remained in a non-growing state for 15 consecutive hours. This indicates that the postbiotics of Lactobacillus plantarum from ducks have an obvious inhibitory effect on Escherichia coli, Riemerella anatipestifer, and Salmonella, and the inhibitory effect of the high-selenium-loaded Lactobacillus plantarum from ducks is better. When the addition amount of the two strains of postbiotics was 1:9 compared to the harmful bacteria, both the postbiotics of Lactobacillus plantarum from ducks and the high-selenium-loaded Lactobacillus plantarum from ducks could delay the time for Riemerella anatipestifer to enter the exponential growth phase and significantly inhibit the growth activity of Riemerella anatipestifer; the postbiotics of the high-selenium-loaded Lactobacillus plantarum from ducks could delay the time for Salmonella to enter the exponential growth phase and had a certain antibacterial effect; the inhibitory effect of the postbiotics of Lactobacillus plantarum from ducks and the high-selenium-loaded Lactobacillus plantarum from ducks on Escherichia coli was not obvious at the addition amount of 1:9.

[0050] Figure 10 , Figure 11 , Figure 12 The results of the flow cytometry and Table 2 showed that when the addition amount of the two strains of postbiotics was 1:4 compared to the harmful bacteria, the apoptosis rate of the harmful bacteria increased significantly, indicating that the postbiotics of Lactobacillus plantarum from ducks have an obvious inhibitory effect on Escherichia coli, Riemerella anatipestifer, and Salmonella, and the antibacterial effect of the postbiotics of the high-selenium-ion-loaded Lactobacillus plantarum from ducks is better than that of the postbiotics of the ordinary Lactobacillus plantarum from ducks.

[0051] Table 2: Table of the effect of the postbiotics of the high-selenium-ion-loaded Lactobacillus plantarum from ducks on the apoptosis rate of harmful bacteria

[0052]

[0053] By Figure 13 , 14It can be seen that SEM images at the same magnification show that the cells of Escherichia coli and Riemerella anatipestifer are intact; when the supernatant of Lactobacillus plantarum from duck sources with high selenium ion load (postbiotics) is added at a ratio of 1:4 to the harmful bacteria and the two harmful bacteria are cultured for the same period of time, both Escherichia coli and Riemerella anatipestifer show phenomena such as shrinkage, rupture, and distortion, indicating that the postbiotics of Lactobacillus plantarum with high selenium ion load can not only inhibit the growth of Escherichia coli and Riemerella anatipestifer, but also cause cell rupture.

[0054] Example 5: Effect of Postbiotics of Lactobacillus plantarum from Duck Sources with High Selenium Ion Load (Se 4+ ) on the Growth and Development of Meat Ducks

[0055] In this experiment, 120 one-day-old male Pekin ducks were selected and randomly divided into 5 groups, with 4 replicates in each group and 6 ducks in each replicate. This experiment used 4 treatment groups and 1 control group. The bacterial concentration in the probiotic preparation was 1×10 9 CFU / mL, and 4L of the bacterial solution was added to each ton of the basal diet. CON group (control group): fed the basal diet (the composition of the basal diet is shown in Table 3); Group I: added conventional unfortified Lactobacillus plantarum from duck sources to the basal diet; Group II: added the fermentation broth of Lactobacillus plantarum from duck sources with high selenium load in Example 1 to the basal diet; Group III: added the postbiotics of Lactobacillus plantarum from duck sources with high selenium load to the basal diet; Group IV: added the cells of Lactobacillus plantarum from duck sources with high selenium load to the basal diet. The experimental feeding period was 42 days, and after 42 days, slaughter sampling was carried out. The feeding experiments in Examples 4, 5, 6, 7, and 8 were the same.

[0056] Table 3: Composition of the Basal Diet for Meat Ducks %

[0057]

[0058]

[0059] 1 The vitamin premix and trace element premix provided VA 12,000 IU, VD 3 2,500 IU, VE 20 mg, VK 3 3 mg, VB 1 3 mg, VB 2 8 mg, VB 6 7 mg, VB 12 0.3 mg, D-pantothenic acid 20 mg, niacin 50 mg, folic acid 1.5 mg, biotin 0.1 mg, copper (as copper sulfate) 9 mg, zinc (as zinc sulfate) 110 mg, iron (as ferrous sulfate) 100 mg, iron (as ferric sulfate) 100 mg, iodine (as potassium iodide) 0.6 mg.

[0060] 2 The metabolizable energy is a calculated value, and the others are measured values.

[0061] Table 4: Growth performance of meat ducks at 42 days of age

[0062]

[0063]

[0064] Note: Different lowercase letters in the superscripts of the data in the same row indicate significant differences (P < 0.05), and the same or no letters indicate no significant differences (P > 0.05). The same applies to the following tables.

[0065] As can be seen from Table 4, there were no significant differences in ADG, ADFI, and F / G among the experimental groups from 1 to 21 days compared with the CON group (P < 0.05). From 22 to 42 days, the average daily gain of Group II and Group III was significantly higher than that of the CON group (P < 0.05), and the feed-to-gain ratio was significantly lower (P < 0.05). From 1 to 42 days, the average daily gain of Group II and Group III was significantly higher than that of the CON group (P < 0.05), and the feed-to-gain ratios of Group II, Group III, and Group IV were significantly lower than that of the CON group (P < 0.05). The results of Group II and Group III were better than those of Group IV with the addition of pure cells of Lactobacillus plantarum with high selenium load alone in the diet, indicating that the digestive enzymes in postbiotics played an intervention role in the growth performance of meat ducks, suggesting that the domesticated postbiotics of Lactobacillus plantarum from duck origin with high selenium load could improve the feed conversion rate of meat ducks.

[0066] Example 6: Effect of postbiotics of Lactobacillus plantarum from duck origin with high selenium load (Se 4+ ) on the slaughter performance of meat ducks

[0067] Table 5: Slaughter performance of meat ducks at 42 days of age

[0068]

[0069]

[0070] As can be seen from Table 5, the semi-eviscerated rates of Group II, Group III, and Group IV were significantly higher than that of the CON group (P < 0.05), and the slaughter rate of Group II was significantly higher than that of the CON group (P < 0.05). The eviscerated rates, breast muscle rates, and leg muscle rates of all experimental groups had an increasing trend (P > 0.05). It shows that the domesticated postbiotics of Lactobacillus plantarum from duck origin with selenium load (Se 4+ ) have the effect of improving the slaughter performance of meat ducks.

[0071] Example 7: Effect of postbiotics of Lactobacillus plantarum from duck origin with high selenium load (Se 4+ ) on the meat quality of meat ducks

[0072] Table 6: Table of meat quality indicators of 42-day-old meat ducks

[0073]

[0074] As can be seen from Table 6, compared with the CON group, the pH of Group II increased significantly (P < 0.05), and the a* value of redness in Group III increased significantly (P < 0.05). The cooking loss of Group IV decreased significantly (P < 0.05). There were no significant differences in the L* value of brightness, b* value of yellowness, drip loss, and shear force among the experimental groups (P > 0.05). It shows that adding domesticated selenium ion-loaded (Se 4+ ) postbiotics of Lactobacillus plantarum from duck source can increase the pH of the breast muscle of meat ducks, improve the redness of meat color, enhance the color of duck meat, and improve the water-holding capacity of meat.

[0075] Example 8: Effects of high selenium ion-loaded (Se 4+ ) postbiotics of Lactobacillus plantarum from duck source on antioxidant indexes of meat ducks

[0076] Table 7: Table of antioxidant indexes of 42-day-old meat ducks

[0077]

[0078] In animals, selenium mainly circulates and functions in the form of selenoprotein, catalyzing glutathione into oxidized glutathione, and is an effective antioxidant element in animals. The antioxidant system plays an important role in maintaining the health of the body. As an important part of the antioxidant system, the activity of antioxidant enzymes can reflect the antioxidant capacity of the body. As can be seen from Table 7, compared with the CON group, Group II could significantly increase the activity of serum total superoxide dismutase (P < 0.05) and reduce the content of malondialdehyde. The activity of total superoxide dismutase in Group I also increased. The activity of glutathione peroxidase in Group III was significantly higher than that of the control group (P < 0.05), and the activity in Group II also increased. It shows that high selenium ion-loaded (Se 4+ ) postbiotics of Lactobacillus plantarum can increase the activity of total superoxide dismutase, scavenge peroxidation free radicals, and improve the antioxidant capacity of the body.

[0079] Example 9: Effects of high selenium ion-loaded (Se 4+ ) postbiotics of Lactobacillus plantarum from duck source on intestinal immune indexes of meat ducks

[0080] Table 8: Table of intestinal immune indexes of 42-day-old meat ducks (μg / ml)

[0081]

[0082] As a system that directly contacts the external environment of the animal body, the intestine is in long-term contact with various pathogenic microorganisms and naturally becomes the first line of defense against the invasion of pathogenic microorganisms through the digestive tract. The intestinal mucosal immune system is the material basis of this barrier. As shown in Table 8, compared with the CON group, the contents of IgA and IgG in the jejunum mucosa of the experimental group of meat ducks increased significantly (P < 0.05), and the content of IgM showed an increasing trend (P > 0.05), indicating that the postbiotics of Lactobacillus plantarum with high selenium ion (Se 4+ ) have a positive effect on improving intestinal mucosal immunity.

[0083] Example 10: Effects of postbiotics of duck-derived Lactobacillus plantarum with high selenium ion (Se 4+ ) on the fatty acids in the pectoral muscle of meat ducks

[0084] Table 9: Composition table of fatty acids in the pectoral muscle of 42-day-old meat ducks

[0085]

[0086]

[0087] The proportion of fatty acid content is an important indicator for evaluating the nutritional value of meat quality. As shown in Table 9 and Figure 15 , compared with the CON group, the content of C18:0 in group III decreased significantly (P < 0.05), and the contents of C18:1n9c and C18:3n6 increased extremely significantly (P < 0.01), resulting in an extremely significant increase in the content of MUFA (P < 0.01), thereby optimizing the fatty acid structure. The content of C20:3n6 in group I also increased (P < 0.05), and there was no significant difference in the fatty acid composition of the other groups compared with the CON group (P > 0.05). It shows that the postbiotics of Lactobacillus plantarum with high selenium ion (Se 4+ ) also have a positive effect on improving the fatty acid composition of meat ducks.

[0088] In summary, the high-selenium duck-derived Lactobacillus plantarum domestically selected and obtained by the method of gradually increasing the concentration of selenium ion (Se 4+ ) in the culture medium adopted in the present invention not only has the probiotic advantages of duck-derived Lactobacillus plantarum, but also has the ability to carry high selenium ions, can improve the intestinal selenium absorption rate, and reduce the pollution of selenium ion (Se 4+ ) to the environment. At the same time, the postbiotics produced by the domestically selected and bred high-selenium duck-derived Lactobacillus plantarum are rich, containing small peptides (antibacterial peptides), small molecule organic acids, digestive enzymes, etc. Because it is rich in targeted antibacterial peptides, it has obvious inhibitory effects on harmful bacteria such as Escherichia coli, Salmonella, and Riemerella anatipestifer. Other bioactive substances such as digestive enzymes contained can promote the growth and development of poultry and improve the product quality.

Claims

1. A small peptide with antibacterial effect, characterized in that: The amino acid sequence of the small peptide is SEQ ID NO: 1 or SEQ ID NO:

2.

2. Use of the small peptide according to claim 1 in the preparation of antibacterial products.

3. A feed for poultry breeding, characterized in that: The small peptide according to claim 1 is added to the feed.

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