Lactococcus lactis and application thereof

A technology of Lactococcus lactis and microbial strains, applied to Lactococcus lactis and its application field in aquaculture, can solve the problems of fish breeding and production loss, enhance immunity, anti-virus and anti-parasitic less, etc. The effect of improving immune function, enhancing disease resistance and reducing dosage

Inactive Publication Date: 2021-02-19
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disease is mainly concentrated in spring, summer and autumn, and appears between juvenile fish and adult fish weighing more than 100g. It is highly infectious, and the infe...

Method used

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  • Lactococcus lactis and application thereof
  • Lactococcus lactis and application thereof
  • Lactococcus lactis and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Embodiment 1: Isolation and identification of Lactococcus lactis

[0018] 1. Isolation and purification of strains

[0019] After the intestines of Gifu tilapia were homogenized, they were diluted with sterile saline by a 10-fold dilution method, and 10 -3 ~10 -6 Spread the dilution in the dilution range on the MRS solid plate medium; incubate at a constant temperature of 37°C for 24 hours; pick a typical single colony, and repeatedly streak and separate until a pure strain is obtained; the colony becomes a milky white translucent protrusion with neat and smooth edges. The number is KUST48, such as figure 1 shown;

[0020] 2. 16S rRNA sequence analysis

[0021] The finally screened strains were identified by 16sDNA molecular biology, and the total DNA of the strains were extracted with a bacterial genomic DNA extraction kit (Tiangen Biochemical Technology Co., Ltd., Beijing). 1492R (5′-GGTTACCTTGTTAGGACTT- 3′ ) amplifies its 16sDNA fragment; the reaction program ...

Embodiment 2

[0023] Embodiment 2: Tolerance experiment of Lactococcus lactis

[0024] This experiment aims to evaluate the therapeutic effect of Lactococcus lactis on tilapia infected with Streptococcus agalactiae, and provide basic data for its colonization in the intestinal tract of aquatic animals;

[0025] 1. Strong acid tolerance test

[0026] Pick a single colony of Lactococcus lactis KUST48 in 5mL of MRS culture medium and culture it to the growth stage; take 5mL of the bacteria solution and centrifuge at 8000r / min for 10min, discard the supernatant and keep the precipitate, add MRS culture medium with pH=4.0 to the precipitate, shake Evenly, take this liquid for 0h plate dilution and counting, and the remaining liquid is cultivated in a constant temperature shaker at 150r / min and 37°C for 3h, take the liquid plate for dilution and counting for 3h, set up 3 parallels, and Calculate the survival rate, the results are shown in Table 1;

[0027] 2. Tolerance test of artificial gastro...

Embodiment 3

[0039] Example 3: Evaluation of the therapeutic effect of Lactococcus lactis KUST48 on zebrafish infected by Streptococcus agalactiae

[0040] This experiment aims to evaluate the therapeutic effect of Lactococcus lactis KUST48 on zebrafish infected by Streptococcus agalactiae, and provide basic data for its application in aquatic products.

[0041] 1. Experimental animals and strains

[0042] 90 zebrafish, body length (3.4±0.5) cm, body mass (0.3±0.05) g, were purchased from the flower and bird market of Expo Garden, Kunming City, Yunnan Province, China; zebrafish were raised in the laboratory according to the feeding method of zebrafish In the aquarium, the water tank was filled with tap water with sufficient aeration, the water temperature was (27±1) °C, and the zebrafish special feed was fed once a day; the laboratory was kept for 7 days without abnormal death, and the feeding was stopped 72 hours before the experiment. Empty the contents of the bowel;

[0043] Lactococc...

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Abstract

The invention discloses lactococcus lactis KUST48. The preservation number of the lactococcus lactis KUST48 in China General Microbiological Culture Collection Center is CGMCC NO. 20699. The strain isapplied to treatment of zebra fish infected by streptococcus agalactiae, and experimental results show that the strain can significantly inhibit propagation of streptococcus agalactiae in intestinaltracts of zebra fish and reduce the death rate of zebra fish infected by streptococcus agalactiae. The lactococcus lactis aims to replace antibiotics, overcome a series of defects of excessive use ofantibiotics, drug residue, drug resistance, food safety, environmental pollution and the like, improve the immune function of aquatic animals, enhance the disease resistance of the aquatic animals, reduce the use amount of drugs and promote green and ecological development of the aquaculture industry.

Description

technical field [0001] The invention relates to a strain of Lactococcus lactis and its application in aquaculture, and belongs to the technical field of aquaculture technology and disease prevention and control. Background technique [0002] In recent decades, due to the abuse of antibiotics, the efficacy of antibiotics has declined. It is reported that antibiotics can destroy the balance of normal flora in the intestinal tract of the body, leading to the susceptibility of pathogenic bacteria. At the same time, antibiotics will remain in the body, causing problems such as allergies and ecological pollution. As a substitute for antibiotics, probiotics can avoid the side effects of antibiotics, and at the same time help the host absorb nutrients, improve the living environment, enhance the host's rapid response to diseases, and improve the body's immunity. At present, with the rapid development of my country's aquaculture industry, probiotics are also used for fish immunity, ...

Claims

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Application Information

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IPC IPC(8): C12N1/20A23K10/18A23K50/80A61K35/744A61P37/04A61P31/00C12R1/46
CPCA23K10/18A23K50/80A61K35/744A61P37/04A61P31/00C12R2001/46C12N1/205
Inventor 邓先余杨雪娇周晨煜张棋麟林连兵
Owner KUNMING UNIV OF SCI & TECH
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