Weak post-acidification lactobacillus helveticus sh2-5-66 and application thereof

A post-acidification and lactobacillus technology, applied in the field of lactic acid bacteria, can solve the problems of lactic acid bacteria retention, complicated operation, unstable genetic traits, etc., and achieve the effect of excellent fermentation index and good genetic stability

Active Publication Date: 2020-05-29
YANGZHOU UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the domestic modification of lactic acid bacteria is still at the level of artificial

Method used

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  • Weak post-acidification lactobacillus helveticus sh2-5-66 and application thereof
  • Weak post-acidification lactobacillus helveticus sh2-5-66 and application thereof
  • Weak post-acidification lactobacillus helveticus sh2-5-66 and application thereof

Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0059] (1) Preparation of Fermented Milk Crude Enzyme Liquid

[0060] Take 10.0g of fermented milk for the 1st, 5th, 10th, 15th, and 20th day of storage, remove the protein with 1% EDTA solution (pH=12, 4°C), resuspend in TE buffer, add lysozyme, and bathe in 37°C for 1 hour. Centrifuge to remove the supernatant, resuspend with normal saline, and crush the cell suspension with a high-pressure cytometer to extract the crude enzyme solution for the determination of β-galactosidase and H + -ATPase enzyme activity.

[0061] (2) Determination of β-galactosidase activity

[0062] (a) draw ONP (o-nitrophenol) standard curve

[0063] (b) β-galactosidase activity assay

[0064] Take 1mL of the crude enzyme solution, place it in a water bath at 37°C for 10min, add 1mL of ONPG solution (pH 7.0, 20mmol / L), react at 37°C for 10min, and immediately add 3mL of 0.5mol / L Na 2 CO 3 The solution terminated the reaction, and the absorbance was measured at 420 nm. .

[0065] β-galactosidase...

Embodiment 1

[0082] Mutation Breeding, Screening and Identification of Weak Postacidification Strains

[0083] 1. Mutation breeding

[0084] Adopt 20W ultraviolet lamp, irradiate distance 30cm, irradiate 0s, 30s, 60s, 90s, 120s respectively, measure the lethality under the mutagenesis time (table 1). After 50s of irradiation, the lethality rate of the strain is above 80%, so the time of mutagenesis irradiation is set at 50s-60s.

[0085] Table 1 Effect of mutagenesis time on the lethality of L.helveticus SH2-1

[0086]

[0087] 2. Screening

[0088] (1) Establishment of post-acidification screening indicators

[0089] In order to determine the screening index of the enzyme coupled with post-acidification of Lactobacillus helveticus SH2-1 for the screening of late-stage mutagenesis strains, this part of the experiment measured the storage period index of L. helveticus SH2-1 after fermentation, and selected two strains with weak post-acidification The strain L.delbrueckii frs4-1 and S...

Embodiment 2

[0102] (1) Fermentation effect experiment of L.helveticus sh2-5-66

[0103] Ferment SH2-1 (L. helveticus SH2-1) and sh2-5-66 (L. helveticus sh2-5-66) in a single strain, or mix it with commercial starter st447 (S. thermophilus st447) in different proportions Mixed bacteria fermentation, determination of the quality index of fermented milk, the specific experimental method is as follows:

[0104] Single-bacteria fermentation: Inoculate the activated strain into the prepared skim milk medium according to the amount of 3%, place it in a constant temperature incubator at 42°C for cultivation, observe the curdling situation, record the curdling time, and place it in a refrigerator at 4°C storage.

[0105] Mixed bacteria fermentation: mix st447 with Lactobacillus helveticus SH2-1 and sh2-5-66 before and after mutagenesis according to the ratio of 1:1, 1.5:1, and 2:1, and add a total of 6 live bacteria ×10 6 cfu / mL for inoculation and fermentation, placed in a 42°C constant temper...

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Abstract

The invention discloses a weak post-acidification lactobacillus helveticus sh2-5-66 and an application thereof. Human-derived lactobacillus helveticus SH2-1 with excellent probiotic characteristics isused as a starting strain, the weak post-acidification lactobacillus helveticus sh2-5-66 is obtained through ultraviolet mutagenesis according to the relationship between the H<+>-ATPase enzyme and the lactobacillus helveticus SH2-1, and with the H<+>-ATPase enzyme activity as a screening indicator, and a preservation number is CGMCC No.19123. The lactobacillus helveticus sh2-5-66 of the invention is used for fermented milk production, the acidity is reduced by 57 degree T compared with the lactobacillus helveticus SH2-1, fermented milk produced by using the lactobacillus helveticus sh2-5-66alone or with commercial streptococcus thermophiles st447 together has excellent fermentation indexes, and at the same time the lactobacillus helveticus sh2-5-66 has excellent genetic stability.

Description

technical field [0001] The invention belongs to the technical field of lactic acid bacteria, and relates to a weak post-acidification Lactobacillus helveticus sh2-5-66 and its application. Background technique [0002] Fermented milk is a milk product with special flavor and rich nutrition, which is made from milk or milk powder, which is sterilized and then fermented with lactic acid bacteria. It is favored by consumers because of its functions of promoting digestion, alleviating lactose intolerance, regulating the balance of intestinal flora, and lowering cholesterol. After the fermented milk is fermented, it needs to be refrigerated at a temperature of 2-4°C for 12-24 hours, which is called the post-ripening period or post-acidification of fermented milk. The minimum pH of fermented milk acceptable to consumers is generally 4.2. However, in the low temperature environment before transportation and sales, lactic acid bacteria still have certain activity and will continue...

Claims

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Application Information

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IPC IPC(8): C12N1/20A23C9/123A23C19/00A23L13/40A23L13/60C12R1/225C12R1/46
CPCC12N1/20A23C9/123A23C19/00A23L13/65A23L13/45C12R2001/225C12N1/205A23V2400/147
Inventor 关成冉陈萱陶志强王丽赵瑞锋陈大卫张臣臣黄玉军陈霞顾瑞霞
Owner YANGZHOU UNIV
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