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Lactobacillus casei and breeding method thereof

A technology of Lactobacillus casei and bacterial strains, which is applied in the field of Lactobacillus casei and its breeding, can solve the problems of reducing production efficiency, lack, and reducing ATP synthesis ability, etc., and achieve the effect of simple operation and good growth performance

Inactive Publication Date: 2011-06-01
JIANGNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

As the fermentation continues, the accumulation of organic acids continues to increase. During this process, the lactic acid and acetic acid produced by fermentation passively diffuse into the cytoplasm, where they are quickly dissociated into protons and charged acid ions that cannot be leaked out of the cell membrane, and lead to The sharp drop of intracellular pH and the lack of ATP synthesis ability seriously affect the biomass and physiological activity of cells, limit the normal growth and metabolism of cells, and greatly reduce production efficiency

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Example 1 Breeding method of Lactobacillus casei (CCTCC NO: M 2010292)

[0013] With commercial Lactobacillus casei ( Lactobacillus casei ) ATCC334 is the starting strain, it is cultivated in the seed medium to the logarithmic growth phase, inoculated in the fermentation medium of pH5.3 and cultivated to OD 600 =3.0, according to the dilution rate of 0.1 h -1 Feed the fermentation medium to the chemostat at a constant flow acceleration rate to a steady state, then reduce the pH of the culture system to 5.0, and stop feeding (D=0). At this time, the cells grow in the medium with pH5.0, when the cell concentration reaches OD 600 =3.0, add fresh fermentation medium until the steady state is reached. Such repeated operations gradually lowered the fermentation pH to 4.3, and the growth reached equilibrium.

[0014] Take the final culture solution of chemostat culture, spread it on a plate with a pH of 4.3 after appropriate dilution, select a single colony, ferment the s...

Embodiment 2

[0016] The growth characteristics of embodiment 2 Lactobacillus casei Lb-2 acid stress conditions

[0017] 1. Activation of strains

[0018] Will save at -70 o The starting strain Lactobacillus casei ( Lactobacillus casei ) ATCC 334 and the selected Lactobacillus casei Lb-2 were inserted into the seed medium with an inoculum of 2%, at 37 o C cultured statically for 16 hours.

[0019] 2. Seed cultivation

[0020] Take the activated Lactobacillus casei ATCC 334 and Lactobacillus casei Lb-2 respectively to the seed medium with an inoculum of 2%, 37 oC , and cultured statically until reaching the mid-logarithmic phase.

[0021] 3. Fermentation tank culture

[0022] With 2% inoculum, the cultivated seed culture solution was transferred to the fermentation medium respectively, and the pH of the fermentation tank was controlled to be 4.3, with lactic acid and hydrochloric acid as pH regulators, at 37 o C. Culture at 100 rpm for 64 h. After the fermentation, the bacteria in ...

Embodiment 3

[0027] Example 3 Environmental Tolerance Experiment

[0028] 1. Activation of strains

[0029] Will save at -70 o The starting strain Lactobacillus casei ( Lactobacillus casei ) ATCC 334 and the Lactobacillus casei Lb-2 obtained by the selection were inserted into the seed medium with an inoculum of 2%, at 37 o C cultured statically for 16 hours.

[0030] 2. Seed cultivation

[0031] Take the activated Lactobacillus casei ATCC 334 and Lactobacillus casei Lb-2 respectively to the seed medium with an inoculum of 2%, 37 oC , static culture to mid-logarithmic phase.

[0032] 3. Stress experiment

[0033] Cells in the mid-logarithmic growth phase were collected by centrifugation at 4°C and 8000 rpm for 5 min to collect the cells. After washing and centrifuging twice with phosphate buffer (pH 7.0), the cells were resuspended in lactic acid at pH 4.3 and pH 2.5 respectively. After stressing in hydrochloric acid and 1.6% bile salt for 3 h, the cells were centrifuged and wash...

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Abstract

The invention discloses a lactobacillus casei and a breeding method thereof, belonging to the field of a food biotechnology. The method in the invention comprises the following steps: carrying out chemostatic culture on the lactobacillus casei ATCC334 until the lactobacillus casei is in a stable state, reducing the pH value of a culture system, adding a culture medium to be in the stable state according to a certain dilution ratio, reducing the pH value of the system again, and adding the culture medium to be in the stable state according to a certain dilution ratio; and repeating the process until a low pH value-resistant lactobacillus casei (CCTCC NO: M2010292) is screened. The biomass liveweight of the bred bacterial strain in a culture medium with the pH value of 4.3 is improved by 50% compared with that of the original bacterial strain, and the tolerances to lactic acid with the pH value of 3.3, hydrochloric acid with the pH value of 2.5 and 1.6% cholate are respectively improved by 103 times, 4.8 times and 2.3 times. By applying the method in the invention, the tolerance of the lactobacillus casei to environmental stress is effectively improved, and the method in the invention can be used for breeding lactobacillus with environmental stress resistance in the food industry.

Description

technical field [0001] The invention relates to a strain of Lactobacillus casei and a breeding method thereof, belonging to the field of food biotechnology. Background technique [0002] Lactobacillus casei is a kind of probiotics widely used. As an industrialized cell factory, Lactobacillus casei has become the main force of production in the fields of food and fermentation, and has extremely high economic value. However, in the actual industrial production process, Lactobacillus casei inevitably faces the influence of various unfavorable conditions from the external environment. As the fermentation continues, the accumulation of organic acids continues to increase. During this process, the lactic acid and acetic acid produced by fermentation passively diffuse into the cytoplasm, where they are quickly dissociated into protons and charged acid ions that cannot be leaked out of the cell membrane, and lead to The sharp drop of intracellular pH and the lack of ATP synthesis a...

Claims

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Application Information

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IPC IPC(8): C12N1/20C12R1/245
Inventor 陈坚吴重德张娟堵国成
Owner JIANGNAN UNIV
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