Lactobacillus casei and application thereof to produce L-lactic acid by fermentation

A technology of Lactobacillus casei and lactic acid, applied in the direction of fermentation, bacteria, and microorganism-based methods, can solve the problems of low optical purity and low conversion rate of fermentation products, and achieve high sugar-acid conversion rate, great social significance and economic value effect

Inactive Publication Date: 2013-06-12
NANJING TECH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Rhizopus belongs to heterolactic acid fermentation with simple nutritional requirements, but the conversion rate is relatively low, and the optical purity of the fermentation product is not high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] This example illustrates the method of performing low-energy nitrogen ion implantation mutagenesis screening on Lactobacillus casei.

[0041] The specific steps for the first step of low-energy nitrogen ion implantation mutagenesis screening are as follows:

[0042] (a), preparation of single spore suspension: get Lactobacillus casei ( Lactobacillus casei ) Add 10 mL of sterile water to the fresh slant of LC-5, scrape and wash the spores, pour them into a 250 mL Erlenmeyer flask with a certain amount of glass beads and shake them for 20 minutes (250 rpm), break up the spore chains, filter with three layers of degreasing gauze, and use blood cells to filter the filtrate. Count on counting plate, adjust spore concentration 10 6 individual / ml.

[0043] (b) Low-energy nitrogen ion implantation mutagenesis: take 0.1 mL of the spore suspension in step (a) and evenly spread it on a sterile plate, and perform low-energy nitrogen ion implantation on those without overlapping c...

Embodiment 2

[0058] This example illustrates Lactobacillus casei ( Lactobacillus casei ) Genetic stability of LC-N235. The results of the subculture fermentation test are shown in Table 2:

[0059] Table 2 Lactobacillus casei ( Lactobacillus casei ) Genetic stability of LC-N235

[0060] Number of passages L-lactic acid production (g / L) 1 160 2 161 3 157 4 152 5 150

[0061] From the results of the genetic stability experiment, it can be seen that after 5 consecutive passages, the L-lactic acid production of the mutant strain Lactobacillus casei LC-N235 is relatively stable and has good passage stability, which can be used as a production strain for further research and development.

Embodiment 3

[0063] This example illustrates the production of L-lactic acid by fermentation of the mutant strain Lactobacillus casei LC-N235.

[0064] The medium formula described in this embodiment (% is mass percent):

[0065] Plate basic medium: glucose 5%, tryptone 0.5%, yeast extract 1.5%, magnesium sulfate heptahydrate 0.05%, heavy calcium carbonate 3%, agar 1.2%, the rest is water, pH 6.8.

[0066] Slant medium: glucose 0.5%, tryptone 0.5%, yeast extract 1.5%, magnesium sulfate heptahydrate 0.05%, heavy calcium carbonate 0.3%, agar 1.2%, the rest is water, pH 6.8.

[0067] Seed medium: glucose 6.0%, tryptone 1.0%, yeast extract 1.0%, magnesium sulfate heptahydrate 0.05%, heavy calcium carbonate 3.0%, the rest is water, pH 6.8. Among them, 0.05MPa of glucose is divided for 30 minutes, and heavy calcium carbonate is divided for 40 minutes of 0.1MPa.

[0068] Fermentation medium: glucose 12%, tryptone 0.05%, yeast extract 1.5%, magnesium sulfate heptahydrate 0.05%, heavy calcium car...

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Abstract

The invention discloses lactobacillus casei LC-N235 with collection number CCTCC (China Center for Type Culture Collection) No: M2012157. According to the invention, the original strain of lactobacillus casei LC-5 is mutated by low-energy nitrogen ion injection; the strain which resists high glucose, adopts EMP path reinforcement and utilizes lactic acid without decomposition can be screened by a high-glucose plate, a succinic acid plate and a pure-lactic acid plate; through fermentation re-screening, the L-lactic acid high-yield strain is screened and used as the original strain for next mutation; and the steps are repeated until the target strain lactobacillus casei LC-N235 is screened. The strain can effectively utilize the cheap corn flour saccharifying liquid to produce L-lactic acid by fermentation, and the saccharic acid conversion rate is high. In a 5L fermentation tank, the output of L-lactic acid reaches 173g / L, which is improved by 46.6% as compared with that of the L-lactic acid produced by fermenting the original strain; and the lactobacillus casei and the application thereof to produce L-lactic acid by fermentation provided by the invention have tremendous social significance and economic values.

Description

technical field [0001] The invention relates to a strain of Lactobacillus casei and its application in fermenting and producing L-lactic acid, belonging to the technical field of microbial fermentation. Background technique [0002] Lactic acid is an ancient and important organic acid. Lactic acid, lactate and its derivatives are widely used in medicine, medicine, feed, chemical industry and other fields. It is widely used as sour agent, preservative and reducing agent in food industry. Lactic acid, especially L-lactic acid has a strong bactericidal effect and can be directly used as a disinfectant in operating rooms, wards, laboratories and other places. L-lactic acid, L-sodium lactate, glucose, amino acid, etc. are compounded into infusion solution, which can treat acidosis and hyperkalemia. Lactic acid can be added to tobacco to maintain the humidity of tobacco and improve the quality of cigarettes. It can also be used to treat textile fibers, which can make it easy to...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C12N1/20C12P7/56C12R1/245
Inventor 李玉燕黄思思虞龙龚文静钱梦宇陈晓双
Owner NANJING TECH UNIV
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