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Method for improving yield of epsilon-polylysine by low pH value stress

A polylysine and yield technology, applied in the field of fermentation engineering, can solve the problem of not using ε-PL and the like, and achieve the effects of reducing extraction cost, simple operation mode and increasing economic benefits

Active Publication Date: 2015-04-08
JIANGNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Although the previous research work successfully increased the production of ε-PL by using the method of pH regulation, it did not use the method of extreme low pH environmental stress to increase the production of ε-PL.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Embodiment 1 Two-stage pH control strategy

[0019] 3.26L of fermentation medium was installed in a 5L fermenter for batch fermentation, 0.24L of seed liquid cultivated for 24 hours was inoculated into the fermentation medium, and the pH value was adjusted to 6.8-7.5 to start fermentation. During the fermentation process, the stirring speed is controlled at 200-800rpm, the ventilation rate is controlled at 0.5-2vvm, and the dissolved oxygen is controlled at about 30%. Maintain at 5.0 until the number of bacteria doubles, and then drop the pH to 4.0 spontaneously, and maintain the pH at the set value by automatically flowing ammonia or NaOH solution until the carbon source is consumed and the fermentation ends. In the end, the ε-PL yield and cell mass were 7.83 and 26.89g / L, respectively, and the ε-PL yield was 6.12g / L / d.

[0020] If the residual glycerol or glucose concentration in the fermentation broth drops to 10g / L, automatically add sterilized pure glycerin or 500...

Embodiment 2

[0021] Example 2 The two-stage pH control strategy of falling first and then rising

[0022] 3.26L of fermentation medium was installed in a 5L fermenter for batch fermentation, 0.24L of seed liquid cultivated for 24 hours was inoculated into the fermentation medium, and the pH was adjusted to 6.8-7.5 to start fermentation. During the fermentation process, the stirring speed is controlled at 200-800rpm, the ventilation rate is controlled at 0.5-2vvm, and the dissolved oxygen is controlled at 30%; The pH is kept stable until 36 hours, then the pH is adjusted up to 3.8, and ammonia water or NaOH solution is automatically added to keep the pH stable until the carbon source is consumed and the fermentation ends. Finally, the yield of ε-PL and the amount of bacteria were 8.59 and 27.21g / L, respectively, and the yield of ε-PL was 6.42g / L / d.

[0023] If the residual glycerol or glucose concentration in the fermentation broth drops to 10g / L, automatically add sterilized pure glycerin...

Embodiment 3

[0025] 3.26L of fermentation medium was installed in a 5L fermenter for batch fermentation, 0.24L of seed liquid cultivated for 24 hours was inoculated into the fermentation medium, and the pH was adjusted to 6.8-7.5 to start fermentation. During the fermentation process, the stirring speed is controlled at 200-800rpm, the ventilation rate is controlled at 0.5-2vvm, and the dissolved oxygen is controlled at 30%. After 20 hours of fermentation, the pH is artificially lowered to 2.5 and maintained for 12 hours, and then the pH is raised to 3.5. And automatically add ammonia water to maintain the pH at the set value until the glucose is consumed and the fermentation ends. Finally, the yield of ε-PL and the amount of bacteria were 10.39 and 30.61g / L, respectively, and the yield of ε-PL was 7.12g / L / d.

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Abstract

The invention discloses a method for improving the yield of epsilon-polylysine by low pH value stress and belongs to the technical field of fermentation engineering. In a fermentation process, an acid pH stress process is introduced, namely the pH is artificially or spontaneously reduced to 2.5-3.0 and is maintained for 12-48 hours; then the pH is improved to 3.5-4.5 and keeps stable until the fermentation is finished. With the adoption of a pH regulating and controlling method, the specific growth rate of epsilon-polylysine producing bacteria and the specific synthesis speed of the epsilon-polylysine can be remarkably improved; a material supplementing-batch fermentation manner is combined so that the yield of the epsilon-polylysine is improved by more than 50% when being compared with that a common two-phase pH regulating and controlling method. According to the method, a low pH stress method is introduced into an epsilon-polylysine fermentation process so that the fermentation level of the epsilon-polylysine is remarkably improved. Furthermore, the method is simple to operate and has remarkable effect so that the implementation of large-scale industrial production is facilitated.

Description

technical field [0001] The invention relates to a method for increasing the yield of ε-polylysine under low pH value stress, and belongs to the technical field of fermentation engineering. Background technique [0002] ε-polylysine (ε-poly-L-lysine, ε-PL) is a kind of L-lysine homopolymer synthesized and secreted by microorganisms, which consists of 25-35 L-lysine residues through α- It is polymerized by dehydration condensation of carboxyl group and ε-amino group. ε-PL has the advantages of good water solubility, high thermal stability, edible, degradable and non-toxic to human and environment. In addition, ε-PL also has a broad antibacterial spectrum, and has a good inhibitory effect on Gram-positive bacteria, Gram-negative bacteria, yeast and mold. Therefore, ε-PL, as an excellent biological food preservative, has been approved for use in the food processing industry by Japan, South Korea, the United States, Europe and other countries and regions. In April 2014, my cou...

Claims

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Application Information

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IPC IPC(8): C12P13/02C12R1/465
Inventor 陈旭升毛忠贵任喜东张建华张宏建唐蕾王珂
Owner JIANGNAN UNIV
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