2-keto-L-gulonic acid fermentation process

Abstract

The invention relates to a 2-keto-L-gulonic acid fermentation process. Culture medium containing sorbose, corn steep liquor, urea, magnesium sulfate, monopotassium phosphate and light calcium carbonate nutrient substances is added into a fermentation container, mixed bacteria liquid which can convert the sorbose into 2-keto-L-gulonic acid is added, fermentation is carried out for 2 to 12 hours, lysozyme is added, the dosage of the lysozyme in the fermentation broth is 10U / ml to 10000U / ml, culture is continued, the culture temperature is controlled at 28 DEG C to 35 DEG C in the whole fermentation process, the culture pH value is controlled at 5.4 to 8.5, and fermentation is finished until the residual sorbose in the fermentation broth is lower than 1mg / ml. Through the process, the dosage of the lysozyme is reduced, the fermentation period is shortened by 10 to 15 hours, the production efficiency is increased, and the production cost is reduced.

Description

Technical field: [0001] The invention relates to the field of vitamin C processing, in particular to a 2-keto-L-gulonic acid fermentation process. technical background: [0002] 2-keto-L-gulonic acid is an important precursor for the synthesis of vitamin C. At present, major domestic vitamin C manufacturers all adopt the "two-step fermentation method" production process invented by Yin Guanglin in my country in the 1970s. The key step of this technology is the second-step fermentation process. It is biologically oxidized to 2-KLG under the action of a mixed strain of bacteria. The mixed strain is composed of two kinds of microorganisms, among which the microorganism that converts sugar to acid is originally named Gluconobacter oxidans (commonly known as small bacteria in the industry, Gram Negative bacteria), in recent years, its classification position has been re-determined after systematic identification, and the small bacteria has been renamed as common ketogenic colo...

AI Technical Summary

Problems solved by technology

[0003] In the process of mixed bacteria fermentation, large and small bacteria have both symbiotic and antagonistic effects, and a synergistic symbiotic relationship can be formed during fermentation. However, since two kinds of microorganisms are cultivated together, once the ratio of mixed bacteria is out of control, it will cause abnormal fermentation. , the cycle is extended, so it is particularly important to develop a new technology or new process that can regulate the microecology of large and small bacteria, and then shorten the fermentation cycle of gulonic acid. Chinese patent 200810242674.7 discloses a vitamin C precursor that controls the growth of large bacteria The production method of 2-keto-L-gulonic acid is based on the difference in effect of lysozyme on the cell walls of Gram-positive bacteria and Gram-negative bacteria. 12 to 15 hours after the start of fermentation, add lysozyme at a concentration of 100,000 U / ml to 200,000 U / ml to destroy the cell wall of the large bacteria, so that the large bacteria can be rapidly cleaved and released intracellular active substances to promote the growth of small bacteria and acid production, making the mixed bacteria Yield increased, fermentation cycle shortened, because lysozyme is expensive, and the amount of lysozyme used in this method is very large, which largely limits its application in industrialized large-scale production