Screening method of Vc two-step fermentation bacterial strains

Abstract

The invention relates to a screening method of bacterial strains and specially relates to a screening method of Vc two-step fermentation bacterial strains. Transformed bacteria and associated bacteria in Vc two-step fermentation are cultured in seed solution of the Vc two-step fermentation in a mixed mode. Fermentation liquor is centrifuged, and then supernatant liquor is transformed to be bacteria liquor A. In addition, the associated liquor in the Vc two-step fermentation is inoculated in culture medium and cultured for 20-28 hours. After culturing, a sterile filtering membrane filters filtering liquor as fermentation liquor B, the transformed bacteria liquorA and the fermentation liquor B are mixed and then diluted. Diluted liquor is extracted to be coated on a isolation culture medium, and cultured at the temperature of 29-37 DEG C for 4-8 days. Bacteria colony of the transformed bacteria is formed. Sterile sodium bromothymol blue indicating liquor with 0.1% concentration is added to the isolation culture medium where the bacteria colony of the transformed bacteria is formed and still for hours from 0.5 to 2. Transformation efficiency is judged as being high or low according to yellow circle around the bacteria colony, so that transformed bacteria strains with high-efficiency transformation capacity are quickly screened. According to the screening method, the condition that an existence of the associated bacteria has an effect on transformation function is avoided, and besides the function that the associated liquor actives growth of the transformed bacteria and acid production is guaranteed. Color changes of indicator can also accurately indicate the transforming capacity of the transformed bacteria, and screening efficiency is greatly improved.

Description

technical field [0001] The present invention relates to strain screening method, specifically a kind of screening method of Vc two-step fermentation strain Background technique [0002] The industrial production of Vc two-step fermentation, the second step fermentation is the mixed fermentation of two kinds of bacteria to realize the biotransformation from L-sorbose to 2-keto-L-gulonic acid. Two kinds of bacteria include bacteria with acid production ability - common ketogenic cologne (commonly known as acid producing bacteria or small bacteria) and associated bacteria that do not have transformation ability but can promote the growth and acid production of small bacteria (commonly known as large bacteria) . [0003] Strain selection is an important way to improve the efficiency of Vc two-step fermentation. [0004] The traditional method needs to firstly match the small bacteria to be screened with the big bacteria, and then carry out the test tube or shake flask fermenta...

AI Technical Summary

Problems solved by technology

The combination of small bacteria and large bacteria is extremely difficult to control, because it involves the influence of multiple factors such as the number of small bacteria, the number of large bacteria, and the culture conditions, so it is difficult to achieve the best matching ratio between the bacteria to be screened and the large bacteria, resulting in The screening results based on gulonic acid production as an indicator cannot really reflect the acid production ability of the small bacteria

It can be seen that the traditional screening method not only has a large workload, but also has low accuracy of the screening method, resulting in low efficiency of small bacteria screening

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