Method for screening epsilon-polylysine producing strains

Abstract

The invention belongs to the field of microbial fermentation engineering, and relates to a method for screening epsilon-polylysine producing strains. A Dragendorff reagent is added into the surface of a primary screening medium which does not contain an indicator, and the epsilon-polylysine producing strains are screened by forming a brick-red clustering circle with the periphery of a strain generating a transparent circle. The conventional screening method is improved, and the epsilon-polylysine producing strains can be intuitively and efficiently screened. The process is simple, the screening period is effectively shortened, the screening workload is reduced and the screening efficiency is high.

Description

technical field [0001] The invention belongs to the field of microbial fermentation engineering, and specifically relates to a simple and fast ε- Screening method for polylysine-producing bacteria. Background technique [0002] ε- Polylysine ( ε- Polylysine) is a microbial food preservative with excellent antiseptic performance and great commercial potential among natural preservatives. It is usually polymerized by 25-35 lysine residues. natural metabolites. Compared with traditional food preservatives, it has a broad antibacterial spectrum, and can inhibit most Gram-positive bacteria, Gram-negative bacteria, fungi, etc. under neutral and slightly acidic conditions; it is safe and non-toxic, Not only is it harmless to human health, but also has certain nutritional value after catabolism; in addition, it also has the characteristics of good water solubility and good thermal stability. ε- Polylysine is widely used in food preservatives in Japan and Korea. In October 2003...

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Problems solved by technology

[0003] ε- The screening method of polylysine-producing bacteria is complicated. At present, the method of Nishikawa, a Japanese scholar in 2002, is generally used, that is, a certain concentration of basic dye methylene blue is added to the medium, and the positively charged methylene blue is mixed with the same positively charged one. ε- The electrostatic repulsion between poly-lysine produces a transparent circle visible to the naked eye to screen the target strain, and then ferment it through shake flasks to check whether it shows Dragendorff positive reaction from the fermentation broth

Although this screening method is directional and relatively simple, the addition of methylene blue to the medium is toxic to the target strain and will inhibit its growth, and all strains producing hyaline circles must be verified by re-screening through shake flask fermentation. big, long cycle

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