WELAN GUM

Preparation

method for extracting WELAN GUM from WELAN GUM fermentation broth involves centrifuging and extracting the fermentation broth to obtain the WELAN GUM. The method includes the following steps: A. Fermentation Broth Pretreatment A1. At pH 6-8, add lysozyme with an activity of 100,000 u/g to the fermentation broth. The concentration of lysozyme in the fermentation broth is 100-200 ppm. After stirring evenly, maintain the reaction for 3-5 hours. A2. Heat the fermentation broth from step A1 to 130℃-140℃, maintain for 5-8 minutes, then lower to 60-70℃. Add acidic protease with an activity of 50,000 u/g. The concentration of acidic protease in the fermentation broth is 200-400 ppm. React at pH 3-4 and a temperature of 50℃-60℃ for 2-4 hours to obtain the pretreated fermentation broth.

B. First Extraction: Mix the pretreated fermentation broth with an ethanol solution containing at least 85% (v/v) at a ratio of 1:0.5-0.6, and stir for 30-40 minutes. Adjust the pH of the mixture to 8.0-9.5 to allow the gel to precipitate as flocculent precipitate.

C. First Centrifugation: Separate the solid and liquid components of the mixture from step B to obtain fibrous gel.

D. Second Extraction: Mix the fibrous gel prepared in step C with an ethanol solution containing at least 85% (v/v) at a ratio of 1:0.3-0.5, and stir for 30-35 minutes. Adjust the pH of the mixture to 6.0-6.5 to allow the gel to precipitate as flocculent precipitate.

E. Second Centrifugation: Separate the solid and liquid components of the mixture prepared in step D to obtain fibrous gel.

F. Three-stage elution: Mix the fibrous gel prepared in step E with an ethanol solution containing at least 85% by volume in a ratio of 1:0.4-0.6, stir for 30-35 minutes, adjust the pH of the mixture to 6.0-6.5, causing the gel to precipitate as flocculent precipitate. Separate the mixture into solid and liquid phases to obtain the fibrous gel.

Description

Welan gum is a microbial product that occupies an important position among extracellular polysaccharides due to its novel properties and potential applications. The biopolymer Welan gum is synthesised by a fermentation process mainly by alkali producing bacteria of the genus Alcaligenes sp. It consists of a tetrasaccharide backbone chain polymer containing L-mannose, L-rhamnose, D-glucose and D-glucuronic acid. It is an anionic polysaccharide and therefore has polyelectrolyte properties due to the presence of d-glucuronic acid in its chemical structure^[1].

Uses

Welan gum has commercial applications in the field of cement systems. It acts as a thickener, suspending agent, binder and emulsifier, stabiliser and viscosity builder. It also has potential applications in oil well drilling as it maintains its stability and viscosity at high temperatures^[1].

References

[1] VARINDER KAUR . Welan gum: Microbial production, characterization, and applications[J]. International Journal of Biological Macromolecules, 2014, 65: Pages 454-461. DOI:10.1016/j.ijbiomac.2014.01.061.