Preliminary Exploration Of Cell-Free System Of Xanthan Gum Fermentation Mechanism

Xanthan gums has unique physicochemical properties, can be dissolved in cold water and hot water, with high viscosity, high acid-resisting, alkali-resisting, salt resistant properties, high thermal stability, thixotropy, suspension property and so on, are often used as a thickener, emulsifier, suspending agent, stabilizer. It is widely used in the fields of chemical, food, ceramics, medicine, textile, printing and dyeing, paint, oil, metallurgy, papermaking, explosives, fire, pesticides and cosmetics and so on, with broad market prospects, it is the world’s largest production scale and the use of very wide micro biological polysaccharide. But later of traditional fermentation methods when xanthan gum content is 2%, the viscosity was as high as 4000cp. In such a high viscosity, dispersion ability of oxygen and material mixing is greatly reduced, thus appear to lack of oxygen, so the fermentation unable to continue, limited further to improve the yield. In addition, to obtain high quality xanthan gum products, you must first remove the cell. Usually the fermentation broth diluted several times, can by centrifugation or filtration to remove bacteria, this will inevitably lead to alcohol consumption increases, and the rising cost of production. Solution to the problem is to continue the xanthan gum fermentation production in fermentation liquid of no mycelium.The main purpose of this subject is to initially explore the mechanism by using our laboratory screened BT-112 Xanthomonas in cell-free system fermentation xanthan gum, not only to achieve the synthesis of in aseptic conditions, but also to reach the yield and excellent quality. Also with the biosynthesis of alpha arbutin subject, realize the alpha arbutin and xanthan gum cogeneration. The main experiment work as follows:1. Medium used for the production of xanthan gum by Xanthomonas BT-112 are optimized, in order to improve the yield and quality of products; Finally get the suitable medium of Xanthomonas BT-112 to product xanthan gum, its specific components are as follows:50g/L sucrose, citric acid 0.3g/L, peptone 3g/L, CaCO3 6g/L, MgSO4 8g/L, KCl 20g/L, KH₂PO4 0.06g/L. The fermentation temperature is 32℃, the speed is 190r/min. The highest yield under this condition of xanthan gum is 45g/L, reached the leading level.2. The use of ultrasonic crushing bacterium, then use the breakup of liquid to synthetize xanthan gum is feasible, The best conditions of ultrasonic crushing cell:Power 480W, frequency 10:8s, working time 25min, temperature control using an ice bath, under this condition the broken rate can reach more than 85%; and the best proportion of broken liquid and gum medium is 1:3.3. Microfiltration degerming experiment:Bacteria can continue to develop, filtrate is used to do cell-free synthesis of xanthan gum. Best adding amount of filtrate is 20mL, primary culture time required for 48h. And explore the effect of glucose, mannose, sodium pyruvate and acetate, the best result is adding 0.15g of pyruvate to shake flask, and natrium aceticum is the worst.