Myxobacteria Sorangium Cellulosum Nust06 Producing Extracellular Polysaccharides In Metabolic Regulation And Its Rheological Properties Of The Study

A novel exopolysaccharide was produced by Myxobacterium Sorangium cellulosum NUST06. Its' culture condition was optimized, and the optimized culture condition contained 30g soluble starch, 1.2g KH2PO4, 0.15g MgSO4, 2.5g NaN03, 0.01g FeSO4 and 1000ml H2O. The culture medium was inoculated with 2% (v/v) of the seed culture cultivated at 28 Cfor 28h and then cultured in a 250mL flask containing 30~50 ml of the media. Fermentations were performed on a rotary shaker (200~220rpm) under the following conditions: temperature, 28 C~-30 C; initial pH, 7.0-7.5. Adding 10mg/IZnCl2 to fermentation culture, apparent viscosity of the broth was enhanced by 16%, the same phenomena was not observed adding ammonium molydine or sodium glutamine instead of ZnCI2. Growth kinetics was tested using 721-spectrophotometer at 440nm using the media without inoculation as the standard. S.cellulosum NUST06 grew rapidly and went in stationary phase after 24h, and exopolysaccharide was harvested when the media was cultivated for 48h. Under the condition that the culture was not degermed, apparent viscosity of the fermentation broth reached 8000 cp, and production of biological gum and EPS were 10.25g/l and 4.97g/l respectively.Rheology of exopolysaccharide was tested using NDJ-1 rotational viscometer, exopolysaccharide thickened solution strongly, and exhibited excellent pseudoplastic behaviours and tolerance to salt, no great decline in apparent viscosity was observed in 20%NaCI or 2%CaCI2 solution. Apparent viscosity vs. pH behavior showed a continuous increase with increasing pH from 3 to 13. When temperature was increased to 80癈, apparent viscosity of 0.1%, 0.125%, 0.15% exopolysaccharide solution remained 50%, 51.4%, 40% respectively. There was no synergistic effect between exopolysaccharide and RAM, but EPS enhanced the tolerance of PAM to salt. CTAB could precipitate EPS from from fermentation broth, Polyethylene glycol octylphenyl ether couldn't increase the viscosity of EPS solution. When 0.08% SDS was added to EPS solution, the viscosity was increased by 3.9 fold. And the EPS exhibit the profile of Hydrophobically Associating water-soluble polymers...