Preparation, Extraction And Application Of Extracellular Polysaccharide From Pseudomonas Sp.PB-3

Extracellular polysaccharide of microorganisms can be permanent as a renewable resources, compared with the plant polysaccharides, as well as natural and synthetic polymers. They not only have many common properties, but it is basic non-toxic. Under the condition of different region or climate, its yield and quality are relatively stable. It is widely used and has a high value. Studies have found that in the pharmaceutical industry, microorganisms extracellular polysaccharide has significant role in many aspects, for example, antitumor, antivirus, resistance to radiation and contravariance, etc. It also has a high potential value in the field of lowering blood sugar and immune. In the food industry, it can be used as a gel, moisturizing agent, thickener and stabilizer etc and plays an important role. In addition, environmental optimization and sewage treatment, have a great space to develop as a microbial flocculant.In activated sludge taken from shore group companies, screened one strain PB-3poducted extracellular polysaccharide PB-3Pseudomonas sp. identified through physiological and biochemical identification and16s rDNA sequence analysis.Through the single factor experiment analysis, multiple parameters are optimized in the Pseudomonas sp. PB-3polysaccharide fermentation process, determined the sucrose as the best carbon source and nitrate as the best carbon source. Then by the response surface method, the fermentation conditions and produced polysaccharide medium of Pseudomonas sp. PB-3were optimized, the best ratio for the medium: sugar43.42g/L,NaNO32.07g/L,K2HPO45.14g/L,KCI0.1g/L, MgSO4-7H2O0.2g/L. In the culture medium, PB-3strains were inoculated for80h. The maximum number of bacterial extracellular polysaccharide is13.70g/L, increasing18.30%over the medium optimization before, we obtain the best culture conditions: temperature30.89℃, the quantity10.44%, cell age19.47h, fluid volume50ml, table speed200RPM, initial fermentation pH7.0, fermentation time80h. Based on the optimized culture conditions, the extracellular polysaccharide maximum of Pseudomonas sp.PB-3fungi is15.57g/L, increased by10.43%than that of before optimization fermentation conditions.By ice ethanol fractional precipitation,we obtain Pseudomonas sp. PB-3fungus polysaccharide products HC-7, then using sevag method for deproteinization, CM-Sepharose Fast Flow ion exchange chromatography, Sephacryl S-500gel filtration chromatography, we get a pure polysaccharide component HC-L. After its physical and chemical properties and its components are measured, we obtain the main ingredient is polysaccharides,.By the measurement, the total HC-L sugar and glucose uronic acid content is92.79%and40.37%respectively. The polysaccharide HC-L from Pseudomonas sp. PB-3fungus is white powder,and it can dissolve in cold water. After it is dissolved in water, it is a thick and transparent solution, and HC-L molecular weight is192KDa. By ultraviolet spectrometry, there are no absorption peak of HC-L nearly260nm and280nm,so we can cnclude that HC-L don’t contain proteins and nucleic acids. By the Infrared spectra of HC-L,we get that the vibration contraction of-OH is in3425cm-1,.All sugars have this property, because the hydrogen bond exists in sugar intramolecular or intermolecular. The-OH stretching vibration between3600cm-1-3200cm-l is a broad peak.The stretching vibration of C-H appears in2920cm-1.While stretching vibration of C=O in carboxyl appears in the1616cm-1and1724cm-1,and the C-O stretching vibration in a variety of hydroxyl finds in the1053cm-1.This article also studied the flocculation of HC-7and had a detailed optimization analysis towards factors affecting the flocculation.Through the study of carbon and nitrogen source, we obtain cane sugar and organic nitrogen source have better effect for flocculation. Through the research on culture medium initial pH, aeration, reaction pH, added amount of flocculant, ion species and temperature, we know that the HC-7have high flocculating activity, high heat resisting property, alkali resistance, insolution, etc. Flocculation of dipdye wastewater and the water from the Yellow River are measured separately. They all achieved good effect with flocculating rate of93.72%and94.67%respectively.