Screening,identification of strain ZYRH-19 and characteristics of its product welan gum
In this study,a strain ZYRH-19 producing extracellular polysaccharide was isolated from soil.It was classified and identified from the perspectives of morphology,physiology,biochemistry,and 16S rDNA gene sequence,and the extracellular polysaccharide synthesized by strain ZYRH-19 was analyzed and identified.The results showed that ZYRH-19 was a strain of Sphingomonas sp.,and its homology with Sphingomonas sp.ATCC 31555 was 99.93％.The extracellular polysaccharide synthesized by strain ZYRH-19 was welan gum with weight average molecular weight of 5.3 × 106u.The welan gum solution synthesized by ZYRH-19 had good dilution shear property at room temperature.The viscosity of the product solution could reach 1 444.1 mPa·s at the 6 r/min shear rate,and its gel strength was 22.6 g.It had good temperature resistance at 160 ℃.The results showed that the performance of welan gum synthesized by strain ZYRH-19 is very good,which provides a new strain resource for the industrial production of welan gum.
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