Abstract: Strain WZM5, extracellular polysaccharide synthesis-bacteria, was isolated from soil of Ongniod desert, Inner Mongolia. Morphology and phylogenetic analysis based on 16S rDNA gene sequences showed that strain WZM5 belongs to the genus of Massilia, exhibiting the highest sequence similarity with Massilia plicata（98.5%）. The fermentation broth of WZM5 belongs to thixotropic fluid, with high viscosity and excellent pseudoplastic. When the microbial agent of WZM5 was sprinkled on the surface of soil, the ability of soil water conservation and fertilizer conservation increased. The results showed that the ability of water retention in clay, loam and sand increased 49.2%, 83.9% and 42.3%, respectively, compared with the control. After leaching experiment, ammonium nitrogen leaching loss reduced 36.1%, phosphate fertilizer leaching loss reduced 96.5%, and potassic fertilizer leaching loss reduced 36.3% in sand. The results of pot experiment showed that cotton seed germination and seedling unearthed was not affected by WZM5-EPS microbial agent, but the growth of cotton seedling was promoted significantly.

Key words: microbial agent, Massilia, water retention, fertilizer retention