产胞外多糖多功能促生菌的筛选鉴定及促生评价OA北大核心CSTPCD

[Objective]To explore the effect of exopolysaccharides-producing strains in promoting plant growth and improving soil properties in saline soils,which may lay a foundation for the development of microbial bacterial agents applicable to saline soil remediation.[Method]Strains with high-yield exopolysaccharide were isolated from the rhizosphere soil of saline-alkali grassland in Kashi,Xinjiang,and species identification was performed based on 16S rRNA gene sequence comparison and phylogenetic analysis.Moreover,the single factor and response surface method were used to optimize the medium components of the excellent strains to increase the yield of exopolysaccharides,and its effects on plant seedlings cultivated in saline-alkali soil and soil aggregate formation were verified by inoculation test.[Result]A total of 19 exopolysaccharides-producing strains were screened,which were divided into 7 genera,of which Pseudomonas were the dominant.The exopolysaccharides yield was 236-1 544 mg/L,especially Pantoea sp.MQ A0.In addition,MQ A0 was capable of nitrogen fixation,indole-3-acetic acid(IAA)secretion,siderophores production and phosphorus solubilization.The optimal fermentation medium of MQ A0 was 12.5 mL/L glycerol,9.0 g/L peptone,5.5 g/L yeast exact and 5.1 g/L CaCO3.Compared with the initial fermentation process,the exopolysaccharides yield reached 2 436 mg/L,which increased by 57.8%.Pot experiments showed that the inoculation of Zea mays with the fermentation broth of MQ A0 had a significant promoting effect on seedling in saline-alkali soil,including the development of plant height,fresh weight,stem diameter,root number and total root length,which increased by 41.2%,203.0%,42.7%,30.4%,99.7%,respectively.And the formation of soil aggregate was significantly promoted by the EPS(P<0.05).[Conclusion]The high-yield exopolysaccharide strain MQ A0 had various growth-promoting properties,and showed positive effects on plant growth and soil improvement in saline-alkali soil.