Abstract: By mean of the chrome azural S（CAS）assay,a high-affinity siderophore- producing bacteria WN-H3 was screened out from 28 bacteria,which were isolated from the ryegrass（Lolium perenne L.）rhizosphere soil. According to morphological,biochemical and physiological characteristics,16S rDNA sequence and phylogenetic analysis,the strain was identified as Pseudomonas vranovensis. The optimal medium components（carbon and nitrogen sources）and growth conditions（temperature,rotation speed and initial pH）for siderphore production by strain WN-H3 were researched by one variable-at-a-time method. The result demonstrated that high siderophore production was yeilded at high siderophore- producing ability of 80.4% under the condition of 10 g/L sucrose,5 g/L yeast extracion,5 g/L NaCl,temperature 28℃,initial pH7.5,180 r/min.

Key words: siderophore-producing bacteria, screening, identification, condition optimun