In an experiment using the flat-stand method,11 strains of bacteria antagonistic against Verticillium dahliae Kleb(Vd) were isolated from healthy cotton plants growing in cotton fields seriously infected with verticillium wilt.Their verticilliuminhabiting rates ranged from 70% to 87.4%.Cotton Verticillium wilt disease was effectively suppressed by 57% over the control by app lication of a mixture of the antagonistic bacteria along with organic fertilizer.Microbial communities were significantly changed in cotton rhizospheric soils in Treatment VS(app lication of mixed antagonistic strain solution),Treatment VF(organic manure),and Treatment VFS(strain solution plus organic manure),among which Treatment VFS was the highest in disease inhabiting rate,reaching 57%.Significant increase in population of bacteria and actinomyces and decrease in population of pathogen microsclerotia were found in these treatments,as compared with that in the control.Based on the physiological and biochemical determination and the 16S rDNA sequence analysis,HJ-5 and DF-15 strains were identified as Bacillus vallism ortis,while DF-14 strain as Bacillus subtilis.This is the first paper that reports Bacillus vallismortis is antibiotic against Verticillium dahliae.