Isolation of endophytic bacteria from cotton and screening of antagonistic bacteria

252 bacteria strains were isolated from different internal tissues of cotton cultivars collected from Xinjiang regions. These strains were preliminarily classified as Bacillus sp., Xanthomonas sp., Pseudomonas sp., Erwinia sp., and Curtobacterium sp. Among these five genera,Bacillus sp. was the most prevalent endophytic bacterium in cotton. Results indicated that population densities of endophytic bacteria ranged from 1.0×10 to 1.4×10~8 cfu/g fresh weight although it might vary depending on cultivar ,tissue and region of the plant. Population of the endophytic bacteria is the largest in seed, small in root,smaller in stem, leaf and bud, the smallest in petiole. Of the 87 isolates, 22 strains are known to express antibiosis activities against Fusarium oxysporium f.sp., and 15 strains are known to express antibiosis activities against Rhizoconia solani kuhn, 15 strains were determined in vitro antagonism to both of the pathogens.This study indicaes that selected endophytic bacteria trains have potential for biological control of cotton disease.