Isolation and identification of Paenibacillus polymyxa from rhizosphere soil of tobacco plantation in Luoyang

To isolate bacteria strains which possess antagonistic activities against soil-borne pathogenic fungi of tobacco from tobacco rhizosphere soil,dilution plating method and dual culture method were adopted to isolate and screen antagonistic bacteria. The bacteria morphological features were observed, and in addition physiological and biochemical experiments and 16S rDNA sequence analysis were used to identify antagonistic strains. A total of 180 bacterial isolates were obtained from 30 rhizosphere soil samples by separation and purification,in which 49 strains had antagonistic function against soil-borne pathogenic fungi. Strain TS681, TS682 and TS683 were strongly antagonistic towards three kinds of pathogenic fungi,and its antagonistic rate to Pythium aphanidermatum,Phytophthora parasitica and Furasium oxysporum reached above 51.43%,68.75% and 60.00%,respectively. Combined with morphological characteristics, physiological and biochemical characteristics and 16S rDNA sequence analysis, the above three strains were identified as Paenibacillus polymyxa.