Screening and identification of endophytic antagonistic bacteria strain YGRE24 against watermelon Fusarium Wilt and its characteristics

An endophytic bacterium, YGRE24, isolated from surface sterilized root of watermelon by dilution plate method and flat confrontation method, could inhibit mycelial growth of three physiological races of Fusarium oxysporum f.sp.niveum with inhibition rates of 54.76%, 55.95% and 55.24%, respectively. The antagonistic activity was detected in the fermentation broth of YGRE24 as well. The strain YGRE24 displayed a broad-spectrum antagonistic activity to five pathogens, like Fusarium graminearum and Rhizoctonia solani and so on. Furthermore, the strain had the capacity of phosphate-solubilizing, indole acetic acid-producing and siderophore-producing. The results of pot culture experiments showed that the fresh weight and dry weight of shoot were increased by 44.75% and 30.32% after incubated with strain YGRE24. The lesions caused by watermelon Fusarium wilt were obviously reduced by inoculating the strain. According to morphology,bio-physiological and biochemical characteristics and 16S rDNA sequence, the strain YGRE24 was identified as Bacillus subtilis.