study biological properties of pseudomonas fluorescens utpf68, biocontrol agent against phytophthora drechsleri

pseudomonas fluorescens utpf68, well-known biocontrol bacteria was used in this study. the volatile metabolites released from utpf68 in na, nag, pda media, could inhibit the growth of fungi p.drechsleri at the rate of 84.44, 83.55 and 67.33 percent, respectively. the results showed that antibiotics production in pda and cma media prevented the growth of p. drechsleri, 100% and 93%, respectively. the results showed that this strain is able to produce all three antibiotics dapg, mapg and the plt. also, the extracellular extracts of utpf68 reduced the vegetative growth of p.drechsleri in extracts concentration. in addition, the bacterium effectiveness against the pathogen in greenhouse cucumber was studied. the bacterium under the in vitro and in vivo conditions was able to control the pathogen; so that, the application of bacterial concentration at 108 cfu/ml in to the soil, reduced the damage resulted from disease up to 60%. also, the use of this bacterium, in the presence and absence of the pathogen as controls, increased the growth of cucumber. the bacterial colonization experiment showed that the population density of strain utpf68 was increased on cucumber root system to 2.3×109 cfu.