Abstract:The biocontrol bacterium strain KD-16J was found to have an inhibitory effect on fruit gray mold in vitro and in vivo.And it was identified as Pichia membranifaciens according to morphological，biochemical and internally transcribed spacer gene sequencing.The strain was found that the higher the applied concentration，the better the inhibitory effect on Botrytis cinerea between 105CFU/mL and 108CFU/mL.The inhibition rate of 1×108CFU/mL biocontrol strain on the growth of B.cinerea hyphae was 85.53 %，and it could completely inhibit the germination of spores.When B.cinerea and the yeast cells were co-cultured，swollen tested hyphae，inner substance leakage were observed with a microscope.In addition，the natural incidence of tomato fruits and the incidence of gray mold in the fruits of injured inoculation with B.cinerea could be significantly inhibited by the strain，and the earlier the strain was sprayed，the better the inhibitory effect on fruit gray mold disease in vivo experiments.When the biocontrol bacterium strain KD-16J was preceded by B.cinerea for 36 h，the incidence of tomato fruit only was 29.12 %.