Biofungicide composition derived from a biologically pure culture of a Chilean bacterial isolate obtained from the skin of grapes, corresponding to Serratia plymuthica CCGG2742, to be used as an environmentally friendly biological control agent against fungal diseases of vegetables, in particular fruits susceptible to the infection of Botrytis cinerea, efficiently preventing the germination of conidia and the proliferation of mycelia of said phytopathogenic fungus, furthermore protecting the plant's leaves and fruits from the infection by the same fungus, and having the potential of being used in the biological control of other phytopathogenic fungus and microorganisms.