This invention concerns a method for preparing a bacterial supernatant comprising culturing a cell of Pseudomonas environmental strain PF-11; and recovering the supernatant. This invention also concerns a method for reducing the amount of a biofilm on a surface, reducing adhesion of at least one organism to a surface, or reducing microfouling or macrofouling on a surface comprising contacting the surface with a supernatant, supernatant fraction, modified supernatant or modified supernatant fraction of Pseudomonas strain PF-11; or a composition comprising a supernatant, supernatant fraction, modified supernatant or modified supernatant fraction of Pseudomonas strain PF-11, and one or more acceptable carriers. This invention also concerns a method for killing or reducing the growth of a fungus or bacterial cell, or killing or inhibiting the development of an insect or marine copepod, comprising contacting the fungus, bacteria, insect or marine copepod with a supernatant, supernatant fraction, modified supernata
