This invention relates to a method for decreasing the foam formation during cultivation of a microorganism and to a method for producing an enhanced amount of a product of interest. The method comprises that the microorganism is modified in such a way that the microorganism does not produce an essential amount of at least one of the proteins, polypeptides or peptides associated with foam formation during cultivation of the unmodified microorganism. In particular the method comprises that the microorganism is modified not to produce an essential amount of amphipathic or hydrophobic proteins, polypeptides or peptides.