The present invention relates to a method for generating a novel form of life comprising the steps consisting of: a) irreversible alteration of the genome of a microbial clone; b) cultivation of a vast population of microbial cells originating from the altered clone obtained in step a) during numerous generations under conditions allowing selection for a higher and stable proliferation rate; c) isolation of descendant clones within the cultivated population of step b) still bearing the alteration of step a).