Mollicutes are a class of simple bacteria characterized by the lack of a bacterial cell wall and their very small genomes (580 kb to 2200 kb). This phylogenetically coherent group contains a broad range of different plant and animal pathogens, making it an ideal model for understanding gene function, gene regulation, and the evolution of virulence factors in other bacterial pathogens. The recent development of improved tools for manipulating mollicute genomes has transformed research in this area, permitting new insights into mollicute molecular and cellular biology. An interesting fact to...