This work has been supported by grants BFU2006-13668 and EUI2008-03631 to R. I. Santamaría from the Ministerio de Educación y Ciencia. We thank Dr. M. Virolle for the gift of the strains S. lividans TK24 and Appk. We also thank M. J. Jiménez Rufo and A. Esteban for their excellent technical work. The IBFG acknowledges the institutional support of the Ramón Areces Foundation during 2011–2012. The authors have no conflict of interest to declare.