1. 1 Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, Kerklaan 30, 9751 NN, Haren (Gn), The Netherlands. 2 INRA, Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy en Josas Cedex, France. 3 Universidade Federal de Ouro Preto, Laboratoire de Bioquimica e Fisiologia de Microorganismos, ICEBII Campus do Morro do Cruzeiro 35 500.000, Ouro Preto‐Minas Gerais, Brazil.