1. Department of Biological Science, Faculty of Life and Environmental Science, Shimane University, Matsue 690, Japan1;
2. Department of Microbiology and Immunology, University of Leicester, Leicester LE1 9HN, United Kingdom2; and
3. IFR ‘Systèmes Intégrés’, Laboratoire de Microbiologie, Faculte des Sciences et Techniques de Rouen, F76821 Mont Saint Aignan Cedex, France3