1. Departamento de Biologia, Pontificia Universidad Javeriana, POB 56710, SantaFe de Bogota, Colombia
2. Laboratoire ORSTOM de Microbiologic des Anaérobies, Université de Provence, CESB-ESIL Case 925, 163 Avenue de Luminy, 13288 Marseille Cedex 9, France
3. School of Biomolecular and Biomedical Sciences, Faculty of Science, Griffith University, Brisbane, Queensland 4111, Australia