1. UNESCO MIRCEN: Industrial Biotechnology, Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, P.O. Box 339, Bloemfontein 9301, South Africa.
2. Centre for Confocal & Electron Microscopy, University of the Free State, P.O. Box 339, Bloemfontein 9301, South Africa.