.................................................................................................................................... iii OPSOMMING ................................................................................................................................ iv ACKNOWLEDGEMENTS ................................................................................................................... v TABLE OF CONTENTS ..................................................................................................................... vi LIST OF FIGURES ............................................................................................................................ xi LIST OF TABLES ............................................................................................................................. xvi LIST OF ABBREVIATIONS .............................................................................................................. xvii General Introduction ................................................................................................... 1 Background ...................................................................................................................................... 1 Brief review of objectives and methodological approach ............................................................... 3 Dissertation layout .......................................................................................................................... 3 Literature Review ........................................................................................................ 5 The human microbiota and microbiome ......................................................................................... 5 The core Microbiota / Microbiome ................................................................................................. 6 Contribution of the core towards health ........................................................................................ 7 Metabolic Functions ................................................................................................................. 8 Mucosal epithelium effect and defence barrier ....................................................................... 9 Host immune modulation ........................................................................................................ 9 Dysbiosis ........................................................................................................................................ 10 Effect of microbial metabolites on health .............................................................................. 10 Dysbiosis and GI tract disorders ............................................................................................. 11 Dysbiosis and systemic diseases ............................................................................................. 12 The gut-brain-axis: Dysbiosis and central nervous system disorders .................................... 13 Manipulating the gut microbiota to maintain health and treat disease ....................................... 14 Probiotics ................................................................................................................................ 14 Stellenbosch University https://scholar.sun.ac.za