Fruit is a source of highly fermentable dietary fibre and from this perspective can make a direct contribution to gastrointestinal health. It is known that modifications to the diet can lead to beneficial shifts in the microbiota, both in terms of profile and activity1. However, the relationships between the gut microbial population and specific fibres are poorly understood. Research which will link identity and community dynamics with the metabolic function of microbes from hosts with and without dietary fruit is imperative to understanding this symbiotic environment, with the production of short chain fatty acids essential for nutritional health of the host. A controlled in vivo study, using pigs as a human model, was undertaken to examine the effect of fibre substrates on the community profile of bacteria within specific gastrointestinal tract (GIT) sites. Samples from different GIT sites from animals fed a control and a test diet containing fruit in the form of dried mango powder (15%) were collected for analysis. The two diets were fed for four weeks, and 454 amplicon pyrosequencing of bacterial 16S ribosomal RNA genes was conducted on digesta from five GIT sites. Results comparing digesta from both diets will be presented from stomach, small and large intestinal sites. Preliminary results indicate operational taxonomic units can be unique to individual, diet, and site with percentage abundance ratios significantly (p<0.01) shifted at the Phyla and Family level between sites. Further analysis at the genus and species level collated against collected metadata will be presented. This study is novel in its characterisation of the in vivo response of the gut-associated microbial community to a fibre-rich fruit.