The gut microbiota plays a critical role in human health by fermenting dietary fiber into beneficial metabolites such as short-chain fatty acids (SCFAs). However, interactions between gut microbes and fiber are complex and poorly understood, which hinders the development of targeted microbiome-based therapies. This project aims to bridge this gap by investigating the genetic, spatial, and temporal organisation of fiber degradation in the gut. To achieve this, we will employ imaging techniques to map the functional organisation of the gut microbiota in relation to defined fiber particles and conduct in vivo and in vitro experiments to establish causal relationships between genes and fiber degradation. Our research is structured into three interconnected work packages: (1) Characterising in vivo fiber degradation by mapping the in situ spatial relationships between key gut microbes and dietary fibers and identifying gene functions related to fiber binding and degradation; (2) Investigating the spatio-temporal dynamics of fiber degradation, (3) Studying the ecology of fiber degradation, exploring how interspecies interactions, such as syntrophy and competition, influence the spatial organisation and efficiency of fiber degradation. Ultimately, this will provide a foundation for the targeted manipulation of gut microbial communities to improve health outcomes.