The study of natural associations between bacterial pathogens or symbionts and their multicellular hosts is often limited by the different scales on which these co-habiting organisms operate. One such example is that of coral diseases, many of which are associated with pathogenic bacteria that colonize the coral tissue, driving the breakdown of the coral-algal symbiosis or the demise of the coral holobiont. To date, a mechanistic understanding of the microscale processes underlying colonization and infection by these pathogens is largely missing. Elucidating these processes is inherently difficult due to the physical and biochemical complexity of the different microenvironments formed around and within the coral colony. In my talk I will present a novel microfluidic-based platform enabling to maintain micro-colonies of the reef building coral Pocillopora damicornis under controlled physico-chemical conditions for periods of hours to days. This approach enables direct microscopic observation of the bacterial pathogen Vibrio coralliilyticus as it penetrates and destroys its coral host. Combined with quantification of bacterial pathogens and enzymatic activity at the system’s exit, these observations allow us to follow the infection process at previously unavailable spatio-temporal resolutions. This enables us to generate and test novel hypotheses regarding bacterial colonization and the onset of disease, as well as the response of the coral host to bacterial attack. This system provides a powerful tool for the study of coral disease, as well as other environmental stresses threatening the future of corals and coral reefs.
