Bacteria must deal with the ever changing environment they are in, to survive and prevail. One way they cope with environmental insults is to alter their cell shape to a filamentous phenotype. Bacterial filamentation is the process by which cell growth and DNA replication continues in the absence of cell division, resulting in the formation of elongated cells. This change in cell shape is an important biological mechanism which aids in the survival, pathogenesis and antibiotic resistance of bacteria within different environments. In uropathogenic Escherichia coli (UPEC), filamentation aids in prolonged infection of bladder cells whilst evading detection by host macrophages. However, the underlying mechanisms of filamentation and regulators of cell division that enable this unique morphology still remain unknown. To identify these regulators of division, a novel E. coli expression library was created. Importantly, this expression system did not rely on creating conditions that lead to filamentation but instead allowed for the selection of genes that, when expressed, made cells filamentous. Filamentous cells were then isolated using high-throughput flow cytometry. This screen identified several potential division regulators, including ymfM, an SOS (stress response) inducible gene of the e14 prophage. Initial characterisation of this gene showed that inhibition of division is independent of SulA, a well-known inhibitor of cell division during the SOS response, suggesting activation of an alternative pathway during stress. Furthermore, immunofluorescence microscopy of cells induced to express ymfM revealed that inhibition of division occurs at the level of FtsZ ring assembly (early stages of division). Further work is being done to determine the function of YmfM in inhibiting division, as well as its significance in a pathogenic setting. This will not only enable us to better understand the molecular mechanism of filamentation but provide an opportunity to harness these mechanisms toward better control of bacterial infections.