Macrolides are widely used group of antibiotics which act as protein synthesis inhibitors. Besides the inhibition of protein synthesis they also exhibit secondary effects on bacterial cells. Macrolides are known to induce gene expression including the induction of the ribosomal components and cold shock response. These changes can lead to morphological changes in bacteria including the filamentation. However, it is not yet known if the antibiotic induced cell filamentation also has functional consequences. The main aim of present research project is to elucidate the cause and consequences of cell filamentation induced by the best-known macrolide erythromycin. E. coli will serve as a model bacterium for the study. Preliminary experiments have shown that sub-maximal concentration of erythromycin induces heterogeneous filamentation in E. coli and these filaments acquire unusual asymmetric cell division pattern. The focus of this project will be the understanding the mechanisms behind generation of filamentous cells and their functional differences from the normal ones. For example the susceptibility to immune system will be investigated comparing filamentous and normal cells. In addition, other antibiotics will be used for filamentation and resulting filamentous cells will be compared to ones induced with erythromycin. Several methods will be used such as following the behavior of cell division proteins tagged with fluorescent markers (FtsZ, MinCD etc), pulse labeling of old poles, serum susceptibility of filaments etc. Fluorescence microscopy will be used to measure the effects at the single cell resolution and correlate them with cell length.