Life in changing environments: The intriguing cycles of Polyphosphate Accumulating Organisms

Cells are complex systems continuously exposed to changing, dynamic environments. Understanding howcells respond and adapt is of great interest not only froma fundamental viewpoint but also for the development of solutions for current challenges in medical, industrial and environmental research fields. In this thesis, the bacterial community member Candidatus Accumulibacter phosphatis (hereafter referred to as Accumulibacter) from the functional group of Polyphosphate Accumulating Organisms (PAOs) was selected as study object due to their key-role in phosphorus removal at wastewater treatment processes and their adaptive metabolic strategies to thrive in fluctuating environments. These microorganisms are enriched in Enhanced Biological Phosphorus removal (EBPR) systems where they experience cyclic absence and presence of external electron acceptors (here, anaerobic and aerobic conditions, respectively). These fluctuations together with non-continuous availability of nutrients lead to intricate metabolic strategies. While the overall metabolic traits of these bacteria are well described, the non-availability of isolates has led to controversial hypotheses on which metabolic pathways are used - structure, when are these pathways active