Actinomycetes produce 70% of all known antibiotics, most of which are produced by members of the genus Streptomyces. Furthermore, streptomycetes produce a plethora of other medically relevant... Show moreActinomycetes produce 70% of all known antibiotics, most of which are produced by members of the genus Streptomyces. Furthermore, streptomycetes produce a plethora of other medically relevant natural products as well as industrial enzymes. Streptomyces is a multicellular mycelial organism, and has a complex life cycle involving sporulation. Cell division in Streptomyces is very different from bacteria with planktonic growth, such as the model organisms E. coli and B. subtilis. Understanding the way cell division is controlled in Streptomyces is not only important for fundamental understanding of cell division in multicellular microorganisms, but may be applied to manipulate its morphology in liquid cultures, for more efficient industrial fermentation. Several novel cell division-related proteins were studied in this research, providing new functional insights into their function during growth and development and their localization in time and space in the Streptomyces mycelium. Cell division proteins do not function alone, but are members of a complex interaction network, which work in a disciplined team. The work described in this PhD thesis shows that streptomycetes have different control systems for cell division, which are complementary to each other to ensure cell division occurs at the right place and at the right time. Show less