Microbial organisms and their metabolic products affect soil structure by binding loose soil particles into stable aggregates. In particular, extracellular polymeric substances (EPS), produced by soil microorganisms, are known to have positive effect on water retention and aggregate stability. Despite the recognition of the positive effect of EPS on soil structure and decades of research on the industrial potential of EPS (e.g. as bio lubricants, thickener and preservatives), the use of EPS-based products in agriculture as soil improver is still very limited. In addition, our knowledge on EPS composition, structure and function, is far from complete. Gaining understanding of the role of EPS in determining soil structure and aggregate stability and elucidation of the mechanisms that regulate the biosynthesis of EPS in soils, could enable the use of EPS-based solution in agriculture to improve soil structure and prevent soil degradation. The project aims to elucidate the effect of different types of soil amendments (complex as well as more readily biodegradable substrates), and of varying carbon to nitrogen ratio’s on the development of microbial communities in the soil, particularly on EPS producing and degrading microbes.