Abstract
This project addresses the main gap in our understanding of the ecology of microorganisms and the role that microorganisms play in biogeochemical cycles. We currently have substantial knowledge about microbial mediated processes and their regulation in the natural environment. We also are beginning to detect the general patterns in microbial community structure in a range of ecosystems. However, it has been proven difficult to relate processes and community structure based on the data available, because many of the detected microbes have no or only a distant affiliation with known cultures. Accordingly, their role in biogeochemical processes and interactions with other members of the community remains unknown. Filling this gap in our basic knowledge on structure and function relationships in microbial communities is a field that is strongly in development. Here I propose to address this gap between microbial community structure and the biogeochemical processes in a range of coastal marine sediments. Carbon degradation in sediments covers the most important biogeochemical processes mediated by microbes. Hence, our focus will be on bacteria involved in the degradation of different classes of organic substrates within the complexity of their natural environment. Our methods will be predominantly based on the use of stable isotope (13C) labeled substrates and their incorporation into biomarkers in order to identify active populations. In the present proposal, we will further explore the possibilities of a lipid biomarker technique developed by me and will extend it by using ribosomal RNA as a biomarker with a recently developed probe-capture method. This will enable us to define the active microbial populations at a much higher resolution than possible with lipids.
Netherlands