Cell-to-cell interactions and signalling of marine bacteria with diatoms
In the marine carbon cycle CO2 from the atmosphere and the surface water is fixed by photosynthetic organism such as diatoms which produce dissolved organic matter (DOM) or particulate organic carbon (POC). DOM can be remineralized by heterotrophic organisms and thus be reintroduced into the marine food web in form of new biomass. POC can form aggregates, called marine snow particles, consisting of a variety of organisms. Due to their relatively large size marine snow particles sink down in the water column and burry carbon in the deep ocean.
In this project, the process of aggregate formation by bacteria and diatoms will be studied with the model system consisting of the Gamma-proteobacterium Marinobacter adhaerens HP15 and the diatom Thalassiosira weissflogii. Experimental set-ups to study the aggregation process will include physically separated co-incubations, roller tank experiments and attachment assays. Subsequent proteomic analysis of M. adhaerens HP15 via 2DE-PAGE and protein identification by MALDI-ToF MS will help to identify proteins and the respective genes involved in diatom-bacteria interactions. The role of potentially involved genes will be further studied by generating gene-specific mutants of M. adhaerens HP15 and their phenotypic characterization during the interaction with T. weissflogii.
Figure 1. Interaction of bacteria with diatoms Figure 2. Comparative proteomics using 2D-gels