Timing of processes in diatom bacteria biofilms and strategies of dealing with fluctuating conditions
Communities of photosynthesising and nutrient-cycling microorganisms are of fundamental importance for life on Earth. Among them, diatoms and heterotrophic bacteria have coexisted for millions of years and established various interdependencies and interactions. These interactions range from mutualistic to antagonistic and are chemically mediated by metabolites and signalling molecules. However, the photosynthetic activity of the diatoms influences the oxygen, carbon dioxide and pH concentrations in their environment. Across the diurnal cycle, this creates steep gradients of these parameters that can influence the production, characteristics and the utilisation of these metabolites and signalling molecules. This raises the question of how photosynthesis-related chemical factors influence the timing and coordination of interactions in diatom-bacteria communities.
Biofilms provide an ideal environment for investigating these dynamics. They consist mainly of diatoms and bacteria enclosed in the biofilm matrix of extracellular polymeric substances they produce. This microhabitat facilitates the close proximity of extracellular nutrients and metabolic products, allowing studies in a concentrated environment. Isolating and cultivating biofilm members individually or in combination allows for the exploration of different complexity levels. The primary method for studying interactions within the biofilm will be liquid chromatography-mass spectrometry (LC-MS), enabling detailed identification and analysis of metabolites and their temporal dynamics.
Therefore, this project aims to investigate which metabolites and signalling molecules are present in a benthic diatom-bacteria biofilm, whether they exhibit temporal concentration dynamics linked to photosynthesis-related abiotic factors, and what role the individual partners play over the diurnal cycle.
