Dubble Lunch seminar

1. How to search for new microbial activities: Biology generally proceeds from experimental observations. For example, when nitrogen removal from wastewater started in the nineteen seventies, engineers were surprised when biologists explained them that to convert ammonia into nitrogen, they should first oxidize it all the way to nitrate.Direct oxidation of ammonia was impossible - because it had never been observed. Faced with the astounding microbial biodiversity that lays in front of us, it does no longer make sense to define the possible and the impossible only by what has been observed. I will illustrate this point with the discoveries of two "new" microbial activities: anaerobic ammonium oxidation and methanotrophy coupled to denitrication. Based on these stories I will argue that thermodynamics and metagenomics are two complementary and essential tools to acquire predictive understanding of complex microbial communites. 2. Uncertainties in Environmental modelling:Not all uncertainties in environmental modelling can be dealt with probabilistically using statistical theory. To do so will lead to bias and overconfidence in model parameters and predictions. Finding alternatives is, however, difficult since epistemic uncertainties are, by definition, poorly characterised. An approach based on setting limits of acceptability prior to making any model runs is suggested as a way ahead and illustrated by examples from different fields.