Abstract

Oceanic bacterivory is the process through which marine bacteria are grazed by microbial eukaryotes. It consumes a large fraction of bacterial production, transfers bacterial biomass to upper trophic levels, and completes the inorganic nutrient recycling needed for regenerated primary production. Despite its central role in marine food webs, the identity of the dominant grazers is not well known, and in situ bacterivory rates are seldom measured. Consequently, it is impossible to predict how oceanic bacterivory will react in light of the dramatic anthropogenic change we are facing. In GENEXLAB I propose to use two cultured species from distant eukaryotic lineages shown to be dominant in oceanic systems (Objective 1), and study their gene expression when growing on different bacterial species (Objective 2). With these experiments, I envision to identify genes related to phagocytosis that are expressed in distant taxa and in different situations (Objective 3). In addition, I will construct metatranscriptomes from samples taken in a coastal monitoring station in order to identify the expression of these genes in natural assemblages (Objective 4). We have seen before that some cultured species are widespread in oceanic samples, and therefore these represent excellent models to perform lab experiments and identify the genes expressed during phagocytosis. Our project is part of a seminal process to start building a robust set of functional genes and proteins related to the bacterivory process in non-model marine phagotrophs, which will then be applied to assess this process in natural samples.

Ramon Massana

Staff scientist

I am microbial ecologists with a deep interest in protist ecology and evolution