The tool­box of mo­lecu­lar bio­logy has opened a win­dow to the full di­versity of mar­ine mi­croor­gan­isms. New or­gan­isms and biogeo­chem­ical path­ways await their dis­cov­ery. We have pi­on­eered the ap­plic­a­tion of fluor­es­cence in situ hy­brid­iz­a­tion for the iden­ti­fic­a­tion, loc­al­iz­a­tion and quan­ti­fic­a­tion of mi­cro­bial cells.

Single-cell meth­ods are used along (meta)ge­n­om­ics, tran­scrip­tom­ics and pro­teo­m­ics to pre­dict the bio­chem­ical po­ten­tial of not yet cul­tiv­ated Bac­teria and Ar­chaea. These are placed in phylo­gen­etic trees as can­did­ate taxa. We hy­po­thes­ize their eco­lo­gical niches and test our pre­dic­tions by field-go­ing re­search, study­ing both plank­tonic and benthic eco­sys­tems from coastal wa­ters to the deep sea.