FnrL and three Dnr regulators are used for the metabolic adaptation to low oxygen tension in Dinoroseobacter shibae

The adaptation strategies and regulatory networks behind the adaptation of D. shibae DFL12T to changing oxygen regimes was investigated. Moreover, the essential role of 4 Crp/ Fnr like regulators within this adaptation process was revealed using transcriptional analysis of regulator knock out strains. Dinoroseobacter shibae DFL12T (DSM 16493T) and generated Crp/ Fnr regulator depletion strains (DS001 (DfnrL), DS002 (DdnrD), DS003 (DdnrE) and DS004 (DdnrF)) were grown in artificial saltwater minimal medium (SWM) supplemented with 16.9 mM succinate in baffled flasks shaking at 200 rpm for aerobic growth and for anaerobic cultivation 25 mM nitrate was added and incubation was performed in serum flasks with rubber stoppers shaking a 100 rpm. D. shibae wild type and mutant strains were grown under aerobic conditions up to the mid exponential growth phase (OD578 nM 0.5) and shifted to anaerobiosis to mimicke the physiologic conditions in the marine habitat. The samples were taken before (as reference) shift and 60 minutes after the shift. Three biological replicas were analyzed. Comparison: Identification of genes induced or repressed in the Dinoroseobacter shibae DSM 16493T Crp/ Fnr regulator mutant strains and wild type strain under changing oxygen regimes.