Characterisation of the response of Sphingopyxis granuli strain TFA to anaerobiosis

Abstract

Sphingopyxis granuli strain TFA is an ¿-Proteobacteria isolated from the Rhine river that is able to degrade the organic solvent tetralin. Until now, the Sphingopyxis genus had always been described as strict aerobic, but we have demonstrated in this work that TFA is able to respire nitrate to nitrite in anaerobic conditions, thus becoming the first facultative anaerobic Sphingopyxis strain reported. Two putative Fnr anaerobic regulatory proteins have been found in TFA, FnrN and FixK, which have shown to be necessary for anaerobic growth, being FnrN more relevant than FixK. Transcriptomic analyses of this bacterium by dRNA-seq and RT qPCR have shown differentially regulated genes in anaerobiosis as compared to aerobiosis, which belong to different functional categories. Similar analyses using a double mutant ¿fnrN¿fixK led to identification of genes directly regulated by the Fnr regulators...