Lipid signatures of acidophilic microbial communities in an extreme acidic environment - Río Tinto, Spain

► We examined the microbial community composition of an acidic river system. ► Analysis of intact polar lipids and fatty acids revealed a dominance of eukaryotes. ► Isolates of predominant bacteria helped identify their lipid footprints. ► Labelling experiment showed the overwhelming importance of phototrophic carbon fixation.