Phototrophic growth in H. walsbyi. (A) Protein phylogenetic tree showing the position of the "opsin"-homologs encoded by H. walsbyi, indicated as SquareBopI & II and SquareHop for the proton pumping bacteriorhodopsins and chloride pumping halorhodopsin respectively. Trees were constructed with the neighbor-joining method using 1000 bootstrap replicates. Bop, bacteriorhodopsins; Hop, halorhodopsins; SopI & II; sensory-rhodopsins. (B) Phototrophic growth of aerobic (▲) and anaerobic (■) cultures of H. walsbyi incubated in the light. (C) Photo-phosphorylation in H. walsbyi measured through light induced ATP generation (upper curve) and proton (H+) extrusion (lower curve). Phylogenetic analysis was performed using the Microbial Genome Analysis System package MiGenAS [38,39].