Recent Advances in Phototrophic Prokaryotes

Jörg Overmann, Overmann, Jörg

Phototrophic consortia currently represent the most highly developed interspecific association between prokaryotes and consist of green sulfur bacterial epibionts which surround a central, motile, chemotrophic bacterium. Several independent experimental findings indicate that a rapid signal transfer occurs between the epibionts and the central bacterium. First, the cell division of the partner bacteria occurs in a highly coordinated fashion. Second, consortia accumulate scotophobotactically in the light, whereby the central bacterium confers motility to the consortium and the epibionts act as light sensors. Third, the organic carbon uptake of the central bacterium seems to be controlled by the epibiont. A decade ago, a laboratory culture of the phototrophic consortium "Chlorochromatium aggregatum" could be established and maintained. Using "C. aggregatum," recent genomic, transcriptomic, and proteomic studies have started to unravel the molecular basis of prokaryotic heterologous multicellularity in this model system.