Aerobic anoxygenic phototrophic bacteria in Antarctic sea ice and seawater

Aerobic anoxygenic phototrophs are obligate aerobes with unusually high concentrations of carotenoids, low cellular contents of bacteriochlorophyll-a and they lack light-harvesting complex II. In this study, sea ice and seawater samples were collected from six different sites in the Ross Sea, Antarctica. Using a combination of primers for pufM (which encodes a pigment-binding protein subunit of the reaction centre complex), clone libraries of DNA and cDNA were created and a total of 63 positive clones were obtained from three sites, all clustering within the a-Proteobacteria. Fifty-three of these clones were from seawater. The remaining clones were from sea ice and all were found in the middle and bottom sections of the ice. These sea ice bacteria may favour the lower part of the ice matrix where irradiance is low. This report highlights the first findings of AAnPs in antarctic sea ice and seawater within the Ross Sea Region.