The discussion centers on NASA's discovery of arsenic-based life forms, specifically microbes found in Mono Lake, California, which can utilize arsenic as an energy source. Previous research published in 2008 by Kulp et al. in the journal Science identified similar arsenic-metabolizing microbes, revealing their ability to perform photosynthesis using arsenite. The 2010 study by Wolfe-Simon introduced a different microbe capable of incorporating arsenic into its biomolecules, marking a significant finding in astrobiology. These studies collectively highlight the ancient nature of microbial arsenic metabolism and its implications for understanding life's adaptability.
PREREQUISITESResearchers in astrobiology, microbiologists studying extremophiles, and environmental scientists interested in microbial metabolism and its implications for life beyond Earth.
Kulp et al. (2008) Arsenic(III) Fuels Anoxygenic Photosynthesis in Hot Spring Biofilms from Mono Lake, California. Science 321: 967. http://dx.doi.org/10.1126/science.1160799Abstract
Phylogenetic analysis indicates that microbial arsenic metabolism is ancient and probably extends back to the primordial Earth. In microbial biofilms growing on the rock surfaces of anoxic brine pools fed by hot springs containing arsenite and sulfide at high concentrations, we discovered light-dependent oxidation of arsenite [As(III)] to arsenate [As(V)] occurring under anoxic conditions. The communities were composed primarily of Ectothiorhodospira-like purple bacteria or Oscillatoria-like cyanobacteria. A pure culture of a photosynthetic bacterium grew as a photoautotroph when As(III) was used as the sole photosynthetic electron donor. The strain contained genes encoding a putative As(V) reductase but no detectable homologs of the As(III) oxidase genes of aerobic chemolithotrophs, suggesting a reverse functionality for the reductase. Production of As(V) by anoxygenic photosynthesis probably opened niches for primordial Earth's first As(V)-respiring prokaryotes.