1. On page 2333 line 7 – the authors state “CROMO have both the genetic and bioenergetic potential to carry out the dissimilatory sulfate reduction”. Why are the authors hedging here and saying “potential” rather than saying that the microbes are undergoing sulfate reduction? What methods, if any, could the authors have used to have more concrete evidence of which metabolisms the bacteria were using?
2. Along these lines, do the presents of transcripts for genes like dsrAB mean sulfate reduction is happening? Why or why not?
3. In figure 2, the amplicon data has been plotted from the different samples, what do the arrows signify? In other words what would you say about sample CSWold in the lower right corner versus N08-C in the upper left corner?
4. So what does this research say about the potential origin of life on Earth? Does it change your view point on where life might have originated on Earth? How might this information help with the search for life on other worlds, like Mars, or Europa?
