EN: How many genes are really needed for life? The recent publication of the 160 kbp genome sequence of the symbiontic bacterium Carsonella ruddii gives new drive for the discussion of this question. I personally think that the discussions is one of the cases where we artificially try to draw a line following the human need to categorize things. The definition of how many genes are needed depends on the definition of life. Can I call an organism able to survive when testing this in an environment where I add amino acid, nucleotides etc. as supplement? Is the replication and amino acid synthesis machinery the essential factor? Well, what's then about the Mimivirus which has parts of this. The authors of the Carsonella ruddii article suggested a "organelle-like status" for the symbiont. Maybe we should accept that life is a continuum and that the question "how many genes are really needed for life" is just too unspecific.