FIGURE 4.

The amino acid compositions for possible LUCA organisms and all other microorganisms. Clostridium (48 genomes) and Methano (51 genomes) are possible LUCA organisms, and Others (2675 genomes) are some bacteria and archaea genomes. Amino acids Q, H, C, M, and W are new amino acids and encoded by codons at average GC contents. The Methano group has less Q, H, W amino acids than others. Amino acids C and M of Methano and Clostridium are a little higher may because they have more sulfur or living in a circumstance without higher sulfur. The Methano here is short for Methanoproducents.