A total of 10 individual plasmid preparations from the second-round selection were sequenced. All 10 sequences of the encoded GRLMR mutants were identical, containing the two-point mutations (L314H and D408E) that were characterized above. We thus reasoned that GRLMR variants had converged to the most fit variant throughout the two rounds of selection. This GRLMR variant (SeR) was fully characterized as described above.