The rate and character of spontaneous mutation in Thermus thermophilus

Selection of spontaneous, loss-of-function mutations at two chromosomal loci (pyrF and pyrE) enabled the first molecular-level of replication fidelity in the extremely thermophilic bacterium Thermus thermophilus. Two different methods yielded similar mutation rates, mutational spectra determined by sequencing of independent mutants revealed a variety of replication errors distributed throughout the target genes. The genomic mutation rate estimated from these targets, 0.00097 +/- 0.00052 per replication, was lower than corresponding estimates from mesophilic microorganisms, primarily because of a low rate of base substitution.. However, both the rate and spectrum of spontaneous mutations T. thermophilus resembled those of the thermoacidophilic archaeon Sulfolobus acidocaldarius, despite important molecular differences between these two thermophiles mid their genomes.