Abstract:
BACKGROUND: Bacteria of genus Thermus inhabit both man-made and natural thermal environments. Several
Thermus species have shown biotechnological potential such as reduction of heavy metals which is essential for
eradication of heavy metal pollution; removing of organic contaminants in water; opening clogged pipes,
controlling global warming among many others. Enzymes from thermophilic bacteria have exhibited higher activity
and stability than synthetic or enzymes from mesophilic organisms.
RESULTS: Using Meiothermus silvanus DSM 9946 as a reference genome, high level of coordinated rearrangements
has been observed in extremely thermophilic Thermus that may imply existence of yet unknown evolutionary
forces controlling adaptive re-organization of whole genomes of thermo-extremophiles. However, no remarkable
differences were observed across species on distribution of functionally related genes on the chromosome
suggesting constraints imposed by metabolic networks. The metabolic network exhibit evolutionary pressures
similar to levels of rearrangements as measured by the cross-clustering index. Using stratigraphic analysis of
donor-recipient, intensive gene exchanges were observed from Meiothermus species and some unknown sources to
Thermus species confirming a well established DNA uptake mechanism as previously proposed.
CONCLUSION: Global genome rearrangements were found to play an important role in the evolution of Thermus
bacteria at both genomic and metabolic network levels. Relatively higher level of rearrangements was observed in
extremely thermophilic Thermus strains in comparison to the thermo-tolerant Thermus scotoductus. Rearrangements
did not significantly disrupt operons and functionally related genes. Thermus species appeared to have a developed
capability for acquiring DNA through horizontal gene transfer as shown by the donor-recipient stratigraphic analysis.
