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Technologically important extremophiles including oil eating microbes, uranium and rocket fuel perchlorate
reduction microbes, electron producing microbes and electrode electrons feeding microbes were compared in
terms of their 16S rRNA sequences, a standard targeted sequence in comparative phylogeny studies. Microbes
that were reported to have survived a prolonged dormant duration were also studied. Examples included the
recently discovered microbe that survives after 34,000 years in a salty environment while feeding off organic
compounds from other trapped dead microbes. Shannon entropy of the 16S rRNA nucleotide composition and
fractal dimension of the nucleotide sequence in terms of its atomic number fluctuation analyses suggest a
selected range for these extremophiles as compared to other microbes; consistent with the experience of
relatively mild evolutionary pressure. However, most of the microbes that have been reported to survive in
prolonged dormant duration carry sequences with fractal dimension between 1.995 and 2.005 (N = 10 out of 13).
Similar results are observed for halophiles, red-shifted chlorophyll and radiation resistant microbes. The results
suggest that prolonged dormant duration, in analogous to high salty or radiation environment, would select high
fractal 16S rRNA sequences. Path analysis in structural equation modeling supports a causal relation between
entropy and fractal dimension for the studied 16S rRNA sequences (N = 7). Candidate choices for high fractal
16S rRNA microbes could offer protection for prolonged spaceflights. BioBrick gene network manipulation
could include extremophile 16S rRNA sequences in synthetic biology and shed more light on exobiology and
future colonization in shielded spaceflights. Whether the high fractal 16S rRNA sequences contain an asteroidlike
extra-terrestrial source could be speculative but interesting.
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