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#thermophiles

2 public questions tagged with this topic.

Microbial Physiology

Which of the following archaeal species does NOT contain histones?

Histones were long considered exclusive to eukaryotes, organizing DNA into nucleosomes with wrapping around octameric cores. Discovery of archaeal histones revealed evolutionary connection, yet distribution is not uniform. Euryarchaeota such as Methanothermus fervidus, Methanothermus sociabilis, and halophiles like Halobacterium salinarum encode HMf and HMt family histones that form tetramers wrapping DNA into nucleosome-like particles and regulating transcription by restricting access. These histones share histone fold motif with eukaryotic H3 and H4. In contrast, most members of Crenarchaeot

Ref: Sandman & Reeve, Curr Opin Microbiol 2006, Archaeal Histones; White & Bell, Trends Genet 2002, Chromatin in Archaea.

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Microbial Physiology

The optimum growth temperature for extreme thermophiles is:

Thermophily classification uses cardinal temperatures minimum, optimum and maximum for growth. Mesophiles optimum 20 to 45 degrees encompassing most pathogens, thermophiles 50 to 70 degrees like Bacillus stearothermophilus, extreme thermophiles also called hyperthermophiles optimum above 75 to 80 degrees growing up to 113 degrees in Pyrolobus fumarii near deep-sea hydrothermal vents where pressure keeps water liquid. Adaptations include proteins stabilized by increased ionic networks and tightly packed hydrophobic cores, chaperonins like thermosome retaining activity at high temperature, membr

Ref: Prescott's Microbiology, 11th ed., Chapter 7: Extreme Thermophiles and High Temperature Growth Optima.

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