Microbial Adaptations Flashcards
What is an extremophile?
An organism that grows optimally under 1 or more chemically/physically extreme conditions.
From what viewpoint is the term extremophile from?
An anthropocentric viewpoint.
What is the lowest temperature where microbial activity has been measured?
-40°C
How are proteins/enzymes in a microorganism adapted to psychrophily?
More alpha helices and higher polar amino acid content. Fewer ionic/hydrogen bonds.
How are cell membranes in psychrophilic microorganisms adapted?
Higher concentrations of unsaturated and short chain fatty acids.
What is the function of cold shock proteins?
They prevent formation of inhibitory mRNA and act as chaperones.
What are some examples of cryoprotectants?
Glycerol (which prevents ice crystal formation) and extracellular polysaccharide substances (EPS).
How are proteins stabilised in hyperthermophiles?
They possess highly hydrophobic cores and disulphide bonds. They are stabilised by heat shock proteins.
How is DNA stabilised in hyperthermophiles?
Reverse DNA gyrase introduces positive supercoils. DNA-binding proteins or archaeal histones help protect the DNA.
What are the stabilising lipids in Archaea and Bacteria?
Archaea = dibiphytanyl tetraether lipids. Bacteria = bacterial diether lipids.
What is a piezophile?
An organism that lives optimally at high hydrostatic pressure.
How are piezophiles adapted?
High proportion of unsaturated fatty acids in membranes.
Omph proteins - a type of porin.
What is a halophile?
An organism that grows optimally at high NaCl concentrations (>3%).
What is a moderate halophile?
An organism that grows optimally at an NaCl concentration of 3-15%.
What is an extreme halophile?
An organism that grows optimally at an NaCl concentration of 15-30%.
