MICRB265 Lecture Notes - Lecture 34: Thermophile, Bioremediation, Radioresistance
23 Dec 2017
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Low aw limit for living organisms = 0. 61 if aw is less than 0. 61 then there should be no living. Dna is disordered at 0. 55 aw. the vapour pressure of pure water. organisms. Categories of extremophiles (temperature, ph osmotic, hydrostatic, desiccation, radiation). Temperature: effect of temperature on normal growth. Profound effect on viability enzyme-catalyzed reactions sensitive to temperature. High temperatures; membrane disruption, enzyme denaturation, dna denaturation. Freezing temperatures; membranes become gel-like, no separation between phospholipid and. Psychrotolerant can grow at 0c, but have mesophilic optimum of 20-40c. protein domains; structure is homogenized. 3. extremophiles (bacteria that can adjust to mesophilic). Martian microbe colonized earth from meteorite. high radioresistance evolved in cycled process (100 cycles) of high dose irradiation/recovery of population. Hypothesis process couldn"t occur on earth but could take place in subsurface layers of polar regions of mars. In us, 70 million metres cubed of soil and 3 trillion litres of groundwater had been contaminated.
