Chapter_5_spr09

Chapter_5_spr09 - Chapter 5 Environmental Influences and...

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Unformatted text preview: Chapter 5 - Environmental Influences and Control of Microbial Growth Environmental factors that affect microbial growth • Temperature • Pressure • Osmolarity • pH • Oxygen Temperature • Temperature is a major environmental factor controlling microbial growth. • ___________________ temperatures- minimum, optimum, & maximum temps for an organism • ____________________ temperature - cellular processes _____________; cytoplasmic membranes stiffen • ____________________ temperature- proteins start to __________________ • ____________________ temperature- organism grows best; between min & max • Microorganisms can be grouped by the temperature ranges they require. • • Cold: O°C–20°C • • 20°C–45°C • • 40°C–80°C • Extreme thermophiles • 65°C–113°C • Psychrophiles- found in • Example: Chlamydomonas- • Molecular adaptations of psychrophiles: • Membranes have • _______________ ________________ compared to mesophiles or thermophiles • _________________ can be used to preserve microbial cultures at ___________ • _______________ (Dimethylsulfoxide) & ___________________ are commonly used in laboratories to preserve microbial cultures for long time in freezers. • Mesophiles- • Found in ____________________________ & many terrestrial & aquatic environments. • Examples- most organisms you are familiar with such as Escherichia coli (found in the • Thermophiles • Optimum temp above • Some ____________ have been found growing at temps above • Places thermophiles are found: • soils subjected to • • • Thermus aquaticus is a common hot spring thermophile. The heat stable DNA polymerase from this bacterium is mass produced and used in laboratories to replicate DNA in a test tube. • Molecular adaptations of thermophiles: • Membranes have a • _________________ are heat stable- __________________________________ compared to mesophiles or psychrophiles Heat shock response • Occurs at high end of temperature range • • Help keep proteins from • Induced by many • Heat • High salt concentrations • Arid conditions Pressure • • Adapted to • Up to 1,000 atm • ____________________ organisms • Grow at •...
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This note was uploaded on 03/08/2009 for the course BIOL 2051 taught by Professor Brininstool during the Spring '07 term at LSU.

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Chapter_5_spr09 - Chapter 5 Environmental Influences and...

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