BIOL 2051 Chapter : Chapter5 Outline
Document Summary
Chapter 5 - environmental influences and control of microbial growth. Environmental factors that affect microbial growth: temperature, pressure, osmolarity, ph, oxygen. Temperature is a major environmental factor controlling microbial growth. _cardinal temperatures (3)_ temperatures- minimum, optimum, & maximum temps for an organism. _minimum_ temperature - cellular processes _slow down_; cytoplasmic membranes stiffen. _optimum_ temperature- organism grows best; between min & max: microorganisms can be grouped by the temperature ranges they require, psychrophiles (cold) unsaturated fatty acids, cold: o c 20 c (32 -68 f, mesophiles (mid-range/moderate temperature, 20 c 45 c (68 -113 f) Thermophiles (hot) saturated fatty acids: 40 c 80 c (104 -176 f) Extreme thermophiles (really hot: 65 c 113 c (149 -235. 4 , psychrophiles - found in constantly cold environments. Example: chlamydomonas- snow algae , makes snow pink: molecular adaptations of psychrophiles, membranes have high content of unsaturated fatty acids - semi-fluid at low temperatures. _cryoprotectants_ can be used to preserve microbial cultures at _low temps_
