BIOL 2051 Lecture : JR - Ch. 5 Notes
Document Summary
Chapter 5 - environmental influences and control of microbial growth. Environmental factors that affect microbial growth: temperature, pressure, osmolarity, ph, oxygen. We use these to help us control microbial growth. Temperature is a major environmental factor controlling microbial growth: cardinal temperatures- minimum, optimum, & maximum temps for an organism, minimum temperature - cellular processes slow; cytoplasmic membranes stiffen. Strain 121 grows at 121 degrees celsius: psychrophiles- found in constantly cold environment. Example: chlamydomonas- snow algae : molecular adaptations of psychrophiles, membranes have high content of unsaturated fatty acid semi-fluid at low temperatures. 1: proteins are more flexible compared to mesophiles or thermophiles, cryoprotectants can be used to preserve microbial cultures at low temps. In biol 2051, the organisms are kept at 80 degrees celsius. The reason they don"t freeze is because of cryoprotectants: 10% dmso (dimethylsulfoxide) & 10% glycerol are commonly used in laboratories to preserve microbial cultures for long time in freezers, mesophiles- midrange optimum temperature.
