BIOL 2051 Lecture Notes - Lecture 5: Halobacterium Salinarum, Thermus Aquaticus, Mesophile
Document Summary
5 environmental influences and control of 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; membrane gelling; transport processes so slow that growth cannot occur. Maximum temperature- proteins start to denature; collapse of the cytoplasmic membrane; thermal lysis. Optimum temperature- organism grows best; between min & max. Microorganisms can be grouped by the temperature ranges they require: psychrophiles. Psychrophiles- found in constantly cold environments: ex: chlamydomonas- snow algae , molecular adaptations of psychrophiles. Membranes have high content of unsaturated fatty acids (semi-fluid at low temperatures) Proteins are more flexible compared to mesophiles or thermophiles. Cryoprotectants can be used to preserve microbial cultures at low temperatures. 10% dmso (dimethylsulfoxide) & 10% glycerol are commonly used in laboratories to preserve microbial cultures for long time in freezers.
