When considering the relationship of temperature to microbial life, two things must be considered: the holding temperature of the micro-organism and the length of time for which microorganisms are exposed to that temperature.
Most pathogenic microorganisms prefer temperature below 42 °C because they normally live at the body temperatures of man and animal or the air temperature experienced by plants. Some types of micro-organisms prefer either extremely cold or hot environments.
Cold temperatures often significantly slow the growth of microorganisms, which is the reason refrigeration is used to control bacterial growth.
In natural environments where micro-organisms are commonly subject to rapid changes in temperature, it is perks not surprising that they have evolved protection mechanisms.
E. coli, for example, synthesize cold shock proteins in response to a temperature down shift.
Researchers reported that, under certain conditions moderately cold storage temperature (-2 to -4 °C) resulted greatly in greater destruction of bacteria than storage at -20 C.
When cells are frozen rapidly, both intra- and extracellular fluid are freezes. Slow freezing, however, causes an intra and extracellular osmotic gradient, which can result in cellular disruption.
High temperatures usually kill most microorganisms. Steam sterilization and boiling water are two common techniques used to kill pathogenic microorganisms.
Temperature effects on pathogenic microorganisms
