The Effects of Temperature on Bacterial Growth

Bacteria can grow at a wide range of temperatures. The effects of temperature depend on what kind of bacteria you are dealing with.

University Study of Temperature on Bacteria

• A study by students at James Madison University in Harrisonburg, Virginia, exposed escherichia coli (E. coli) and bacillus megaterium to three high temperatures: 27 degrees C or 80 degrees F, 37 degrees C or 98 degrees F and 42 degrees C or 108 degrees F. Both bacteria were grown best at the lowest of the temperatures.

Different Temps For Different Bacteria

• Bacteria are grouped into three categories for optimum temperature-based growth: psychrophiles or psychrophilic, mesophiles or mesophilic and thermophiles or thermophilic. Phileo in the Greek means "lover of." Psychro- means "low temperature."

  Psychrophilic bacteria are bacteria that grow best in low temperatures, such as 32 to 68 degrees F (0 to 20 degrees C). Examples of psychrophilic bacteria are basic soil bacteria like arthrobacter and psychrobacter. Arthrobacter is bacteria with nutritional and medical benefits, but psychrobacter is a culprit in diseases like meningitis.

  Mesophilic bacteria grow best in lukewarm to cool warm temperatures, 77 to 113 degrees F (25 to 45 degrees C).

  Thermophilic bacteria grow best in warm to hot temperatures, such as 122 to 158 degrees F (50 to 70 degrees C). Examples of thermophilic bacteria are bacillus flavothermus and thermus aquaticus. Bacillus flavothermus is a spore-forming bacteria found in soils. Thermus aquaticus lives in hot water. It is a very important bacteria that aids in the coding, recoding and reproduction of DNA and RNA.

  Hyperthermophilic bacteria will grow extreme heat, 158 to 230 degrees F (70 to 110 degrees C).

Extreme Freezing

• Extreme freezing can stop bacterial growth and/or kill bacteria altogether. From -30 degrees C and below, bacteria growth slows rapidly. This is helpful in knowing how to store foods, especially foods kept in schools, restaurants and hospitals.

Extreme Heating

• Extreme heat would also stop bacterial growth and/or kill bacteria altogether. The highest temperature above the optimum for any bacteria would inhibit growth or kill the bacteria. A higher temperature than the highest optimum temperature for a hyperthermophilic bacterium would stop the reproduction of that bacterium.

Real-Life Applications

• If a bacteria is in your body, it will thrive until your body spikes a fever (the body raises its own temperature) to kill the bacteria. Still, your body temperature can only go so high---that is why antibiotics are sometimes needed to kill harmful bacteria.

  When a meat product is on display in a supermarket, the heat of the lighting of the display area increases the bacterial growth and promotes a more rapid decay of the meat.

  Hospitals normally keep the central air conditioning low because it inhibits the growth of bacteria in the rooms of the patients. Consequently, there is less chance for infection for patients.

Significance

• It is important to know how temperature affects bacterial growth, so that disease can be prevented or eradicated, food can be preserved longer and lives can be saved.