Bacillus stearothermophilus
Bacillus stearothermophilus is a gram positive, heat resistant spore-forming rod. This bacterium can survive high temperatures between 130 – 145°C and grows well in high temperatures such as 55oC. Which is whay it is found in warm compost piles.
This is a cross section (a view of a slice of the middle) of a spore of Bacillus stearothermophilus. Spores of bacteria allow the bacteria to survive harsh conditions until the time when the bacterium can thrive and reproduce.
The heat resistance property comes from the spore which allows the bacterium to survive the harsh condition. It remains in a non-germinating dormant state until a favourable temperature (43 to 75°C) is reached. The spore is then activated by a process called heat shock thereby enabling the spore to germinate into a vegetative cell and hence reproduce.
Bacillus stearothermophilus has been known to cause spoilage in many Ultra High Temperature (UHT) processed foods such as milk and dairy products.
