|MadSci Network: Microbiology|
Pickles that are bottled on the shelf in grocery stores don't have bacteria in them. The bacteria have been killed by cooking.
Pickles that are in the refrigerated section of the grocery store do have bacteria, and the bacteria are similar to that in yogurt.
The bacteria in pickles, yogurt and sauerkraut make your intestines (colon) healthier by keeping down disease related bacteria.
These bacteria are called "lactic acid bacteria", because they make lactic acid when they grow with no oxygen present. Some other bacteria make acetic acid (vinegar) or other acids instead, and are also good for your digestion.
These bacteria stop or slow the growth of bad bacteria, and so keep pickled foods from spoiling fast.
Try the links in the MadSci Library for more information on Microbiology.