Why doesn't jam decay due to bacterial action?
The high concentration of sugar in jams keeps most bacteria from reproducing by dehydrating them.
Bacteria are the most abundant organism on earth. There are trillions of bacterial cells on you right now. In fact, due to the very small size of bacterial cells (compared to human cells), you have fewer cells than there are bacteria living on you (and in you).http://wiki.answers.com/What_is_the_most_abundant_species_on_earth&action=edit