Anyone see Nova Science Now tonight? One segment was on quorum sensing. QS is the concept of bacteria emitting the equivalent of a hormone to alert other bacteria (same species and other species) that they are nearby. When enough bacteria creatures are in close proximity, they form a 'quorum' (or a critical mass) and will take on the character of a swarm. What they do when they swarm depends on the species. Some glow in the dark (oooOOOooo), but others may cause a disease. Some others might swarm and kill a disease.
Check out this wiki site
and links therefrom for more info.
Why do I bring this up in an organic forum? Because there are a lot of unanswered questions in organic gardening. For example how and why, if all the necessary beneficial bacteria and fungi are living in the soil, do things sometimes go wrong; how do organic fertilizers work; why does it take 3 weeks for so many organic solutions to produce a visible effect; and for those of you using compost tea or molasses sprays, this might help explain why repeated applications are beneficial but occasional applications seemingly have no effect.