Conclusions

The take-home lesson of the first confocal microscopic images of surface attached bacterial populations was that Myxococcus isn’t so odd after all. Many, perhaps most bacteria when attached to surfaces behave in a manner much like the myxococci by producing upright structures with consistent architecture, including water channels that permit nutrient containing bulk fluid to reach well into the interior of the biofilm mass. These biofilms may also mobilize certain cells within the biofilm matrix and release them as planktonic cells capable of founding new biofilm sites.

Even more surprising is the degree of coordination apparent in mixed biofilms of two or more species. There is a degree of control not only within a species to maintain the architectural integrity of the biofilm, but there is cooperation between bacterial species to accomplish the same result. This phenomenon of coordination extends even to bacteria and their eukaryotic hosts where signals from the bacterial component (the nitrogen fixing bacterium Rhizobium for example) which alter the structure and metabolism of their host (various leguminous plants) to form an association which fixes atmospheric nitrogen, a process which neither bacterium of host can carry out by themselves.

The common feature in these associations is the activity of a large and expanding array of cell–cell signaling molecules.
The degree of coordination among and between bacteria in biofilms has led some investigators to ask if we should not consider biofilms multicellular organisms?  Well, what do you think?