Some time ago an aquarium in my laboratory developed on its walls a growth of algae. Some microscope slides were placed in the aquarium in the expectation that the algae would also grow on these and that permanent preparations might be made showing the organisms in situ. On removing and staining these slides after a week's immersion, I was surprised to find, in addition to the algae, a thin and uniform coating of bacteria of various forms, some of unusual morphology”. … “It is quite evident that for the most part the water bacteria are not free floating organisms, but grow upon submerged surfaces; they are of the benthos rather than the plankton”. Arthur T. Henrici1.
These comments written in 1933 indicate, that long before the term biofim was used2, Henrici understood the basics of biofilm formation. Elsewhere in that same article Henrici showed that he had an understanding of biofilms that sounds modern even by contemporary standards.
This understanding included the facts that 1) the bacterial cells are actually growing on the slide as confirmed by the presence of microcolonies, 2) they are firmly attached to the glass slide, 3) the cells are surrounded by a matrix (sheath of gum) which holds the cells to the slide, 4) specimens from aquaria and lakes alike produced these biofilms, 5) most bacteria are not in the water column but rather are surface attached.Using techniques very much like those described by Henrici it is possible to “fish” for bacteria, algae, protozoa and microinvertebrates by placing clean glass microscope slides in an aquatic environment such as aquaria, lakes, streams, showers, the tanks of toilet bowls, and any other site where there is a large or small body of water either standing or flowing.