Monitoring Bacterial Growth Activity in Biofilms from Laboratory Flow Chambers, Plant Rhizosphere, and Animal Intestine

It has become evident from investigations carried out in recent years that bacteria growing on surfaces tend to build up heterogeneous communities in which different species may reside, interact, and perhaps exchange information. Many cellular activities reflect the growth status of the cell, but one process, more than most others, has become the choice of target for quantification when estimating the growth activity of the cell—the translation process. This part of the cellular macromolecular synthesis is the most complicated and the most resource demanding, and is obviously a highly regulated process. A frequently used laboratory biofilm system involves a flow-chamber setup. Several variations exist with two prominent major types, the modifed Robbins device (MRD) and the mini flow chamber. The MRD consists of flow chambers with immersed sample holders, each holding a piece of substratum for biofilm growth. The disadvantage of the MRD is that it is not possible to study the biofilm on the coupons unless they are removed from the device. The mini flow chambers are established as small milled channels in Plexiglas covered with microscope cover-slip glasses serving as substrata. The biofilms growing in the mini flow chambers can easily be observed microscopically. The disadvantages of the mini-flow-chamber system are that it may be difficult to get physical access to the biofilm without an embedding step, and flow rates are somewhat limited because of the thin cover-slip substratum.