The efficacy of many commonly used biocides is often determined by laboratory evaluations against a variety of planktonic microorganisms. While these tests provide some information as to the performance of a biocide against a particular microorganism, they may not predict how well the biocide will perform under actual field conditions against the more problematic sessile form of the organisms. In order to address the issue of how well a biocide penetrates and kills the problematic
microorgmisms contained within a biofilm, an artificial biofilm system utilizing microorganisms embedded in olginate beads has been used to compare the efficacy of biocide treatments against both the planktonic and sessile form of the same organism. Pure cultures of Enterobacter aerogerres, as well as mixed field isolates, were used in the experiments. In addition, the alginate beads were prepared with actual system waters taken from a variety of industrial applications. In that way, all of the scale and corrosion inhibitors and other contaminants which are present in the actual system are also present in the model biofilm system. In all cases, the organisms contained within the artificial biofilm were significantly more difficult to kill than the corresponding plonktonic microbes.
Keywords: alginate, biocide, biotilm, glutaraldehyde, microbially induced corrosion, plaoktorric, sessile, SRB, sulfate reducing bacteria