Bio films
A biofilm is a structured community of microorganisms encapsulated within a self-developed polymeric matrix and adherent to a living or inert surface (Costerton et al., 1995)
Biofilms are a common occurrence in all aquatic associated environments however they are not usually noticed until there is cause for concern after an investigation. Generally the investigation has been centred on sporadic results from Coliforms being found in the water. Variable positive/negative results for Coliforms can often indicate the presence of biofilm growth which is harbouring a wide variety of both pathogenic and non-pathogenic bacteria.
Biofilms act and resemble a mat of bacteria joined together in a complex interdependent fashion. The biofilm adheres to the surface of whatever system it is in. Periodically some of the biofilm breaks away into the water and will either end up as contaminant that escapes to the consumer or will block all physical filters over time. Pseudomonas spp. are a big contributor to biofilms and are normally accompanied by other normal gram negative suspects associated with water contamination e.g. E.coli and Salmonella spp. (both indictors of faeces). Protozoa, fungi and algae often accompany these bacterial biofilms.
Costerton, J.W., Lewandowski, Z., Caldwell, D.E., Korber, D.R., and Lappin-Scott, H.M. (1995) Microbial biofilms. In Annual Review of Microbiology, Vol. 49. Ornston, L.N., Barrows, A., and Greenberg, E.P. (eds). Palo Alto, CA: Annu Rev Inc, pp. 711–745.