Growth and biocide susceptibility of environmental mixed species biofilms

The ubiquitous nature of biofilms in industrial flow systems creates a need to understand how microbial organisms affect the growth and susceptibility to chemical biocides of different species. The Calgary Biofilm Device (CBD) is an ideal system to study these parameters and allows for rapid and reproducible testing of multiple, equivalent biofilms. The device was amenable to the study of mixed populations and identified their planktonic and biofilm growth characteristics. The CBD was used to study the susceptibilities of these populations to industrial biocides and the differences between organisms grown in pure culture and as members of mixed consortia. Biocides were effective against planktonic organisms and increased their efficacy as contact time increased. Biofilm organisms displayed increased resistance to biocides, which is also affected by contact time. Mixed planktonic populations showed little change in biocide susceptibility, but mixed biofilm populations were protected better than individual biofilms.