Bacteriophage-Mediated Dispersal of Campylobacter jejuni Biofilms

ABSTRACTBacteria in their natural environments frequently exist as mixed surface-associated communities, protected by extracellular material, termed biofilms. Biofilms formed by the human pathogenCampylobacter jejunimay arise in the gastrointestinal tract of animals but also in water pipes and other industrial situations, leading to their possible transmission into the human food chain either directly or via farm animals. Bacteriophages are natural predators of bacteria that usually kill their prey by cell lysis and have potential application for the biocontrol and dispersal of target bacteria in biofilms. The effects of virulentCampylobacterspecific-bacteriophages CP8 and CP30 onC. jejunibiofilms formed on glass by strains NCTC 11168 and PT14 at 37°C under microaerobic conditions were investigated. Independent bacteriophage treatments (n≥ 3) led to 1 to 3 log10CFU/cm2reductions in the viable count 24 h postinfection compared with control levels. In contrast, bacteriophages applied under these conditions effected a reduction of less than 1 log10CFU/ml in planktonic cells. Resistance to bacteriophage in bacteria surviving bacteriophage treatment ofC. jejuniNCTC 11168 biofilms was 84% and 90% for CP8 and CP30, respectively, whereas bacteriophage resistance was not found in similarly recoveredC. jejuniPT14 cells. Dispersal of the biofilm matrix by bacteriophage was demonstrated by crystal violet staining and transmission electron microscopy. Bacteriophage may play an important role in the control of attachment and biofilm formation byCampylobacterin situations where biofilms occur in nature, and they have the potential for application in industrial situations leading to improvements in food safety.