Chip-calorimetry provides real time insights into the inactivation of biofilms by predatory bacteria

Abstract

Control or removal of undesired biofilms has frequently been found to be quite difficult. In addition to biocidal or antibiotic chemicals or materials designed to prevent biofouling, biological control agents appear to be promising. Reports of bacterial predators eradicating biofilms or eliminating pathogens motivate a more systematic screening of biofilm-eliminating bacterial predators. Unfortunately, the analysis of the eradication process is demanding. In the present study, chip-calorimetry was applied to monitor the elimination of Pseudomonas sp. biofilms by Bdellovibrio bacteriovorus. The method uses metabolic heat as a real-time parameter for biofilm activity. The method is non-invasive, fast and convenient due to real-time data acquisition. In addition, heat-production data can reveal information about the energetics of the predator–prey interaction. The calorimetric results were validated by confocal laser scanning microscopy. The approach described may be useful for the screening of biofilm susceptibility to different predators.

Keywords:

• biofilm
• calorimetry
• biological control agent
• Bdellovibrio
• predator–prey interaction

Acknowledgments

The authors thank the German Research Council (Deutsche Forschungsgemeinschaft, DFG) for supporting this work (grant number Ma 3746/2-3).