The influence of electromagnetic field on morphophysiological parameters of bacterial cells evaluated through flow cytometry

Flow cytometry represents an important tool in environmental biology, and especially in cellular
biology, through its ability to distinguish among different physiological states (viable, latent and
non-viable). Flow cytometry combined with fluorescent markers, such as propidium iodide and
ethidium bromide allows to perform rapid measurements on individual cells and also
simultaneous measurements of multiple cellular parameters, both structural and functional.
The aim of this paper was to investigate the influence of the electromagnetic field on the
morpho-physiological parameters of some bacterial strains cells isolated from wastewater,
assessed through flow cytometry. In this respect, a number of 10 bacterial strains isolated from
wastewater (E. coli, Salmonella sp., Enterobacter sp., Citrobacter sp., Klebsiella sp. and
Enterococcus sp.) were exposed to an electromagnetic field (50Hz electric field at different
voltages) for 24 hours, at 37°C. Both samples, the ones exposed to electromagnetic field and
blank samples (unexposed) were assessed by flow cytometry technique. Two possible
mechanism of action have been tracked, i.e. the efflux pumps activity (fluorescence marker Ethidium Bromide) and permeabilisation of cellular layers (fluorescence marker - Propidium
Iodide). Both mechanisms of action have been identified, from slightly to significant
modifications, as compared to untreated controls, quantified as ΔMFI (median of fluorescence
intensity). Conclusion: Our results suggest that flow cytometry could be used for the real-time
evaluation of the influence of different electromagnetic fields on the aquatic microbiota, the
obtained results being of great interest for the development of technological solution with
increased efficiency in the (waste)water treatment.