Fluorescence microscopy image of E. coli treated with NBD-DDA.
Source: BAM, Fachbereich 4.1 Biologische Materialschädigung und Referenzorganismen
Biocides are an important component of modern hygiene measures to counteract the spread of infectious diseases. However, the overuse or improper use of biocides carries the risk that microorganisms adapt to the biocides, causing them to lose some or even all of their effectiveness, resulting in a so-called biocide resistance. A widespread class of substances within biocides are quaternary ammonium compounds (QACs). Despite their long-term use as biocides, there are still questions to be answered regarding the detailed mode of action of QACs on microorganisms. This is even more true for the mechanisms that allow microorganisms to survive the treatment with QACs and become more resistant in the long term. To ensure the long-term efficacy of QACs, it is important to answer these questions as a prerequisite for targeted countermeasures.
These questions were addressed by researchers from Division Biodeterioration and Reference Organisms in collaboration with researchers from Division Biophotonics and colleagues from the University of Queensland, Australia. In the present study, the authors first synthesized a novel fluorescent quaternary ammonium compound, termed NBD-DDA. Its fluorescence allows the "live" observation of the interaction of NBD-DDA with individual bacterial cells, e.g., under a microscope, providing a deep, quantitative insight into the mode of action of QACs.
After characterizing the antimicrobial effect of NBD-DDA on different bacterial species, and comparing it to widely used QACs (e.g., benzalkonium chloride), the authors used the fluorescence of NBD-DDA to exemplify its potential for deeper mechanistic studies. Finally, further fields of application are discussed and the possibility of adapting the synthetic pathway for the study of other compounds belonging to the group of QACs is underlined. The present study thus makes an important contribution to the understanding of mechanisms of action and resistance in biocides.
A fluorescently labelled quaternary ammonium compound (NBD-DDA) to study resistance mechanisms in bacteria
Niclas Nordholt, Kate O'Hara, Ute Resch-Genger, M. Blaskovich, Bastian Rühle, Frank Schreiber, Frontiers in microbiology 2022, Volume 13, Article number 1023326, Pages 1-13.
BAM Analytical Chemistry
BAM Biophotonics
BAM Materials and the Environment
BAM Biodeterioration and Reference Organisms