Bacterial Viability Assay Protocol

Bacterial viability testing was performed following the method previously described by Foerster et al. [9 (link)]. Briefly, bacterial solution was incubated in a 96-well plate. At each time point, 100 µL aliquots, which amounts to the complete volume of the wells to be tested, were transferred to another plate. Subsequently, cultures were serially diluted in seven subsequent 1:10 dilutions (20 µL culture in 180µL sterile phosphate-buffered saline (PBS) (Gibco, Lougborough, UK). Five µL droplets of every dilution were spotted on pre-dried CHOC-GC agar plates and incubated at 37 °C in a 5 % CO₂-enriched atmosphere. The density of viable bacteria, measured in colony forming units per ml (CFU/mL), was calculated from the first dilution that resulted in a countable range of 3–30 colonies.