SEM Analysis of Bacterial Cultures

The SEM analyses of bacteria grown on different culture media (A–C) were performed according to the method described by Xu et al. [45 (link)] with a few modifications as described in our previous work [44 (link)]. In brief, suspensions (2A–C) were adjusted to the concentration equivalent to no. 0.5 of the McFarland scale, centrifuged (3000× g for 10 min), fixed with glutaraldehyde (2.5%, v/v; Chempur, Piekary Slaskie, Poland), and dehydrated in a gradient ranging ethanol (30–100%, v/v; Chempur, Poland). After this, the ethanol was replaced with tert-butanol (Chempur, Poland) at room temperature. The staphylococcal samples were dried for 8 h, and coated with gold for 90 s. Bacterial cells (the average size of bacterial cells) were observed using the scanning electron microscope (Vega 3 LMU, Tescan, Brno, Czech Republic) and analyzed using Tescan Essence^TM software (Tescan, Brno, Czechia).