SEM and TEM Analysis of Pdd RM-71 Cells

For SEM, exponentially growing cultures of Pdd RM-71 in TSB-1 and TSB-3 (OD₆₀₀ of 0.55) were pelleted down by centrifugation (4,000 × g, 5 minutes, 4°C). Cells were fixed as previously described (27 (link)), sputter-coated with iridium, and imaged using an Ultra Plus ZEISS scanning electron microscope. For polysaccharide capsule visualization, sample processing and TEM analyses were conducted as previously described (28 (link)). Images were digitally recorded using a CCD digital camera Orius 1100 W (Gatan). Cell length, cell width, and capsule thickness at both salinities were determined by measuring 30 cells with the Fiji software (ImageJ version 1.51n) (43 (link)). Capsule thickness for each cell was calculated as the average of six measurements at different points. An unpaired t-test was used to determine statistical significance.