Figure 2

Ultra-thin section electron micrograph of cells of D. hafniense Y51 (A) and PCE-S (B). Cm: cytoplasmic membrane, Cw: cell wall, Cy: cytoplasm, Ss: slime sacculus (mucosal layer). Cells were grown in the presence of PCE and harvested in the late exponential growth phase. Cells were pre-fixed with 2.5% glutaraldehyde for 1 h and post fixed with 1% osmium tetroxide for 2 h. Samples were dehydrated in ascending ethanol series and embedded in Araldite resin. Ultra-thin sections were prepared with an ultramicrotome (Ultratome III, LKB Produkter AB, Bromma, Sweden) and analysed in a Zeiss EM902A transmission electron microscope (Carl Zeiss AG, Oberkochen, Germany).