Results
Biofilm structure by SEM
Visual examination of the samples showed that the stony
substrates were fouled with dense brown hemispherical colonies
1–5 mm in diameter located close to each other. The
densest fouling by colonies was observed on the control
stone, while experimental plates were fouled with thin green
and brown biofilms between colonies. Unlike the stony
substrates, the steel plate was completely covered with thin
green and brown biofilms. Scanning electron microscopy
showed that colonies contained long vertically oriented trichomes
enclosed in mucilaginous sheaths. Filaments were
adjoined close to each other and interspersed with coccoid
and rod-shaped bacterial cells submerged in mucilage (Figs.
1A–1B), as well as diatom frustules (Fig. 1C) that sometimes
formed a dense layer on the top surface of the colony
(Fig. 1D). The biofilm from the steel plate showed minimal
vertical development and contained short filaments and
coccoid cells surrounded by mucilage and diatom frustules
embedded in the biofilm matrix (Figs. 1E–1F).