SUBSTRATUM-INDUCED MORPHOLOGICAL-CHANGES IN A MARINE BACTERIUM AND THEIR RELEVANCE TO BIOFILM STRUCTURE

The effects of surfaces on the physiology of bacteria adhering to surf aces or immobilized within biofilms are receiving more interest. A stu dy of the effects of hydrophobic and hydrophilic substrata on the colo nization behavior of a marine bacterium, SW5, revealed major differenc es in the morphology of SW5 on these surfaces. Using epifluorescence, scanning confocal laser, and on-line visualization (time-lapse video) microscopy, the organisms at hydrophobic surfaces were characterized b y the formation of tightly packed biofilms, consisting of single and p aired cells, whereas those at hydrophilic surfaces exhibited sparse co lonization and the formation of chains more than 100 mu m long, anchor ed at the surface by the terminal (colonizing) cell. The results are d iscussed in terms of the possible factors inducing the observed morpho logical differences and the significance of these differences in terms of biofilm structure and plasmid transfer when SW5 is the recipient o rganism.