Attachment of Pseudomonas fluorescens to glass and influence of electrolytes on bacterium-substratum separation distance.
The influence of Na+, Ca2+, La3+, and Fe3+ on the adhesion of Pseudomonas fluorescens H2 and H2S was investigated with interference reflection microscopy (IRM). IRM is a light microscopy technique which allows (i) visualization of the adhesive sites of living bacteria as they attach to a glass cover slip surface and (ii) evaluation of the bacterium-glass surface separation distance within a range of 0 to ca. 100 nm. The addition of each cation caused changes in IRM images consistent with a decrease in the separation distance, and minimum effective concentrations were as follows: Na+, 1 mM; Ca2+, 1 mM; La3+, 50 microM; and Fe3+, 50 microM. With strain H2, the effects of Na+, Ca2+, and La3+ were fully reversible in that the separation distance increased again when the electrolyte was replaced with distilled water. However, with strain H2S, a spontaneous mutant of H2 with increased attachment ability, only the effect of Na+ was fully reversible, and the effects of Ca2+ and La3+ were only partially reversible or irreversible. The effect of Fe3+ was irreversible with both strains, but this may be related not only to the electrolytic nature of Fe3+ but also to the decrease in solution pH to 3.5 caused by its addition. It is proposed that the electrolytes caused a decrease in separation distance by neutralizing negative charges on bacterial surface polymers and that the different effects obtained with the two strains are related to their different adhesion abilities.
D001422:Bacterial Adhesion / Q000187:drug effects*; D002118:Calcium / Q000494:pharmacology; D004573:Electrolytes / Q000494:pharmacology*; D005898:Glass; D007501:Iron / Q000494:pharmacology; D007811:Lanthanum / Q000494:pharmacology; D008857:Microscopy, Interference; D009068:Movement; D011551:Pseudomonas fluorescens / Q000502:physiology*; D012964:Sodium / Q000494:pharmacology
D004573:Electrolytes; D007811:Lanthanum; D012964:Sodium; D007501:Iron; D002118:Calcium