Starvation-specific formation of a peripheral exopolysaccharide by a marine Pseudomonas sp., strain S9.
The marine bacterium Pseudomonas sp. strain S9 produces exopolysaccharides (EPS) during both growth and total energy source and nutrient starvation. Transmission electron microscopy of immunogold-labeled cells demonstrated that the EPS is closely associated with the cell surface during growth (integral EPS), while both the integral form and a loosely associated extracellular (peripheral) form were observed during starvation. Formation and release of the latter rendered the starvation medium viscous. In addition, after 3 h of starvation in static conditions, less than 5% of the cells were motile, compared with 100% at the onset of starvation and approximately 80% subsequent to release of the peripheral EPS at 27 h of starvation. Inhibition of protein synthesis with chloramphenicol added before 3 h of starvation caused no increase in viscosity. However, addition of chloramphenicol at 3 h did not prevent the subsequent increase in viscosity displayed by S9 cells. The amount of integral EPS increased for both nontreated and chloramphenicol-treated S9 cells during the first hour of starvation, with a subsequent equal decrease. The chloramphenicol-treated cells, as well as cells of a transposon-generated mutant strain deficient in peripheral EPS formation, remained adhesive to a hydrophobic inanimate surface during the initial 5 h of starvation, whereas nontreated wild-type cells had progressively decreased adhesion capacity. During the initial 5 h of starvation, most of the nontreated cells but only a small fraction of the chloramphenicol-treated and mutant cells detached from the hydrophobic substratum.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of General and Marine Microbiology, University of Göteborg, Sweden.
M
M
Wrangstadh
U
U
Szewzyk
J
J
Ostling
S
S
Kjelleberg
D001426:Bacterial Proteins / Q000096:biosynthesis; D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D002701:Chloramphenicol / Q000494:pharmacology; D007124:Immunoenzyme Techniques; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D011549:Pseudomonas / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*
D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D002701:Chloramphenicol