Bacterial capsule production has received considerable attention in medical microbiology and in biotechnology
while there is only very limited information available on the role of the polysaccharidic capsule production in
natural bacterial assemblages. For marine bacterioplankton, representing the largest living surface in the ocean, it
has been shown that a capsular envelope frequently surrounds the bacterial cell and that the presence of this
capsule is highly correlated with metabolic activity. The matrix of the capsule is formed by polysaccharide fibrils
which are anchored in the outer membrane of the cell by ionic interactions of the unsubstituted polysaccharide
chains or by hydrophobic interactions between lipid-substituted polysaccharide molecules. Hydrophobicity
therefore should change when the bacterial cell enters a different state of activity i.e. dormancy.
In this study, the role of the capsule for marine bacterioplankton in regulating hydrophobicity and its ecological
consequences should be determined. First of all, the hydrophobicity of bacterioplankton in different growth stages
and under different nutrient conditions should be assessed together with the quantification of capsule formation.
Additionally, the production of the capsular envelope by bacteria grown under different nutrient conditions will be
quantified. Subsequently, the possible link should be established between the formation of a capsule and the
expression of hydrophobicity in natural marine bacterioplankton communities.
Specific attention should be paid to the alteration of hydrophobicity and the capsular envelope regarding different
growth stages and different nutrient conditions.