Both gram-positive and gram-negative bacterial species produce
extracellular hetero- or homopolysaccharides. These polysaccharides
are either permanently attached to the outer surface of
the cells or secreted into the growth medium, and are known as
capsular polysaccharides (CPS) or extracellular polysaccharides
(EPS), respectively. These bacterial polysaccharides are a focus of
study because of their importance in varied biological processes
such as bacteriaehost interaction, biofilm formation, and stress
adaptation.
Acetobacter and Gluconacetobacter species, two genera of acetic
acid bacteria (AAB), are well known for their strong ability to
oxidize ethanol to acetic acid. This oxidation process is absolutely
dependent on highly aerobic respiration using membrane-bound
enzymes. In addition, AAB can tolerate high concentrations of acetic
acid, and thus they are widely used for vinegar production. In order
to maintain a highly aerobic state, Acetobacter and Gluconacetobacter
have the ability to grow floating in static culture by producing
a pellicle on the surface of the medium. The pellicle is a
collection of cells that are tightly associated through the CPS on the
cell surface. The pellicle polysaccharides are a homopolysaccharide