Biopolymers are important substrates for heterotrophic bacteria in oligotrophic freshwater environments,
but information on bacterial growth kinetics with biopolymers is scarce. The objective of this study was to
characterize bacterial biopolymer utilization in these environments by assessing the growth kinetics of Flavobacterium
johnsoniae strain A3, which is specialized in utilizing biopolymers at g liter1 levels. Growth of
strain A3 with amylopectin, xyloglucan, gelatin, maltose, or fructose at 0 to 200 g C liter1 in tap water
followed Monod or Teissier kinetics, whereas growth with laminarin followed Teissier kinetics. Classification
of the specific affinity of strain A3 for the tested substrates resulted in the following affinity order: laminarin
(7.9 102 liter g1 of C h1) maltose > amylopectin gelatin xyloglucan > fructose (0.69 102
liter g1 of C h1). No specific affinity could be determined for proline, but it appeared to be high.
Extracellular degradation controlled growth with amylopectin, xyloglucan, or gelatin but not with laminarin,
which could explain the higher affinity for laminarin. The main degradation products were oligosaccharides or
oligopeptides, because only some individual monosaccharides and amino acids promoted growth. A higher
yield and a lower ATP cell1 level was achieved at 10 g C liter1 with every
substrate except gelatin. The high specific affinities of strain A3 for different biopolymers confirm that some
representatives of the classes Cytophagia-Flavobacteria are highly adapted to growth with these compounds at
g liter1 levels and support the hypothesis that Cytophagia-Flavobacteria play an important role in biopolymer
degradation in (ultra)oligotrophic freshwater environments.