During the last two years i've been working with a Comamonas
testosteroni strain which makes on plates two different types of
colonies, namely one type is producing EPS and the other type is not
producing EPS. I've called cells producing the latter type of colonies
NMCF-cells (non-mucoid colony forming); the other are MCF-cells. ON
plate cells are typically switching between the two forms, making
More interestingly, a population of cells containing the two different
forms will shift towards dominance by NMCF-cells every time stress is
being applied (e.g. hydrogen peroxide, oxidative radicals, temperature
rise, visible light, SDS, starvation, probably others ...).
NMCF-cells are also more hydrophobic than MCF-cells since they stick
better to polystyrene and to gas bubbles.
Based on these findings i've been constructing a model which allocates a
ecophysiological role for both type of cells. I would like to hear from
you if that model make sense?
I consider the MCF-cells (which are producing EPS) as the biofilm
growers. NMCF-cells could hang around in a biofilm, probably more
concentrated at the "biofilm surface" which is more exposed to
environmental stress. NMCF-cells could detach from the biofilm by
sticking to gas bubbles (produced by denitrification or photosynthesis)
and as such function as disseminators in a ecosystem. NMCF-cells could
adhere then to a fresh substratum and switch back to the EPS producing
What do you think?
Lab. Mikrobiele Ecologie, Coupure L653, 9000 GENT,Belgium
Tel: 32 9 2645976 Fax: 32 9 2646248
e-mail: peter.bossier at rug.ac.be