On Tue, 04 Feb 1997 13:12:09 -0800 frauke hangen wrote:
.
> Hello!
>> In November 96 I got in contact with biofilms. I heard just little about this topic before and I am
very glad
> to find a special newsgroup!
>> I would like to know if there are general accepted and used terms to describe the different
three-dimensional
> structures of biofilms on solid surfaces and where I can find these terms. (I am busy with drinking
water
> organisms).
I think you will find that everyone who has done some type of
observational work on
biofilms will have thier own terms to describe the structures they see.
This is due in part
to; a) that there is no established taxanomic convention, and b) there
is a large diversity of
structures depending on the organisms, nutritional and hydrodynamic
conditions, and surfaces
studied. It might be nice if there was some agreement on definitions of
some of the structures. I
am not sure if this is something that can be organised or something that
will just evolve over time.
Here are some of the terms that Dirk deBeer, Zbigniew Lewandowski, Frank
Roe and myself have
used in papers and talks:
Cell clusters: aggregates of bacterial cells in an EPS matrix. We opted
against "microcolony" because
our structures contained more than 1 species and thought that the term
"microcolony" implied a single
species as in CFU.
Voids: spaces that separate the clusters from each other that are filled
with water or possibly very low
density EPS.
Channels: voids which have liquid flowing through them.
Streamer: a filamentous tapered structure that is a downstream extension
of a cell cluster. As far as
we can tell they only form in turbulent, or at least at high, flow. The
streamer is flexible and free to
move from side to side in the flow. Streamers are composed of bacteria
in an EPS matrix. I have
evidence to suggest that initially single sheaths of filamentous
bacteria grow from an anchor point
behind the cluster. The sheaths then become tangled and subsequently
colonized with cluster forming
bacteria.
Using the definitions above a biofilm is composed of cell clusters and
voids or channels. However, this
poses some problems when we talk about the thickness of the biofilm do
we mean the cell clusters,
the spaces in-between them or both ? I think that the channels are
important constituents of the biofilm
and should be considered as part of the biofilm rather than abscences
of biofilm.
I am sure that this topic will create much discussion.
Paul Stoodley
Exeter University
P.Stoodley at exeter.ac.uk
