Biofilms systematics

enigl at aol.com enigl at aol.com
Thu Jan 23 20:01:36 EST 1997

In article <5bqlja$eg8 at mserv1.dl.ac.uk>, Nikolai Bugaenko
<bugar at post.krascience.rssi.ru> writes:

> The main idea I want to stress is
>that one should avoid to misusage of an analogy between an organism and
>a group of individuals.>>

I see biofilms as an organism with top layer cells collecting nutrients
the cells deeper in the biofilm.  There even seems to be communications
between these cells because when the inner cell are starving the outer
increase the in flow of nutrients to the inner cells.  This is definitely
community if not an organism.  I see a 3-D structure in the biofilms I

1.  Dead or injured (viable but not culturable (VBNC)?) layer of cells
2.  Aerobic or facultative cells
3.  Anaerobic cells
4.  Attachment cells,  sometimes VBNC?

In a water pipe line biofilm, the outer cells also seem to function like
epidermis or cap layer, in that those cells are dead and protect the inner
cells from antimicrobial agents.  Each cell type seems to have its own
function:  attachment cells, anaerobic cells are protected by upper layer
cells and the dead outer layers protect the rest from antimicrobials.  

The biofilms I see in the environment are many species and never pure
cultures.  The pure culture biofilms I have encountered have been in human
infections, e.g., urinary track,  blood, CSF systems.  

I read a little article about microorganisms as organisms in an issue of _
The Sciences_ some years ago and I would be pleased if some one can find
reference.  I will try to find it also.  

> First of all, an organis consists of the
>specialized cells which fail to survive without another ones.>>

That is not true for slime molds, Myxomycophyta.

> Yes, there
>exist few species with the similar behavior, but it looks like an
>exclusion. >>

I have seen it more like the rule not exclusion.

All biofilms in the environment I have seen consist of specialized cells
unable to survive without the rest of the biofilm being present.  The
anaerobes are the best example.   The _Pseudomonas_ in water pipe lines
to need protection from a layer of dead cells over them.  Then the inner
(lowest-deepest) cells are differentiated with specialized attachment
structures to keep the middle cells within the glycocalex and not float
freely as planktonic cells, thus disrupting the biofilm itself.

The biofilms I deal with look much more like an organism by definition,
not.  e.g., Cell communication, multiple species of cells,  cell
differentiation within the species.  To me they are at least between a
community and an organism,  if not a fully developed organism.  They (so
;-)  ) have not built specialized reproduction structures as the slime
have done,  but they may yet evolve that way given time (or have they
done that :-), is that how we came in to being?)

Scientific American has an article on bacterial communication this month,
I have not read it yet.  It could relate to biofilms.

Davin C. Enigl, (Sole Proprietorship) MEAS

Microbiology Consulting,  Hazard Analysis and
Critical Control Points (HACCP), CGMP, and Validations
for the Food, Cosmetic, Nutritional  Supplement, and Pharmaceutical

enigl at aol.com

January 23, 1997
4:01 pm

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