C. Freeman et Ma. Lock, THE BIOFILM POLYSACCHARIDE MATRIX - A BUFFER AGAINST CHANGING ORGANICSUBSTRATE SUPPLY, Limnology and oceanography, 40(2), 1995, pp. 273-278
In contrast to the widely held view that microorganisms respond rapidl
y to changes in environmental conditions, the microbes in biofilms app
ear remarkably resilient to substantial changes in the abundance of di
ssolved organic substrates. Removal of high-molecular-weight dissolved
materials from waters supplied to river biofilms generally did not af
fect bacterial densities or the synthesis of phospholipids and DNA. Ev
en the complete elimination of exogenous materials from the overlying
waters allowed heterotrophic activity to continue unaffected. Moreover
, that continued activity was not supported by the catabolism of endog
enous reserves of C (poly-beta-hydroxy alkanoate-PHA). The addition of
inorganic nutrients to substrate-free waters allowed heterotrophic ac
tivity to increase within the biofilm. Since neither exogenous sources
of river DOC or endogenous reserves (PHA) served as the source of C,
we propose that an alternative, namely the polysaccharide matrix (and
any absorbed or incorporated organic matter), served as the primary ca
rbon reserve for biofilm microorganisms during the imposed organic sub
strate deprivation.