P. Angell et al., ON LINE, NONDESTRUCTIVE BIOMASS DETERMINATION OF BACTERIAL BIOFILMS BY FLUOROMETRY, Journal of microbiological methods, 18(4), 1993, pp. 317-327
The lack of on-line methodology for the determination of microbial bio
mass and activity of attached bacteria has severely limited the study
of biofilm physiology. This study showed that the fluorescent emission
of aromatic amino acids in microbial biofilms can be used to determin
e the biomass formed on 316 stainless steel coupons. Cells resuspended
from the substratum were enumerated by viable and acridine orange cou
nts showing correlation coefficients of 0.77 and 0.98, respectively, w
hen compared to the tryptophane fluorescence. Substrata treated with a
fluorescent epoxy coating (F-150) showed no fluorescence that could b
e attributed to the microorganisms. Bioluminescent emission of an acti
vely growing bioluminescent bacterium, Vibrio harveyi, was correlated
with acridine orange counts (r(2)=0.95) and fluorescence (r(2)=0.93).
The results of these studies suggest that fluorescence measurements ca
n be used to monitor microbial biomass associated with various substra
ta. Coupled with bioluminescence measurements, this method provides in
formation on both biomass constituents and metabolic activity, and the
refore possibly an indicator of sub-lethal toxicity.