Tetrazolium reduction assays, phospholipid analysis, and 16S rRNA (rDNA) se
quence analysis were applied to assess the distribution, composition and ac
tivity of microbial communities developing in biofilters treating non-ozona
ted and ozonated drinking water, The response of media-attached biomass to
both operating temperature (3 degrees C vs. > 12 degrees C) and ozone appli
cation point was assessed. As judged by 2-(p-iodo-phenyl)-3-(p-nitrophenyl)
-s-phenyl tetrazolium chloride (INT) reduction, the dehydrogenase activity
in biofilter systems that were operated with non-ozonated water was 55% low
er than in identical filters operating with ozonated water. There was no si
gnificant difference between the microbiological activity measured in a bio
filter series treating ozonated water and an identical series where ozonate
d water was introduced at an intermediate point. The biomass levels in biof
ilter systems that were operated with ozonated water were 47% higher on ave
rage than identical systems operated with non-ozonated water. Operating tem
perature had no significant impact on total biomass levels however, specifi
c dehydrogenase activity was 70% higher in systems operated at ambient temp
eratures ( > 12 degreesC) than in systems held at 3 degrees C. Phospholipid
and rDNA analysis suggests that there was a community structure response t
o ozone application and operating temperature, but no response to different
ozone application points. (C) 2001 Elsevier Science Ltd. All rights reserv
ed.