are cost intensive thus
their widespread use is seriously hampered by the inability of many laboratories to
carry the high cost of fluorescence microscopes and molecular probes. Moreover, ex-
isting studies are merely focused on qualitative identification of bacteria in aerobic
and anaerobic granular activated sludge and the biomass of bacteria cannot be deter-
mined in a practical way. It seems advisable, however, to initiate close cooperation
between biotechnologists and engineers responsible for the operation of wastewater
distribution systems in the field of implementing FISH-based methods in the future,
especially in the area of practical quantitative usage.