Study of community dynamics
One of the strongest points of the application of
DGGE/TGGE in microbial ecology is the simultaneous
analysis of multiple samples, which allows monitoring of the
complex dynamics that microbial communities may undergo
by diel and seasonal fluctuations or after environmental
perturbations. Ward and coworkers [Cl”] were among the
first who used IXGE of 16S rDNA fragments to study population
changes in microbial communities. They examined
the seasonal distribution of community members in a hot
spring microbial mat community [ZS], and the recolonization
of bacterial populations after removal of the top 3 mm of the
community [26]. PCR-DGGE of 16S rDKA fragments has
also been used to examine seasonal changes in bacterioplankton
in coastal waters of Antarctica [27], and to study
the composition and dynamics of bacteria1 populations in
the rhizospherc of the plant chrysanthemum [28]. Recently,
van Hannen efcz/. [29] used PCR-DGGE to monitor changes
in the community composition of bacteria1 and eukaryal
microorganisms after viral lysis.
hlicrobiological. molecular and biogcochemical approaches
were combined to investigate the diurnal behavior of sulfatereducing
bacteria in the top layer of a microbial mat
community [30]. Hybridization analysis of 16s rDNA
DGGE patterns showed a filamcntous migrating sulfate
reducer affiliated to Dc.w~fomxzc. which is assumed to be
obligatory anaerobic, within and below the oxic surface layer.
Santcgoeds rtccl. [31’] combined molecular techniques and
microsensors to study the presence and activity of sulfatereducing
bacteria in biofilms from an activated sludge
basin of a wastewater treatment plant. Rlicrosensor measuremcnts
indicated that anaerobic zones dcvelopcd
within one week of biofilm formation, but that sulfate
reduction did not occur until after six weeks.
Hybridization analysis of 16s rD5JA IXGE profiles
showed that D~.w~j2wll,~s and /k.suLfovilviJ/t-io populations
were the main sulfate-reducing bacteria, and that different
populations came up at the onset of the sulfate reduction.