3. Modern molecular techniques for the analysis of
toxic cyanobacteria
The diversity of toxic cyanobacteria has been traditionally
studied by direct microscopy and isolation of
respective strains. Recent developments of molecular tools
(Fig. 4) have increased our awareness of the limitations of
the traditional techniques, which tend to underestimate
the in situ diversity of cyanobacteria. The reasons include
(a) the lack of conspicuous traits of toxic cyanobacteria,
especially the unicellular and simple filamentous types and
(b) the isolation of opportunistic strains. Therefore, it is
difficult to morphologically distinguish between toxic and
non-toxic cyanobacteria that might coexist in the same site.
Morphological features did not show a good correlation
with toxicity, as the properties traditionally used for
species identification of cyanobacteria occur in toxic and
non-toxic strains alike. Therefore, enrichment cultivation
was, and still remains, an essential tool in the study of toxic
cyanobacteria, because it enables us to perform physiological
and biochemical studies on the isolates, including
the presence and expression of toxin-coding genes.
3. Modern molecular techniques for the analysis of
toxic cyanobacteria
The diversity of toxic cyanobacteria has been traditionally
studied by direct microscopy and isolation of
respective strains. Recent developments of molecular tools
(Fig. 4) have increased our awareness of the limitations of
the traditional techniques, which tend to underestimate
the in situ diversity of cyanobacteria. The reasons include
(a) the lack of conspicuous traits of toxic cyanobacteria,
especially the unicellular and simple filamentous types and
(b) the isolation of opportunistic strains. Therefore, it is
difficult to morphologically distinguish between toxic and
non-toxic cyanobacteria that might coexist in the same site.
Morphological features did not show a good correlation
with toxicity, as the properties traditionally used for
species identification of cyanobacteria occur in toxic and
non-toxic strains alike. Therefore, enrichment cultivation
was, and still remains, an essential tool in the study of toxic
cyanobacteria, because it enables us to perform physiological
and biochemical studies on the isolates, including
the presence and expression of toxin-coding genes.
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