Biology Reference
In-Depth Information
Figure 8:
Schematic representation of secondary metabolite gene clusters in
Microcystis aeruginosa
PCC 7806. (A) Gene clusters
encoding non-ribosomal peptide synthetases (NRPS) and polyketide synthases (PKS). The names assigned to individual
genes in
M
.
aeruginosa
PCC 7806, or to genes that were characterized in other cyanobacterial strains are indicated above the
arrows. Products assigned to the respective pathways are shown on the right. (B) Gene cluster encoding enzymes potentially
involved in a patellamide-like pathway. Names of patellamide biosynthesis genes are indicated above the arrows. Gene
identifi ers in the
M
.
aeruginosa
PCC 7806 genome are indicated below the arrows. With the kind permission of Tandeau
de Marsac, Institut Pasteur, Unité des Cyanobactéries; CNRS, URA2172, F-75015, Paris, France [Frangeul
et al.
(2008)
BMC
Genomics
9:
274; doi:10.1186/1471-2164-9-274].
Color image of this figure appears in the color plate section at the end of the topic.
Effect of light on MC production has been studied by various workers (Gorham, 1964; Watanabe
and Oishi, 1985; van der Westhuizen
et al
., 1986; Codd and Poon, 1988). Van der Westhuizen and
Eloff (1985) reported that increase of light intensity enhanced toxin production by
M
.
aeruginosa
.
Four-fold increase in the MC content of
M
.
aeruginosa
in batch cultures was observed with an
increase in light intensity from 7.53 microeinsteins m
-2
s
-1
to 30.1 microeinsteins m
-2
s
-1
(Watanabe
and Oishi, 1985). The toxicity in these studies was reported to be independent of light intensity and
toxicity was assayed by determining 50% lethal dose in a mouse bioassay. On the contrary, Utkilen
and Gjolme (1992) reported a 2.5 fold increase in toxicity of
M
.
aeruginosa
CYA 228/1 in continuous
cultures when the light intensity was increased from 20 to 40 microeinsteins m
-2
s
-1
but further
increase in light intensity did not enhance the toxicity. These observations cannot be compared with
