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Applied and Environmental Microbiology, October 2001, p. 4638-4647, Vol. 67, No. 10
Department of Applied Chemistry and
Microbiology, University of Helsinki, 00014 University of
Helsinki,1 and Finnish Institute of
Marine Research, 00931 Helsinki,2 Finland
Received 3 May 2001/Accepted 2 July 2001
Cyanobacteria of the genus Nodularia form toxic
blooms in brackish waters worldwide. In addition,
Nodularia spp. are found in benthic, periphytic, and
soil habitats. The majority of the planktic isolates produce a
pentapeptide hepatotoxin nodularin. We examined the morphologic,
toxicologic, and molecular characters of 18 nodularin-producing and
nontoxic Nodularia strains to find appropriate markers
for distinguishing the toxic strains from the nontoxic ones in field
samples. After classical taxonomy, the examined strains were identified
as Nodularia sp., Nodularia spumigena,
N. baltica, N. harveyana, and N.
sphaerocarpa. Morphologic characters were ambiguous in terms of
distinguishing between the toxic and the nontoxic strains. DNA
sequences from the short 16S-23S rRNA internally transcribed spacer
(ITS1-S) and from the phycocyanin operon intergenic spacer and its
flanking regions (PC-IGS) were different for the toxic and the nontoxic
strains. Phylogenetic analysis of the ITS1-S and PC-IGS sequences from
strains identified as N. spumigena, and N.
baltica, and N. litorea indicated that the
division of the planktic Nodularia into the three
species is not supported by the ITS1-S and PC-IGS sequences. However, the ITS1-S and PC-IGS sequences supported the separation of strains designated N. harveyana and N.
sphaerocarpa from one another and the planktic strains.
HaeIII digestion of PCR amplified PC-IGS regions of all
examined 186 Nodularia filaments collected from the
Baltic Sea produced a digestion pattern similar to that found in toxic
isolates. Our results suggest that only one planktic Nodularia species is present in the Baltic Sea plankton
and that it is nodularin producing.
0099-2240/01/$04.00+0 DOI: 10.1128/AEM.67.10.4638-4647.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Diversity of Toxic and Nontoxic Nodularia Isolates
(Cyanobacteria) and Filaments from the Baltic Sea

*
Corresponding author. Mailing address: Department of
Applied Chemistry and Microbiology, Viikki Biocenter, P.O. Box 56, 00014 University of Helsinki, Finland. Phone: 358-9-19159270. Fax:
358-9-19159322. E-mail: kaarina.sivonen{at}helsinki.fi.
Present address: Centre de Recherche Public, Gabriel Lippmann,
Cellule de Recherche en Environnement et Biotechnologies, L-1511 Luxembourg, Luxembourg.
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