The aim of this study was to assess the phylogenetic relationships, ecology and ecophysiological characteristics of the dominant planktic algae in ice-covered lakes on James Ross Island (northeastern Antarctic Peninsula). Phylogenetic analyses of 18S rDNA together with analysis of ITS2 rDNA secondary structure and cell morphology revealed that the two strains belong to one species of the genus Monoraphidium (Chlorophyta, Sphaeropleales, Selenastraceae) that should be described as new in future. Immotile green algae are thus apparently capable to become the dominant primary producer in the extreme environment of Antarctic lakes with extensive ice-cover. The strains grew in a wide temperature range, but the growth was inhibited at temperatures above 20 °C, indicating their adaptation to low temperature. Preferences for low irradiances reflected the light conditions in their original habitat. Together with relatively high growth rates (0.4-0.5 day-1) and unprecedently high content of polyunsaturated fatty acids (PUFA, more than 70% of total fatty acids), it makes these isolates interesting candidates for biotechnological applications.
- Klíčová slova
- Antarctica *, Ecology *, Fatty acids *, Ice-covered lakes *, Light *, Monoraphidium *, Phylogeny *, Temperature *,
- MeSH
- biodiverzita * MeSH
- Chlorophyta klasifikace genetika metabolismus MeSH
- fytoplankton klasifikace genetika izolace a purifikace metabolismus MeSH
- fyziologická adaptace MeSH
- jezera MeSH
- ledový příkrov * MeSH
- nenasycené mastné kyseliny metabolismus MeSH
- RNA ribozomální 18S genetika MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Antarktida MeSH
- Názvy látek
- nenasycené mastné kyseliny MeSH
- RNA ribozomální 18S MeSH
The environmental occurrence and concentrations of cyanobacterial toxins (cyanotoxins) were investigated in the Czech Republic. Concentrations of microcystins (MCs), cylindrospermopsin (CYN) or saxitoxins (STXs) were determined immunochemically by ELISA assays in 30 water samples collected from the surface layers of 19 reservoirs during the summer season of 2010. MCs were detected in 18 reservoirs and 83 % of samples, with median and maximal concentration being 1.5 and 18.6 μg/L, respectively. The high frequency of MC occurrence coincided with prevalence of cyanobacterium Microcystis sp., which was detected in 87 % samples, followed by Dolichospermum (Anabaena) sp. observed in 33 % samples. CYN was detected by ELISA only in one sample at a concentration of 1.2 μg/L. STXs presence was indicated for the first time in Czech water reservoirs when the toxins were found at low concentrations (0.03-0.04 μg/L) in two samples (7 %) collected from two different reservoirs, where STXs co-occurred with MCs and eventually also with CYN. In both STX-positive samples, the phytoplankton community was dominated by Microcystis sp., but Dolichospermum sp. and/or Aphanizomenon sp. were also present as putative producers of STX and/or CYN. Cyanotoxins commonly occurred in Czech water reservoirs, and MCs frequently at concentrations possibly associated with human health risks. MCs were the most prevalent and abundant cyanotoxins, but also other cyanotoxins were detected, though sporadically. Further research and regulatory monitoring of cyanotoxins other than MCs is therefore required.
- MeSH
- alkaloidy MeSH
- Anabaena izolace a purifikace MeSH
- Aphanizomenon izolace a purifikace MeSH
- bakteriální toxiny analýza MeSH
- ELISA MeSH
- fytoplankton izolace a purifikace MeSH
- Microcystis izolace a purifikace MeSH
- mikrobiologie vody * MeSH
- mikrocystiny analýza MeSH
- monitorování životního prostředí metody statistika a číselné údaje MeSH
- mořské toxiny analýza MeSH
- neurotoxiny analýza MeSH
- saxitoxin analýza MeSH
- sinice izolace a purifikace MeSH
- sladká voda chemie mikrobiologie MeSH
- toxiny kmene Cyanobacteria MeSH
- uracil analogy a deriváty analýza MeSH
- zásobování vodou analýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
- Názvy látek
- alkaloidy MeSH
- bakteriální toxiny MeSH
- cylindrospermopsin MeSH Prohlížeč
- microcystin MeSH Prohlížeč
- mikrocystiny MeSH
- mořské toxiny MeSH
- neurotoxiny MeSH
- saxitoxin MeSH
- toxiny kmene Cyanobacteria MeSH
- uracil MeSH
A chemo-organotrophic, aerobic, facultatively anaerobic, non-motile strain, MWH-C5(T), isolated from the water column of the oligomesotrophic Lake Mondsee (Austria), was characterized phenotypically, phylogenetically and chemotaxonomically. The predominant fatty acids of the strain were C(16 : 1)omega7c/omega6c, C(16 : 0), C(12 : 1) and C(8 : 0)-3OH, the major quinone was ubiquinone Q-8 and the G+C content of the DNA of the strain was 55.5 mol%. 16S rRNA gene similarity to the closest related type strains was 96.6 % (Curvibacter delicatus LMG 4328(T)) and 95.7 % (Rhodoferax fermentans FR3(T)). Phylogenetic analysis of 16S rRNA gene sequences revealed the affiliation of the strain with the family Comamonadaceae (Betaproteobacteria); however, the phylogenetic position of the strain did not support an affiliation to any previously described genus within this family. A family-wide comparison of traits revealed that the strain possesses a unique combination of DNA G+C content, major fatty acids and major 3-hydroxy fatty acid. Furthermore, the strain differs in several traits from the closest related genera. Based on the phylogeny of the strain and differences from closely related genera, we propose to establish the new genus and species Limnohabitans curvus gen. nov., sp. nov. to accommodate this strain. The type strain of Limnohabitans curvus is MWH-C5(T) (=DSM 21645(T) =CCUG 56720(T)). The type strain is closely related to a large number of uncultured bacteria detected by cultivation-independent methods in various freshwater systems.
- MeSH
- aminokyseliny analýza MeSH
- Betaproteobacteria klasifikace genetika izolace a purifikace metabolismus MeSH
- elektronová mikroskopie MeSH
- fenotyp MeSH
- fylogeneze MeSH
- fytoplankton klasifikace genetika izolace a purifikace metabolismus MeSH
- mikrobiologie vody * MeSH
- molekulární sekvence - údaje MeSH
- monosacharidy analýza MeSH
- sacharosa analýza MeSH
- sladká voda mikrobiologie MeSH
- teplota MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- aminokyseliny MeSH
- monosacharidy MeSH
- sacharosa MeSH
