The effect of temperature, light and nutrient composition on morphological traits was determined in seven nostocacean cyanobacteria
(Anabaena planctonica, A. sphaerica
var.
conoidea, A. spiroides, ...Aphanizomenon gracile, Nostoc
sp.,
Scytonema
sp., and
Tolypothrix
sp.). Their morphological variability was high but only some of the features showed changes reflecting varied growth conditions. The frequency of heterocyst occurrence decreased with increasing nitrogen concentration. Within the range studied, the effect of temperature on heterocyst frequency of
Tolypothrix
sp. and planktonic
Anabaena
strains could be fitted by a normal curve with a clear optimum while linear correlation was found in
Aphanizomenon gracile
. T-and S-type branching was observed in both
Scytonema
sp. and
Tolypothrix
sp. strains. T-type branching was found to be markedly dependent on nitrogen concentration. The abundance of necridic cells of
Tolypothrix
sp. increased linearly with temperature and light intensity. Regularity of trichome coiling of
A. spiroides
depended on culture medium, suggesting that nutrient composition may be the main controlling factor. In contrast, the effect of the experimental conditions on the dimensions of vegetative cells and heterocysts was weak. Their variability was markedly higher within each experimental treatment than between treatments.
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An abstract of a study by Klimešová et al on the diversity and taxonomy of freshwater and subaerial members of ulvales/ulotrichales is presented. In this research we gather strains from foreign algal ...culture collections and also isolate strains from natural localities within the Czech Republic, Sardinia and particular type localities. Our main goal is to discover the real diversity of the freshwater and subaerial members of Ulvales/Ulotrichales and to elucidate the true relationships in some problematic genera (Dilabifilum, Pseudendoclonium).
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The potential for N(2) fixation by heterocystous cyanobacteria isolated from soils of different geographical areas was determined as nitrogenase activity (NA) using the acetylene reduction assay. ...Morphology of cyanobacteria had the largest influence on NA determined under light conditions. NA was generally higher in species lacking thick slime sheaths. The highest value (1446 nmol/h C(2)H(4) per g fresh biomass) was found in the strain of branched cyanobacterium Hassalia (A Has1) from the polar region. A quadratic relationship between NA and biomass was detected in the Tolypothrix group under light conditions. The decline of NA in dark relative to light conditions ranged from 37 to 100 % and differed among strains from distinct geographical areas. Unlike the NA of temperate and tropical strains, whose decline in dark relative to light was 24 and 17 %, respectively, the NA of polar strains declined to 1 % in the dark. This difference was explained by adaptation to different light conditions in temperate, tropical, and polar habitats. NA was not related to the frequency of heterocysts in strains of the colony-forming cyanobacterium Nostoc. Colony morphology and life cycle are therefore more important for NA then heterocyst frequency. NA values probably reflect the environmental conditions where the cyanobacterium was isolated and the physiological and morphological state of the strain.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Algal communities were investigated in two contrasting chronosequences established on reclaimed spoils in the west Bohemian brown coal mining district near Sokolov (Czech Republic) and in the ...Lusatian lignite mining district near Cottbus (Germany). The Sokolov chronosequence was characterized by tertiary cypric clay substrate, afforestation with Alnus glutinosa (L.) Gaertn., and high pH of deposited spoil material, Cottbus chronosequence by tertiary carboniferous and pyritic sand of extremely low pH ameliorated by fly ash, and afforestation with Pinus sylvestris L. and P. nigra Arnold. A total of 122 species of algae was found in both areas. Although the same species number (80) was identified from Sokolov and Cottbus, both proportion of individual algal groups and species composition were different. Green algae prevailed in both areas, but in Sokolov cyanobacteria and diatoms were also quite diverse, and in younger sites they were also abundant. Total abundance of algae ranged mostly between 104–107 cells/g dry soil, and was one order higher in Cottbus than in Sokolov. Species number was high in young sites, decreased with increasing age, and was the lowest in control forests. In Sokolov, the highest abundance was recorded in the youngest alder plantation. In Cottbus, sludge and compost fertilization used in the youngest pine plantations resulted in rapid formation of visible algal crusts dominated by Klebsormidium crenulatum (Kütz) Lokhorst.
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Frequency of heterocytes and nitrogenase activity (NA) under light and dark cultivation conditions was determined in 12 cyanobacterial strains isolated from various soil habitats. In spite of a high ...variability, significant differences in NA among the strains were found in response of light and dark cultivation. Relatively high NA (9.9-15.3 micromol/h C2H4 per g fresh mass) under light conditions and basal NA after 12 h of dark cultivation were detected in Anabaena, Nodularia, Tolypothrix, and 1 of Cylindrospermum strains. On the other hand, significantly lower NA (0.76-5.4 micromol/h C2H4 per g fresh mass) was found under light conditions in Trichormus, Nostoc and another Cylindrospermum strain; the activity completely disappeared after 12 h of dark cultivation. NA values were not directly related to the frequency of the heterocytes. The total NA of cyanobacterial colony was found to be probably independent of the number and/or position of heterocytes. Remarkable differences in NA between strains isolated from cultivated fields and strains originating from natural or non-cultivated soils were found.
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A. Lukešová, J.R. Johansen, M.P. Martin and D.A. Casamatta. 2009. Aulosira bohemensis sp. nov.: further phylogenetic uncertainty at the base of the Nostocales (Cyanobacteria). Phycologia 48: 118-129. ...DOI: 10.2216/08-56.1
Aulosira bohemensis sp. nov. was isolated from a wet meadow soil in South Bohemia, Czech Republic. It shares all the features of the majority of other Aulosira species, including isopolar development with intercalary heterocytes and apoheterocytic akinete development. It differs from all other species through the production of hormogonia perpendicular to the trichome axis following akinete germination. Morphologically the genus Aulosira appears closest to Nodularia, however, phylogenetic placement of A. bohemensis based on 16S rRNA was distant from that taxon. Aulosira falls within the Nostocaceae, with possible sister taxa in Trichormus, Mojavia and Nostoc. Despite the variety of phylogenetic analyses performed, we were unable to obtain bootstrap support for its position in any tree, and its correct phylogenetic position within the Nostocaceae remains unresolved.
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Microalgae are one of the most biologically important elements of worldwide ecology and could be the source of diverse new products and medicines. COBRA (The COnservation of a vital european ...scientific and Biotechnological Resource: microAlgae and cyanobacteria) is the acronym for a
European Union, RTD Infrastructures project (Contract No. QLRI-CT-2001-01645). This project is in the process of developing a European Biological Resource Centre based on existing algal culture collections. The COBRA project's central aim is to apply cryopreservation methodologies to microalgae
and cyanobacteria, organisms that, to date, have proved difficult to conserve using cryogenic methods. In addition, molecular and biochemical stability tests have been developed to ensure that the equivalent strains of microorganisms supplied by the culture collections give high quality and
consistent performance. Fundamental and applied knowledge of stress physiology form an essential component of the project and this is being employed to assist the optimisation of methods for preserving a wide range of algal diversity. COBRA's "Resource Centre" utilises Information Technologies
(IT) and Knowledge Management practices to assist project coordination, management and information dissemination and facilitate the generation of new knowledge pertaining to algal conservation. This review of the COBRA project will give a summary of current methodologies for cryopreservation
of microalgae and procedures adopted within the COBRA project to enhance preservation techniques for this diverse group of organisms.
1 Department of Botany, Stockholm University, S-10691 Stockholm, Sweden
2 Department of Botany, Faculty of Biological Sciences, University of South Bohemia, eské Bud jovice, Czech Republic
3 ...Institute of Physical Biology, University of South Bohemia, Nové Hrady, Czech Republic
4 Institute of Microbiology, Department of Autotrophic Microorganisms, Academy of Sciences of the Czech Rrepublic, Opatovick Ml n, T ebo , Czech Republic
5 Institute of Ecosystem Study, National Research Council of Italy, via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy
6 PhD School in Science for Conservation of the Cultural Heritage, University of Florence, Italy
7 Institute of Soil Biology, Biology Centre AS CR, v. v. i., Na Sádkách 7, 37005 eské Bud jovice, Czech Republic
8 PhD School in Polar Science, University of Siena, Italy
Correspondence Stefano Ventura stefano.ventura{at}ise.cnr.it
Many cyanobacteria commonly identified as belonging to the genus Nostoc are well-known cyanobionts (symbionts) of a wide variety of plants and fungi. They form symbioses with bryophytes, pteridophytes, gymnosperms and angiosperms that are considerably different in the type of reciprocal interaction between the host and the cyanobiont. The phylogenetic and taxonomic relationships among cyanobionts isolated from different hosts and Nostoc strains isolated from free-living conditions are still not well understood. We compared phylogeny and morphology of symbiotic cyanobacteria originating from different host plants (genera Gunnera , Azolla , Cycas , Dioon , Encephalartos , Macrozamia and Anthoceros ) with free-living Nostoc isolates originating from different habitats. After preliminary clustering with ARDRA (amplified rDNA restriction analysis), phylogeny was reconstructed on the basis of 16S rRNA gene sequences and compared with morphological characterization, obtaining several supported clusters. Two main Nostoc clusters harboured almost all cyanobionts of Gunnera , Anthoceros and of several cycads, together with free-living strains of the species Nostoc muscorum , Nostoc calcicola , Nostoc edaphicum , Nostoc ellipsosporum and strains related to Nostoc commune . We suggest that the frequent occurrence of symbiotic strains within these clusters is explained by the intensive hormogonia production that was observed in many of the strains studied. However, no evidence for discrimination between symbiotic and free-living strains, either by molecular or morphological approaches, could be found. Sequences of Azolla cyanobiont filaments, taken directly from leaf cavities, clustered tightly with sequences from the planktic cyanobacterium Cylindrospermopsis raciborskii , from the benthic Anabaena cylindrica 133 and from Anabaena oscillarioides HINDAK 1984/43, with high bootstrap values. The phylogenetic analysis showed that two distinct patterns of evolution of symbiotic behaviour might exist for the nostocacean cyanobacteria, one leading to symbioses of Nostoc species with a wide variety of plants, the other leading to the association of a unique cyanobacterial type with the water fern Azolla .
Abbreviations: AKLC, akinete-like cells; ARDRA, amplified rDNA restriction analysis; ITS, internal transcribed spacer; ML, maximum-likelihood; MP, maximum-parsimony; NJ, neighbour-joining
The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequences determined in this study are AM711522 –AM711554.
A supplementary figure showing the ARDRA of symbiotic and free-living cyanobacteria performed on the 16S rRNA gene+ITS region is available with the online version of this paper.
Density and community composition of a wide spectrum of soil organisms (fungi, algae, testate amoebae, nematodes, enchytraeids, lumbricids, oribatid mites, diplopods, terrestrial isopods, ...collembolans and dipteran larvae), direct counts of bacteria, rate of cellulose decomposition and microstructure of upper soil layers were studied in two chronosequences of plots reclaimed from open-cast coal mining near Cottbus (Germany) and near Sokolov (Czech Republic). German plots were characterized by acidic sandy soils and afforested with pine, while the Czech plots possessed alkaline clay soils and were afforested with alder. In both chronosequences, density and species richness in most of investigated groups of soil biota gradually increased with increasing succession age. Typical pioneer species were found in initial stands of both chronosequences. Nevertheless, the initial stands supported poorer assemblages of soil biota in the Cottbus area than did those in the Sokolov area. The Cottbus area was characterized by a moor type of humus and by gradual uniform increase of abundances and species numbers of most studied groups of soil biota. On the contrary, moder type of humus and a more variable pattern of soil biota development during the course of succession were found in the Sokolov area. Slower development of soil biota in initial stages of succession in Cottbus is caused by unfavourable physical and chemical conditions of heap substrates, and by lower input and poor quality of litter in pine plantations.
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The effect of consuming terrestrial algae on the cold tolerance of two Antarctic micro-arthropods was examined. From the results of preferential feeding experiments, seven species of Antarctic ...terrestrial micro-algae were chosen and fed to two common, freeze-avoiding Antarctic micro-arthropods: the springtail Cryptopygus antarcticus (Collembola: Isotomidae), and the mite Alaskozetes antarcticus (Acari: Oribatida). Mites were very selective in their choice of food whereas the springtails were less discriminating. The ice nucleating activity of each species of alga was measured using an ice nucleator spectrometer and a differential scanning calorimeter. Pure cultures of individual species of algae had characteristic supercooling points ranging from ca. -5 to -18 degree C. The effect of eating a particular alga on the supercooling point of individual micro-arthropods cultured at two different temperatures (0 and 10 degree C) was examined. Neither species showed a preference for algae with low ice-nucleating activity and there was no clear correlation between the supercooling point of food material and that of the whole animal. However, feeding on certain algae such as Prasiola crispa, which contained the most active ice nucleators, decreased the cold tolerance of both species of arthropods.
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