Algal Culture Collections Research Articles

Characterization of UV-absorbing Mycosporine-like Amino Acids in Freshwater Cyanobacterium Nostoc calcicola

Mycosporine-like amino acids (MAAs) are gaining attention for their UV photoprotective properties and potential applications in biomedical fields, cosmetics, and toiletries. In this study, Nostoc calcicola a genus of cyanobacteria distributed in freshwater were tested for MAA production. This organism was provided by the Freshwater Algae Culture Collection of the Institute of Hydrobiology, the Chinese Academy of Sciences. It was isolated and cultured in the laboratory, in 500 ml glass flasks containing 300 ml of liquid medium BG11 treated on UV-B light 0.1 Wm–2. At different time, cultures were exposed to UV-B light at intensity 0.1 W. m-1 to determine the Maximum PSII photochemical (Fv/Fm). MAAs were extracted using 100% HPLC grade methanol and separated through high-performance liquid chromatography and liquid chromatography/mass spectrometry. Based on liquid chromatography/mass spectrometry analysis, one MAA compound was identified as porphyra. Thus, UV-B treatment of Nostoc calcicola significantly enhanced the production of UV-absorbing mycosporine-like amino acids (MAAs). The content of porphyra could reach up to 8.5 mg/g dry weight in Nostoc calcicola under UV-B treatments for 2 days. The present cyanobacteria could be used for biotechnology research and the UV-absorbing compound porphyra may be of great value in the development of novel sunscreens.

Exploring cyanobacteria seed resources and corresponding gas-vesicle-biosynthetic elements for producing ultrasound molecular imaging probes

Use of gas vesicles (GVs) as biosynthetic ultrasound molecular imaging (UMI) probes has become a hot topic of research in recent years owing to their advantages of high stability, low risk of toxicity, genetic engineering characterization, easy post-modification, and drug-loading potential. Exploration of natural GV biosynthetic resources and their corresponding biosynthetic elements for various ultrasonic diagnosis and treatment needs to be developed in this field. In this study, we utilized the sequenced cyanobacteria resources preserved in the Freshwater Algae Culture Collection at the Institute of Hydrobiology (FACHB) to screen seed cells and corresponding synthetic elements for biosynthesis of UMI probes. GV operons from the genomes of 158 strains of cyanobacteria were analyzed to identify their natural GV biosynthetic elements. Based on the ultrasound screening method (VINNO D860LAB, 2D transducer X6-16L, 50 % output power mode, MI: 1.116), 57 seed resources with biosynthetic UMI probe potential from 10 genera were selected from 158 strains of cyanobacteria, corresponding to 28 types of effective biosynthetic elements. These results provide a theoretical basis for future mass production of customized GVs in chassis cells and their application in UMI.

Description of Gloeomargarita ahousahtiae sp. nov. (Gloeomargaritales), a thermophilic cyanobacterium with intracellular carbonate inclusions

ABSTRACT A unicellular cyanobacterium, strain VI4D9, was isolated from thermophilic microbial mats thriving in a hot spring of the Ahousaht territory of Vancouver Island, Canada, and characterized using optical and electron microscopy, genome sequencing and cultivation approaches. The cells were elongated rods (5.1 µm in length and 1.2 µm in width, on average). Their UV visible absorption spectra revealed that they contain chlorophyll a, phycocyanin and carotenoids. Transmission electron microscopy showed the presence of thylakoids concentrated on one side of the cells. The strain grew within a temperature range of 37–50°C, with an optimum growth at 45°C. Its genome had a size of 3 049 282 bp and a DNA G + C content of 51.8 mol%. The cells contained numerous intracellular spherical granules easily visible under scanning electron microscopy. Energy dispersive X-ray spectroscopy revealed that these granules were made of Ca-, Ba- and Sr-containing carbonates. A phylogenetic 16S rRNA gene tree robustly placed this strain as sister to several environmental sequences and the described species Gloeomargarita lithophora, also characterized by the possession of intracellular carbonate inclusions. We consider strain VI4D9 to represent a new Gloeomargarita species based on its marked phenotypic differences with G. lithophora, notably, its thermophilic nature and different thylakoid organization, therefore we propose the name Gloeomargarita ahousahtiae sp. nov. The type strain is VI4D9 (Culture Collection of Algae and Protozoa strain 1472/1; Laboratorio de Algas Continentales Mexico strain LAC 140). Gloeomargarita ahousahtiae is the second species described within the recently discovered order Gloeomargaritales.

Outcome of Microalgae Biomass Application on Seed Germination and Hormonal Activity in Winter Wheat Leaves

The present work aimed to test selected microalgae strains from the Mosonmagyaróvár Algae Culture Collection (MACC) on germination ability and certain physiological processes in winter wheat (Triticum aestivum L.) plants. Germination tests showed substantial differences between the strains, meaning that certain strains (such as MACC-430, MACC-612, MACC-922) improved the germination processes while others performed worse (MACC-438, MACC-755) than the control in a concentration-dependent manner. The germination index of seeds treated with MACC-430 @ 1 g L−1 concentrations was 87, while that of the control was 45. The mungbean rooting bioassay proves that microalgae biomass may exhibit auxin-like activity, especially in strain MACC-612 (Nostoc sp.), which was characterized by the highest endogenous level of plant growth regulator indole-3-acetic-acid among the selected strains. Foliar spray on the leaves of developed plants did not significantly alter the photosynthetic processes, but it influenced the secondary metabolite composition. After the application of microalgae biomass, there were also changes in plant hormones, including salicylic acid, abscisic acid, and jasmonic acid-leucine/isoleucine conjugate compositions, which play a role in plant stress signaling in plants. A decrease in indole-3-acetic acid was also observed in the Mv Nádor cultivar. These results suggest that the application of certain microalgae strains can be used effectively to improve the germination of wheat seeds, and as a foliar spray, they may also modify the acclimation processes in a genotype-dependent way.

Cataloguing microalgae and Cyanobacteria strains from the Mosonmagyaróvár Algal Culture Collection with in vitro antagonistic activity against phytopathogenic fungi and oomycetes

Cataloguing microalgae and Cyanobacteria strains from the Mosonmagyaróvár Algal Culture Collection with in vitro antagonistic activity against phytopathogenic fungi and oomycetes

Spirulina platensis Suppressed iNOS and Proinflammatory Cytokines in Lipopolysaccharide-Induced BV2 Microglia.

The disease burden of neurodegenerative diseases is on the rise due to the aging population, and neuroinflammation is one of the underlying causes. Spirulina platensis is a well-known superfood with numerous reported bioactivities. However, the effect of S. platensis Universiti Malaya Algae Culture Collection 159 (UMACC 159) (a strain isolated from Israel) on proinflammatory mediators and cytokines remains unknown. In this study, we aimed to determine the anti-neuroinflammatory activity of S. platensis extracts and identify the potential bioactive compounds. S. platensis extracts (hexane, ethyl acetate, ethanol, and aqueous) were screened for phytochemical content and antioxidant activity. Ethanol extract was studied for its effect on proinflammatory mediators and cytokines in lipopolysaccharide (LPS)-induced BV2 microglia. The potential bioactive compounds were identified using liquid chromatography-mass spectrometric (LC-MS) analysis. Ethanol extract had the highest flavonoid content and antioxidant and nitric oxide (NO) inhibitory activity. Ethanol extract completely inhibited the production of NO via the downregulation of inducible NO synthase (iNOS) and significantly reduced the production of tumor necrosis factor (TNF)-α and interleukin (IL)-6. Emmotin A, palmitic amide, and 1-monopalmitin, which might play an important role in cell signaling, have been identified. In conclusion, S. platensis ethanol extract inhibited neuroinflammation through the downregulation of NO, TNF-α and IL-6. This preliminary study provided insight into compound(s) isolation, which could contribute to the development of precision nutrition for disease management.

Abundant Species Diversity and Essential Functions of Bacterial Communities Associated with Dinoflagellates as Revealed from Metabarcoding Sequencing for Laboratory-Raised Clonal Cultures.

Interactions between algae and bacteria represent an important inter-organism association in aquatic environments, which often have cascading bottom-up influences on ecosystem-scale processes. Despite the increasing recognition of linkages between bacterioplankton and dynamics of dinoflagellate blooms in the field, knowledge about the forms and functions of dinoflagellate-bacteria associations remains elusive, mainly due to the ephemeral and variable conditions in the field. In this study, we characterized the bacterial community associated with laboratory cultures of 144 harmful algal strains, including 130 dinoflagellates (covering all major taxonomic orders of dinoflagellates) and 14 non-dinoflagellates, via high-throughput sequencing for 16S rRNA gene amplicons. A total of 4577 features belonging to bacteria kingdom comprising of 24 phyla, 55 classes, 134 orders, 273 families, 716 genera, and 1104 species were recovered from the algal culture collection, and 3 phyla (Proteobacteria, Bacteroidetes, and Firmicutes) were universally present in all the culture samples. Bacterial communities in dinoflagellates cultures exhibited remarkable conservation across different algal strains, which were dominated by a relatively small number of taxa, most notably the γ-proteobacteria Methylophaga, Marinobacter and Alteromonas. Although the bacterial community composition between dinoflagellates and non-dinoflagellate groups did not show significant difference in general, dinoflagellates harbored a large number of unique features (up to 3811) with relatively low individual abundance and enriched in the potential methylotrophs Methylophaga. While the bacterial assemblages associated with thecate and athecate dinoflagellates displayed no general difference in species composition and functional groups, athecate dinoflagellates appeared to accommodate more aerobic cellulolytic members of Actinobacteria, implying a more possible reliance on cellulose utilization as energy source. The extensive co-occurrence discovered here implied that the relationships between these algal species and the bacterial consortia could be viewed as either bilaterally beneficial (i.e., mutualism) or unilaterally beneficial at least to one party but virtually harmless to the other party (i.e., commensalism), whereas both scenarios support a long-term and stable co-existence rather than an exclusion of one or the other. Our results demonstrated that dinoflagellates-associated bacterial communities were similar in composition, with enrichment of potential uncultured methylotrophs to one-carbon compounds. This work enriches the knowledge about the fundamental functions of bacteria consortia associated with the phycospheres of dinoflagellates and other HABs-forming microalgae.

Cocconeis czarneckii sp. nov. (Bacillariophyta): a new diatom species from Lake Okoboji (Iowa, USA), based on the strain UTEX FD23

ABSTRACT The nucleotide sequences (18S and rbcL) of the freshwater diatom strain UTEX FD23 were revisited and its morphology studied for the first time. This strain is maintained at the UTEX Culture Collection of Algae, where it is referred to as Cocconeis placentula var. lineata. The sequences of this strain had been deposited in NCBI and used in more than 30 studies mostly under the name C. placentula, but also C. placentula var. lineata. We describe this species as new, based on sequence data and morphology (LM and SEM), which did not correspond to the epitypes of C. placentula var. placentula, C. lineata or any other described member of the C. placentula group. According to genetic distances for 18SV4, this new species is closest to C. placentula sensu stricto (5.8%), and has a distance of 7.9% to C. lineata. For rbcL, C. czarneckii is closest to the recently described C. coreana (2.6%–2.8%), it has a distance of 4.1% to C. lineata, and of 4.2% to C. placentula. Morphologically, C. czarneckii shares similarities with C. sijunghoensis, C. amerieuglypta, C. klamathensis and C. grovei, which differ by valve size and outline, numbers and pattern of submarginal areolae, and ultrastructural details of the valvocopula of the raphe valve. Our study, integrating available nucleotide sequences with a detailed morphological characterization of the strain UTEX FD23, added to our understanding of the heterogeneity of the C. placentula group, and will benefit the scientific community interested in this strain (e.g. for taxonomy, molecular phylogenetics and eDNA metabarcoding).

Morphological and phylogenetic relations of members of the genus Coelastrella (Scenedesmaceae, Chlorophyta) from the Ural and Khentii Mountains (Russia, Mongolia)

We describe the morphological features and the phylogenetic relationships of five morphologically similar strains belonging to the genus Coelastrella, which live in different ecological and geographical conditions of terrestrial ecosystems: in the Ural Mountains (Polar, Subpolar, and Northern Urals of Russia) and the Khentii Mountains (Russia and Mongolia). We analysed algal strains stored in the Culture Collection of Algae of the Institute of Biology, Syktyvkar, Russia (SYKOA Ch-045-09, SYKOA Ch-047-11, SYKOA Ch-072-17) and the Culture Collection of Algae at Herbarium of the Siberian Institute of Plant Physiology and Biochemistry, Irkutsk, Russia (IRK-A 2, IRK-A 173). By light microscopy, all samples were assigned to Coelastrella terrestris. However, the phylogenetic analyses based on the nucleotide sequences of 18S rDNA and ITS1-ITS2 showed that only one strain belongs to C. terrestris (IRK-A 173). Other samples were closer to C. oocystiformis (SYKOA Ch-045-09; IRK-A 2) and C. aeroterrestrica (SYKOA Ch-047-11). The strain SYKOA Ch-072-17 is probably a new species for the genus. These results confirmed the high phenotypic variability and the hidden diversity among the members of this green algal group.

Cell size influences inorganic carbon acquisition in artificially selected phytoplankton.

Cell size influences the rate at which phytoplankton assimilate dissolved inorganic carbon (DIC), but it is unclear whether volume-specific carbon uptake should be greater in smaller or larger cells. On the one hand, Fick's Law predicts smaller cells to have a superior diffusive CO2 supply. On the other, larger cells may have greater scope to invest metabolic energy to upregulate active transport per unit area through CO2 -concentrating mechanisms (CCMs). Previous studies have focused on among-species comparisons, which complicates disentangling the role of cell size from other covarying traits. In this study, we investigated the DIC assimilation of the green alga Dunaliella tertiolecta after using artificial selection to evolve a 9.3-fold difference in cell volume. We compared CO2 affinity, external carbonic anhydrase (CAext ), isotopic signatures (δ13 C) and growth among size-selected lineages. Evolving cells to larger sizes led to an upregulation of CCMs that improved the DIC uptake of this species, with higher CO2 affinity, higher CAext and higher δ13 C. Larger cells also achieved faster growth and higher maximum biovolume densities. We showed that evolutionary shifts in cell size can alter the efficiency of DIC uptake systems to influence the fitness of a phytoplankton species.

Integration of bioelectricity generation from algal biophotovoltaic (BPV) devices with remediation of palm oil mill effluent (POME) as substrate for algal growth

The exploitation of renewable energy sources for delivering carbon neutral or carbon negative solutions has to be achieved through strategies involving the removal of CO2 from the atmosphere. Agro-industries like palm oil processing are important sources of energy but are also generators of large volumes of wastewater, causing pollution problems. Bioremediation of these effluents utilizing microalgae has shown promising results. In the present study, we developed an algal-biophotovoltaic device to generate direct bioelectricity from photosynthesis while using palm oil mill effluent (POME) as substrate for microalgal growth. Nine microalgal strains from the University of Malaya Algae Culture Collection (UMACC) were cultured using POME in four different concentrations (50%, 25%, 10%, and 5%) for 12 days. Chlorella vulgaris Beijerinck UMACC 051 showed the highest specific growth rate (1.32 d−1) and Chlorella UMACC 301 showed high photosynthetic performance (Alpha = 0.88) when grown in 5% POME–BBM medium. Three selected microalgal strains were grown in the control medium (Bold’s Basal Medium) and 5% POME–BBM medium in an annular biophotovoltaic device. The maximum power density (0.45 mW m−2) obtained from Chlorella UMACC 313 in the POME–BBM medium, was 15% higher than the power density generated when the microalgal cells were grown in the control medium (0.38 mW m−2). When Chlorella UMACC 313 was cultured in a 4L round integrated fuel cell-photobioreactor prototype device, the maximum power density obtained was 0.28 mW m−2. The reductions in NO3-N, o-PO43−, NH3-N and COD were 54.92%, 29.41%, 80.75 and 60.09% respectively. A final biomass of 810 mg L−1 was obtained after 12 days’ growth and the CO2 fixation rate was 76.82 mgCO2 L−1 d−1. This BPV system represents a multi-functional system that generates low power density while providing wastewater bioremediation and carbon removal. This has potential as a sustainable environment-friendly carbon-neutral or carbon-reducing energy generation system.

Cryopreservation to sustain long term maintenance of algae and protozoa in the culture collection of algae and protozoa (CCAP)

Cryopreservation to sustain long term maintenance of algae and protozoa in the culture collection of algae and protozoa (CCAP)

Patent depositing of algal strains

ABSTRACT Algae and protozoa underpin biological productivity from the poles to the equator, produce most of the world’s oxygen and a myriad of valuable commodities such as pigments, oils, antioxidants and proteins. Algae are the subject of many thousands of patent applications in varied fields from bioremediation to nutraceuticals. The patenting of microorganisms including algae was made easier and more secure with the signing of the Budapest Treaty and the creation of International Depositary Authorities, such as the Culture Collection of Algae and Protozoa (CCAP), which is a Biological Resource Centre and is a trusted global leader in the provision of algal and protozoan cultures, knowledge and associated services. There are challenges ahead in incorporating Intellectual Property laws with Access and Benefit Sharing regulations such as the Nagoya Protocol but tools are being developed to enable progress.

Algal culture collections in the omics age

Algal culture collections act as specified resource centres and international depositories for cyanobacteria and eukaryotic algae. They underpin and actively contribute to research, teaching and bi...

Identifying drivers of microbial community composition associated with aquatic primary producers: metagenomic analysis of cyanobacterial cultures

The energy derived from aquatic primary production is fundamental to driving Earth’s life support systems – but they don’t achieve all this by themselves. Heterotrophic bacteria found in the photic zones of aquatic environments have a fundamental role in this too. Our group’s interest is in understanding how heterotrophs help autotrophs: who in these communities are important, and how and why they are important. Answering this is important in both natural and manmade environments so we can model these environments, and as appropriate, manipulate them, such as applying designer microbiomes to aid industrialisation of algal cultivation. Metagenomic analysis of 31 marine and freshwater cyanobacterial cultures from the Culture Collection of Algae & Protozoa resulted in assembly of >400 bacterial metagenomes (MAGs) with ca. 14 unique MAGs per culture. Community composition was clearly partitioned by salinity as a driver but collectively niche accounted for most community taxonomic variation. No universal core microbiome was identified, but taxonomic composition of marine cultures bore notable similarities to marine eukaryotic algal communities and to a natural cyanobacterial mat community found next to a northern Chilean geyser. Stable taxonomic associations imply that these taxa may have functional importance to their algal host. Functional analysis of the MAGs is underway and we will test whether the relative taxonomic variability contrasts with low functional variation between communities. If true, this implies that primary producers drive community assembly in a functionally predictable way, and that function, not taxonomy, is the more important parameter to understand.

Exploring the distinctiveness of biomass and biomolecules from limnic microalgae of unexplored waters of Noyyal River, Western Ghats, for exploitation.

Oleaginous microalgae with high biomass productivity, lipid content, and lipid productivity are desirable for sustainable biofuel production. Rapid and accurate quantification of lipid content facilitates the identification of promising microalgae candidates. In the present study, 23 freshwater microalgae species from river Noyyal were isolated and identified based on their morphological and molecular (18S rRNA) features and recorded as Karunya Algae Culture Collection (KACC). Their biomass and lipid content were characterized and screened using FT-IR, Nile red staining, and gravimetric method. Results generated from FT-IR spectra differentiated KACC microalgae based on their biochemical contents with Scenedesmus rubescens KACC 2 and Chlorococcum sp. KACC 13 possessed high total protein and lipid content, respectively. Nile red fluorescence at 530/575nm showed the yellow fluorescence under a fluorescent microscope giving the evidence of high neutral lipids in 10 KACC microalgae isolates. Total lipid content showed prominent variation between the KACC isolates and found in the range of 4 to 32% of DW. Lipid productivity and biomass productivity showed a similar pattern among KACC strains. Thus, our findings serve as a baseline data on the bioprospecting potential of KACC isolates from river Noyyal, an unexplored area of Western Ghats.

ОЧИЩЕННЯ КУЛЬТУР МІКРОВОДОРОСТЕЙ КОЛЕКЦІЇ ACKU ВІД ГРИБНИХ КОНТАМІНАНТІВ

The work is focused to the selection of the best purification methods of microalgae strains from ACKU collection (Algae Culture Collection of Kyiv University) from contamination by microscopic fungi. The screening of microalgae culture collection ACKU (Algae Culture Collection of Kyiv University) is deal. Contamination of some microalgae strains by fungi of Cladosporium Link, Alternaria Nees, and Monilia Bonord genera was detected. The following strains were selected for the experiment: ACKU 139-02 (Klebsormidium flaccidum (Kütz.) PC Silva, Mattox et Blackwell), ACKU 293-04 (Acutodesmus obliquus (Turpin) P. Tsarenko), ACKU 364-04 (cf. Chlorosarcinopsis dissociata Herndon), ACKU 599-06 (Klebsormidium nitens Menegh. in Kützing), ACKU 600-06 (Klebsormidium flaccidum (Kütz.) PC Silva, Mattox et Blackwell) и ACKU 1056 (Desmodesmus abundans (Kirchn.) E. Hegew.). The effect of carbendazim (Methylbenzimidazol-2-ylcarbamate), Antibiotic Antimycotic Solution (penicillin – 10,000 IU, streptomycin – 10 mg, amphotericin B – 25 μg) and Nuosept BMc 422 on fungi-contaminants of green algal culture strains with different morphological structure (coccoid and filamentous) was studied. Experimental concentrations of substances: carbendazim – 0.005%, Antibiotic Antimycotic Solution – 1%, Nuosept BMc 422 – 0.05% and 0.2%. Was shown that Antibiotic-Antimycotic Solution and Nuosept BMc-422 at the selected concentrations were not effective for purifying of green algae strains from significant contamination by microscopic fungi. It was found that the carbendazim solution is effective in the purification of cocoid green algae strains from contamination by microscopic fungi Cladosporium cladosporioides (Fresen.) G.A. de Vries). As a result, an axenic culture was obtained for the ACKU strain No.293-04 (A. obliquus).

Biosilica slab photonic crystals as an alternative to cleanroom nanofabrication?

Photonics, the manipulation of light at nanoscale, is a key enabling technology with impact in health and energy applications, among others. In most cases photonics still relies on materials and fabrication methods inherited from other disciplines, usually requiring expensive, time-consuming and environmentally-unfriendly processes. Recent experiments demonstrated that advanced photonic materials, as complex as those known as 2.5 dimensional slab photonic crystals, also occur naturally in diatoms. These microscopic algae precipitate silicic acid from water to produce silicon dioxide membranes, relying on intracellular biomineralization mechanisms. Addressing some important aspects for the potential industrial utilization of these structures, we here propose that optical materials produced by the diatoms could serve as cost-effective and environmentally friendly alternatives to cleanroom nanofabrication. We demonstrate that photonic materials grown by the diatom species Coscinodiscus granii can be separated based on its hydrokinetic characteristics. We further show that the photonic membranes present low defect rates of ca. 1/100 unit cells and that variation in pore diameter, as observed between individual membranes, can affect the photonic properties at large, but only marginally at low refractive index contrast. Finally, we list algal culture collections operating worldwide, thus providing a global network for live diatoms and diatom materials. We discuss the feasibility and bottlenecks related to scaled-up growth for direct utilization of photonic materials from diatoms.

Non-pollen palynomorphs notes: 3. Phototrophic loricate euglenoids in paleoecology and the effect of acetolysis on Trachelomonas loricae

Algal palynomorphs are useful indicators of freshwater environments in the past and present, allowing reconstruction of such environmental characteristics as former pH, trophic stage, temperature and salinity. However, the using of algal palynomorphs in paleoecology is restricted by their resistance to natural degradation and acetolysis treatment. In this study, we evaluate the usefulness of the loricate euglenophyte genera Trachelomonas and Strombomonas as paleoecological indicators. In order to evaluate their resistance to degradation, loricae morphology of four Trachelomonas species from the Culture Collection of Algae at Göttingen University (SAG) were studied with and without acetolysis treatment. The experiment demonstrates a strong dissolution under acetolysis of the three species T. hispida, T. lefévrei, T. zorensis and a reduction in the loricae length by T. similis. In the Holocene records, Trachelomonas can be found in non-acetolyzed samples, occurring together with other eutrophication indicators such as cyanobacteria and ciliate Codonella cratera. A review of recent algological literature supports Trachelomonas being a good indicator of organic pollution.

Molecular taxonomic evaluation of Anabaena and Nostoc strains from the Mosonmagyaróvár Algal Culture Collection

The taxonomy of genera Anabaena and Nostoc is very controversial. They are typically paraphyletic within phylogenetic trees and show similar morphological characters. The present study aimed to determine the taxonomic relationships among Anabaena and Nostoc strains of the Mosonmagyaróvár Algal Culture Collection (MACC) using 16S rRNA and rbcLX gene sequences. We concluded on the basis of the number of unsuccessful amplifications that more of the examined MACC Nostoc cultures are axenic than the Anabaena cultures. In agreement with previous studies we noticed that the applied phylogenetic algorithms gave congruent results in phylogenetic analyses. However, the genus Nostoc clearly was found not monophyletic in the present study and this finding differed from many of the previous studies. Molecular results contradicted the previous morphology-based classification of some MACC cyanobacteria strains, therefore polyphasic taxonomic approaches are required for the reliable identification of cyanobacterial species. Some strains seemed to be identical based on the alignment of 16S rRNA or rbcLX sequences.