Molecular characterization of microcystin-producing cyanobacteria from Romanian fresh waters

Drugă, Bogdan; Welker, Martin; Sesărman, Alina; Hegedüs, Adriana; Coman, Cristian; Sicora, Cosmin; Dragoş, Nicolae

doi:10.1080/09670262.2013.822563

Cited by 4 publications

(3 citation statements)

References 25 publications

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“…This number must be placed in relation to the more than 240 microcystins that have been previously described in microcystin producing cyanobacteria [26]. For example, Microcystis strain CAWBG11 was found to produce 27 different microcystin variants [28], whereas Microcystis strains in other studies [50][51][52] produced less than five microcystins simultaneously. Additionally, a literature summary [28]) has reported a median number of 4-5 microcystins produced simultaneously by cyanobacterial strains.…”

Section: Discussionmentioning

confidence: 99%

High Diversity of Microcystin Chemotypes within a Summer Bloom of the Cyanobacterium Microcystis botrys

Johansson

Legrand

Björnerås

et al. 2019

Toxins

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The fresh-water cyanobacterium Microcystis is known to form blooms world-wide, and is often responsible for the production of microcystins found in lake water. Microcystins are non-ribosomal peptides with toxic effects, e.g. on vertebrates, but their function remains largely unresolved. Moreover, not all strains produce microcystins, and many different microcystin variants have been described. Here we explored the diversity of microcystin variants within Microcystis botrys, a common bloom-former in Sweden. We isolated a total of 130 strains through the duration of a bloom in eutrophic Lake Vomb, and analyzed their microcystin profiles with tandem mass spectrometry (LC-MS/MS). We found that microcystin producing (28.5%) and non-producing (71.5%) M. botrys strains, co-existed throughout the bloom. However, microcystin producing strains were more prevalent towards the end of the sampling period. Overall, 26 unique M. botrys chemotypes were identified, and while some chemotypes re-occurred, others were found only once. The M. botrys chemotypes showed considerable variation both in terms of number of microcystin variants, as well as in what combinations the variants occurred. To our knowledge, this is the first report on microcystin chemotype variation and dynamics in M. botrys. In addition, our study verifies the co-existence of microcystin and non-microcystin producing strains, and we propose that environmental conditions may be implicated in determining their composition. Key Contribution:This study demonstrates that a single bloom of Microcystis botrys consists of strains with different microcystin chemotypes, each producing from zero up to 12 different microcystin variants. We established that microcystin and non-microcystin producing strains co-occur, and that the chemotype composition varies during the bloom.Toxins 2019, 11, 698 2 of 16 bloom-forming cyanobacteria, and that harmful blooms will increase both in frequency and duration, due to direct and indirect effects of changes in hydrological cycling, increased water temperatures, and nutrient loading [4][5][6][7][8][9].In addition to forming dense blooms which can deteriorate water quality per se, many cyanobacterial genera produce secondary metabolites with significant bioactivity and toxicity to aquatic organisms and humans [10][11][12][13][14]. In freshwaters, microcystins are among the most common cyanotoxins [7,15]. These inhibit the eukaryotic protein phosphatases 1 and 2a, and have hepatotoxic effects in vertebrates [10,16,17]. Drinking water from surface water supplies must therefore be checked for microcystin content, and may not be higher than 1 µg microcystin L −1 according to WHO regulation. Microcystins are cyclic heptapeptides (Figure 1) and are produced by several cyanobacteria including Microcystis, Planktothrix, and Anabaena (Dolichospermum) [14,18,19]. The common structure and biosynthetic pathway of microcystin synthesis in these genera have been described [20][21][22][23][24][25]. In Microcystis, the microcystin synthetase gene cluster co...

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Section: Discussionmentioning

confidence: 99%

High Diversity of Microcystin Chemotypes within a Summer Bloom of the Cyanobacterium Microcystis botrys

Johansson

Legrand

Björnerås

et al. 2019

Toxins

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“…Their phylogenetic identity was previously assessed based on the 16S rDNA gene sequence, which confirmed that they belong to the M. aeruginosa species. In the same study, the toxic potential of the strains was analyzed using the matrix-assisted laser desorption/ionization time-of-flight technique (MALDI TOF-MS), which showed that two of the strains (AICB 318 and AICB 702) produced toxins 27 . The organisms were grown as batch cultures in BG11 medium, pH 7.5 41 , at 22–25 °C and a constant light intensity of 20 μmol m −2 s −1 .…”

Section: Methodsmentioning

confidence: 99%

“…In this paper, the transition from blooms to scums (the process of scum formation itself) in eight recently isolated M. aeruginosa strains was analyzed. The strains were isolated from various freshwaters across Romania, and they were previously described in terms of molecular phylogeny and toxic potential 27 . The main hypothesis was that different strains, although belonging to the same species, would display divergent behaviors when exposed to certain conditions, both for triggering or preventing scum formation.…”

Section: Introductionmentioning

confidence: 99%

The impact of cation concentration on Microcystis (cyanobacteria) scum formation

Drugă

Buda

Szekeres

et al. 2019

Sci Rep

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Cyanobacterial scums at the surface of the lakes are potentially harmful phenomena with increasing occurrence in the last decades, and the causes that lead to their formation are still an unresolved issue. In order to better understand what triggers the scums, we investigated the effect of several Mg 2+ and Ca 2+ ion concentrations in promoting them in eight Microcystis aeruginosa strains. The possibility to prevent scum formation by using the ion chelator EDTA was also explored. We found that in some strains the cell aggregation takes place under lower ion source concentrations (20 mM MgSO 4 or CaCl 2 ), while in others this phenomenon does not occur even at 60 mM concentration. The scum formation correlated to the amount of extracellular polymeric substances (between 234 and 351 µg/cell). EDTA failed to prevent the scum formation in most strains, and in turn it caused cell lysis followed by the release of cellular content into the culture medium. We emphasize the relevance of these results for cyanobacterial scum formation in the environment and we also suggest that controlling the salinity of the medium (by manipulating the ion concentration) is a potentially efficient method for biomass harvesting in large ponds/tanks.

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Decoding cyanobacterial phylogeny and molecular evolution using an evonumeric approach

Singh

Aboal

et al. 2014

Protoplasma

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Forty-one heterocystous cyanobacteria strains representing 12 cyanobacterial genera collected from all across India were assessed in phylogenetic and evolutionary perspectives. The structural gene 16S ribosomal RNA (rRNA) and the functional genes nifD and psbA were selected as molecular chronometers in this study. The phylogenetic analyses demonstrated the monophyly of heterocystous cyanobacteria with significant intermixing, along with establishing the polyphyly of Stigonematales, strongly supporting the need for re-amendments in cyanobacterial taxonomy and systematics. Molecular trends obtained did not clearly reflect the phenotypic affiliations, thus advocating for genetic characterizations using more molecular markers. Large-scale evonumeric extrapolations of gene sequence data of all the three molecular markers was performed to assess the evolutionary pace of heterocystous cyanobacteria on the basis of nucleotide diversity, recombination frequencies, and the DNA divergence between the sampled taxa. The obtained results tilted the evolutionary pace in favor of the less complex Nostocales thus indicating that possibly the simple non-branched forms are more flexible and adaptive for evolutionary diversifications as compared to the more complex and branched ones. This study hence represents a unique blend of molecular phylogeny with evogenomic sequence analyses for understanding the genetic diversity, phylogeny, and evolutionary pace within the heterocystous cyanobacteria.

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Molecular characterization of microcystin-producing cyanobacteria from Romanian fresh waters

Cited by 4 publications

References 25 publications

High Diversity of Microcystin Chemotypes within a Summer Bloom of the Cyanobacterium Microcystis botrys

High Diversity of Microcystin Chemotypes within a Summer Bloom of the Cyanobacterium Microcystis botrys

The impact of cation concentration on Microcystis (cyanobacteria) scum formation

Decoding cyanobacterial phylogeny and molecular evolution using an evonumeric approach

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