Search Results (13)

Gypsum ecosystems are constrained by extreme nutrient and water scarcity, where cyanoprokaryota interact with gypsophyte rhizospheres, influencing plant performance and soil biogeochemistry. This study examines three gypsophytes—Herniaria fruticosa, Helianthemum squamatum, and Teucrium libanitis—during winter and spring to characterize rhizospheric and bulk soil properties, assess enzymatic activity and nutrient cycling, identify cyanoprokaryota communities, and determine bioelement accumulation patterns in both Microcoleus chthonoplastes and gypsophytes. Physical, chemical, microbiological, and microscopic analyses were conducted across seasons. β-glucosidase activity showed species-specific responses to water pulses, particularly in Helianthemum squamatum. Seasonal differences in water-soluble C and N distinguished rhizospheres of Teucrium libanitis and Helianthemum squamatum. Key soil drivers included water-holding capacity to −1500 kPa, total and organic carbon, and Cr content. Cyanoprokaryota exhibited both rhizosphere-specific (Gloeocapsa novacekii, Pseudocapsa dubia) and ubiquitous taxa, with Microcoleus chthonoplastes reflecting bioaccumulation strategies. Bioelement accumulation differed between leaves and roots, especially for K, Mn, Zn, Na, Ni, C, and V, while the Sr:Ca ratio emerged as a potential indicator, especially in Herniaria fruticosa. These findings highlight the role of cyanoprokaryota in regulating nutrient availability and enzymatic activity, supporting gypsophyte adaptation and the ecological sustainability and resilience of gypsum ecosystems, and informing conservation and restoration strategies in these neglected ecosystems. Full article

The present work focuses on seven megaliths sampled for the first time as a continuation of our studies on the biodiversity of algae on megaliths in Bulgaria. A total of 55 species from four divisions were identified (Chlorophyta was the richest with 31 species), of which 14 species are new for Bulgaria. Two species were of conservation concern, but six were potential toxin producers that could affect the health of visitors to the megaliths. Despite the general granitic character and relatively close location of the studied sites, their floristic similarity was low, with most algae (51 species) being rarely distributed (except Stichococcus bacillaris and Mychonastes homosphaera). The largest cult complex Paleokastro, furthest from populated areas, had the highest species diversity (22 species), while the lowest (8 species) was found in the highly exposed Kalinkin Kamuk, located in a village. The NMDS analysis tool showed the existence of four distinct ecological groups and that temperature and light are the most important drivers for the distribution of the epilithic algae on the investigated megaliths. Correlations with temperatures estimated to identify potential indicators or future survivors under global warming conditions were low, except for the Streptophyta. It was represented by four species of the genus Klebsormidium, which is known for its high ecological tolerance and drought resistance. Extending the studies on lithophytic algae to megaliths is important for a better knowledge of their biodiversity and ecology, but also for the protection of megaliths and for understanding the impact of climate change on these fragile monuments. Full article

Thermal algae are extremophilic organisms that live in one of the harshest environments in the world and thrive in waters with temperatures of up to 90 °C. They have gained attention due to their special ecological adaptations, their great biotechnological potential and their recently recognised role in combating global climate change and achieving sustainable development. However, the biodiversity of these algae is far from being fully explored. The article presents the first finding of the prokaryotic genus Asterocapsa (Chroococcales, Cyanophyceae, Cyanoprokaryota/Cyanobacteria) in thermal waters and describes a new species from the fountain basins in the thermal system of the only continental European geyser (101 °C) in the town of Sapareva Banya (south-west Bulgaria). This species is not only one of the few aquatic representatives of this generally aeroterrestrial genus, but is also characterised by its extremophilic lifestyle and differs clearly from the type species and other aquatic species of the genus due to its morphological characteristics. These include the smaller dimensions of the cells and colonies, as well as the colourless, transparent, but always lamellar and regularly verrucous mucilage envelopes. The unique locality of this alga is highly endangered and was included in the first Red List of Bulgarian wetlands. Due to human activities and changes in the geyser system, we have detected some unfavourable changes in the algal habitat and therefore propose to add the newly described species to the Red List of Bulgarian Microalgae with the status Critically Endangered. Full article

Microorganisms in high-salinity environments play a critical role in biogeochemical cycles, primary production, and the biotechnological exploitation of extremozymes and bioactive compounds. The main challenges in current research include isolating and cultivating these microorganisms under laboratory conditions and understanding their complex adaptive mechanisms to high salinity. Currently, universally recognized protocols for isolating microalgae and cyanobacteria from salt pans, salterns, and similar natural habitats are lacking. Establishing axenic laboratory cultures is essential for identifying new species thriving in high-salinity environments and for exploring the synthesis of high-value metabolites by these microorganisms ex situ. Our ongoing research primarily focuses on photosynthetic microorganisms with significant biotechnological potential, particularly for skincare applications. By integrating data from the existing literature with our empirical findings, we propose a standardized pipeline for the isolation and laboratory cultivation of microalgae and cyanobacteria originating from aqueous environments characterized by elevated salt concentrations, such as solar salterns. This approach will be particularly useful for researchers working with microorganisms adapted to hypersaline waters. Full article

Microalgae offer a promising alternative for heavy metal removal, and the search for highly efficient strains is ongoing. This study investigated the potential of two microalgae, Coelastrella sp. BGV (Chlorophyta) and Arthronema africanum Schwabe & Simonsen (Cyanoprokaryota), to bind zinc ions (Zn²⁺) and protect higher plants. Hydroponically grown pea (Pisum sativum L.) seedlings were subjected to ZnSO₄ treatment for 7 days in either a nutrient medium (Knop) or a microalgal suspension. The effects of increasing Zn²⁺ concentrations were evaluated through solution parameters, microalgal dry weight, pea growth (height, biomass), and physiological parameters, including leaf gas exchange, chlorophyll content, and normalized difference vegetation index (NDVI). Zinc accumulation in microalgal and plant biomass was also analyzed. The results revealed that microalgae increased pH and oxygen levels in the hydroponic medium while enhancing Zn accumulation in pea roots. At low ZnSO₄ concentrations (2–5 mM), microalgal suspensions stimulated pea growth and photosynthetic performance. However, higher ZnSO₄ levels (10–15 mM) caused Zn accumulation, leading to nutrient deficiencies and growth suppression in microalgae, which ultimately led to physiological disturbances in peas. Coelastrella sp. BGV exhibited greater tolerance to Zn stress and provided a stronger protective effect when co-cultivated with peas, highlighting its potential for phycoremediation applications. Full article

This paper presents the first data on the biodiversity of lithophytic algae from Bulgarian megaliths obtained after the application of the direct sampling method, subsequent cultivation, and processing by light microscopy. A rich algal flora was found: 90 species and 1 variety of 65 genera from Cyanoprokaryota/Cyanobacteria (29 species, 13 genera), Chlorophyta (40 species and 1 variety, 38 genera), Streptophyta (5 species, 1 genus), and Ochrophyta (16 species, 13 genera). Among them were the globally rare Pseudodictyochloris multinucleata (Chlorophyta), found for the first time in such lowland and warm habitats, and Scotiella tuberculata (Chlorophyta), for which this is the first finding in the country. Three of the recorded species are conservationally important. The low floristic similarity between the sites (0–33%) shows the diversity of the algal flora, with no common species found for all the megaliths studied. The most widespread were the strongly adaptive and competitive Stichococcus bacillaris, Apatococcus lobatus, and Chloroidium ellipsoidium (Chlorophyta). The correlations estimated between the species number and substrate temperature (18.1–49.6 °C) suggest the prospect of future research related to the impact of global warming. In addition, the study points to the safety aspects as it revealed species from nine potentially toxin-producing cyanoprokaryotic genera that could be harmful to visitors’ health. Full article

Limnospira fusiformis (also known as Spirulina) is a cyanobacterium that is widely cultivated due to its economic importance. It has specific pigments such as phycocyanin that allow it to grow at different light wavelengths compared to other cultivated algae. Our study investigated the effect of yellow (590 nm) and blue (460 nm) light fields on various biochemical features, including the pigment concentration, protein content, dry weight, and cell ultrastructure of L. fusiformis. Our findings revealed that biomass growth was faster in yellow light compared to blue light, with a higher relative amount of proteins even after one day of exposure. However, after eight days, the relative protein content in yellow versus blue light was not statistically different. Furthermore, in yellow light, we observed a decrease in chlorophyll a, an increase in cyanophycin granules, and an increase in the amount of dilated thylakoids. On the other hand, in blue light, there was an increase in phycocyanin after one day, along with an increase in electron-dense bodies, which are attributable to carboxysomes. However, after eight days, the differences in pigment content compared to the control were not statistically significant. Our study showed that using specific wavelengths during the harvesting phase of spirulina growth can enhance phycocyanin content with blue light (after one day) and biomass, growth rates, and protein content with yellow light after six days. This highlights the biotechnological potential of this approach. Full article

The general awareness of the threats on biodiversity and water quality raised the number of studies that use phytoplankton in assessment procedures. Since most metrics require obtaining mean values, this paper presents data that may help speed up field work and find indicators for a rapid water quality assessment based on single samplings, allowing simultaneous work on many sites. The phytoplankton from 43 Bulgarian waterbodies collected during three summer campaigns (2018, 2019, 2021) at sites selected after drone observations was studied by conventional light microscopy (LM) and an HPLC analysis of marker pigments. Our results allowed us to recommend drones and the HPLC application as reliable methods in rapid water quality assessments. In total, 787 algae from seven phyla (53 alien, new for Bulgaria) were identified. Chlorophyta was the taxonomically richest group, but Cyanoprokaryota dominated the biomass in most sites. New PCR data obtained on anatoxin and microcystin producers confirmed the genetic diversity of Cuspidothrix and Microcystis and provided three new species for the country’s toxic species, first identified by LM. A statistical analysis revealed significant correlations of certain algal phyla and classes with different environmental variables, and their species are considered promising for future search of bioindicators. This is especially valid for the class Eustigmatophyceae, which, as of yet, has been almost neglected in water assessment procedures and indices. Full article

The paper presents the first proof of planktonic cyanoprokaryote genus Cuspidothrix as an anatoxin A (ATX) producer in Bulgarian wetlands. The results from polymerase chain reaction (PCR) obtained from two summer sampling campaigns in 26 selected lakes and reservoirs demonstrated presence of the anaC gene, responsible for ATX production in 21 strains of the genus. They were found in three waterbodies sampled in 2018 (coastal lake Vaya, coastal reservoir Poroy, inland reservoir Sinyata Reka) and in four waterbodies sampled in 2019 (inland reservoirs Duvanli, Koprinka, Plachidol 2, Sinyata Reka). The detected genetic diversity generally corresponds to the observations conducted by conventional light microscopy, by which we distinguished three species of Cuspidothrix (Cuspidothrix issatschenkoi, Cuspidothrix elenkinii and Cuspidothrix tropicalis, the latter considered alien in the country). Eleven strains showed high similarity to two sequences of C. issatschenkoi available from the National Centre for Biotechnology Information (NCBI). Ten other strains assembled in a group, which—in lack of available from NCBI genetic sequences—were presumed related to C. tropicalis and C. elenkinii after comparison with the results from light microscopy. Cuspidothrix strains found in Bulgarian waterbodies showed high genetic similarity to those isolated and sequenced from Asia (Japan, China) and Northern Europe (Norway, Finland). Full article

Microscopic prokaryotic and eukaryotic algae (microalgae), which can be effectively grown in mass cultures, are gaining increasing interest in cosmetics. Up to now, the main attention was on aquatic algae, while species from aeroterrestrial and extreme environments remained underestimated. In these habitats, algae accumulate high amounts of some chemical substances or develop specific compounds, which cause them to thrive in inimical conditions. Among such biologically active molecules is a large family of lipids, which are significant constituents in living organisms and valuable ingredients in cosmetic formulations. Therefore, natural sources of lipids are increasingly in demand in the modern cosmetic industry and its innovative technologies. Among novelties in skin care products is the use of lipid nanoparticles as carriers of dermatologically active ingredients, which enhance their penetration and release in the skin strata. This review is an attempt to comprehensively cover the available literature on the high-value lipids from microalgae, which inhabit aeroterrestrial and extreme habitats (AEM). Data on different compounds of 87 species, subspecies and varieties from 53 genera (represented by more than 141 strains) from five phyla are provided and, despite some gaps in the current knowledge, demonstrate the promising potential of AEM as sources of valuable lipids for novel skin care products. Full article

This article gives a comprehensive overview on potentially harmful algae occurring in the built environment. Man-made structures provide diverse habitats where algae can grow, mainly aerophytic in nature. Literature reveals that algae that is potentially harmful to humans do occur in the anthropogenic environment in the air, on surfaces or in water bodies. Algae may negatively affect humans in different ways: they may be toxic, allergenic and pathogenic to humans or attack human structures. Toxin-producing alga are represented in the built environment mainly by blue green algae (Cyanoprokaryota). In special occasions, other toxic algae may also be involved. Green algae (Chlorophyta) found airborne or growing on manmade surfaces may be allergenic whereas Cyanoprokaryota and other forms may not only be toxic but also allergenic. Pathogenicity is found only in a special group of algae, especially in the genus Prototheca. In addition, rare cases with infections due to algae with green chloroplasts are reported. Algal action may be involved in the biodeterioration of buildings and works of art, which is still discussed controversially. Whereas in many cases the disfigurement of surfaces and even the corrosion of materials is encountered, in other cases a protective effect on the materials is reported. A comprehensive list of 79 taxa of potentially harmful, airborne algae supplemented with their counterparts occurring in the built environment, is given. Due to global climate change, it is not unlikely that the built environment will suffer from more and higher amounts of harmful algal species in the future. Therefore, intensified research in composition, ecophysiology and development of algal growth in the built environment is indicated. Full article

Bulgaria, situated on the Balkan Peninsula, is rich in small and shallow, natural and man-made non-lotic waterbodies, which are threatened by blooms of Cyanoprokaryota/Cyanobacteria. Although cyanotoxins in Bulgarian surface waters are receiving increased attention, there is no information on microviridins and their producers. This paper presents results from a phytoplankton study, conducted in August 2019 in three lakes (Durankulak, Vaya, Uzungeren) and five reservoirs (Duvanli, Mandra, Poroy, Sinyata Reka, Zhrebchevo) in which a molecular-genetic analysis (PCR based on the precursor mdnA gene and subsequent translation to amino acid alignments), combined with conventional light microscopy and an HPLC analysis of marker pigments, were applied for the identification of potential microviridin producers. The results provide evidence that ten strains of the genus Microcystis, and of its most widespread species M. aeruginosa in particular, are potentially toxigenic in respect to microviridins. The mdnA sequences were obtained from all studied waterbodies and their translation to amino-acid alignments revealed the presence of five microviridin variants (types B/C, Izancya, CBJ55500.1 (Microcystis 199), and MC19, as well as a variant, which was very close to type A). This study adds to the general understanding of the microviridin occurrence, producers, and sequence diversity. Full article

The aim of the research was to determine the successional changes proceeding in the phytoplankton of a lake. The basis of the study was the analysis of long-term seasonal changes in the taxonomic structure and the estimation of the intensity of algal community development in phytoplankton of Lake Kortowskie. Seasonal changes in the phytoplankton taxonomic structure manifested themselves as a decreasing share of Bacillariophyceae in spring and autumn and Chlorophyta in summer phytoplankton. The retreating chlorophytes and the diatoms were replaced by blue-green algae, the increasing share of which caused a reduction in the stability of the remaining phytoplankton taxonomic groups, and consequently, taxonomic shifts and progressive development of the overall phytoplankton community in all phenological seasons. Intensive algal growth was observed in spring and lasted until late autumn. The highest phytoplankton biomass was always recorded in summer. Summer phytoplankton development was related to increased bluegreen algae domination, the massive growth of which was observed from spring to autumn. The development of the Cyanoprokaryota community had a negative impact on the diatoms, since the latter earlier disappeared from the biocenosis in spring and re-developed to a lesser degree in autumn. Full article