Search Results (41)

The previous discovery of genomes of Polinton-like viruses (PLVs) associated with viruses of Chrysochromulina parva stimulated this research to determine the biological nature of these putative viral hyperparasites. Purification of C. parva viruses to enable co-infection experiments led to the discovery of a previously unknown virus, CpV-BQ3, which, based on sequence information and electron microscopy, is a species of Tethysvirus, a genus within the Megaviricetes. Purification and TEM imaging of CpV-PLV Moe revealed naked icosahedral particles morphologically similar to other cultivated virophages and PLVs. Mixed-infection experiments with the putative Polinton-like virus CpV-PLV Moe demonstrated that CpV-BQ3 supports its replication, whereas the putative Phycodnavirus CpV-BQ1 does not. Further, experimental infections with differing proportions of the Moe and its helper virus CpV-BQ3 revealed a dose-effect whereby high levels of Moe had a greater negative impact on BQ3 replication compared to lower levels. Conversely, high levels of Moe relative to BQ3 provided greater protection for C. parva, allowing enhanced cell survival, whereas low doses of Moe did not prevent cell lysis. Overall, the results of this study demonstrated the intimate relationship of CpV-PLV Moe with the newly discovered virus, CpV-BQ3, and C. parva, and illustrate the complex ecology of algal viruses. Full article

In the summer of 2022, a massive toxic algal bloom of the haptophyte Prymnesium parvum devastated the Oder River in Poland and Germany. Between the end of July and the beginning of September, an estimated hundred thousand fish, mussels, and aquatic snails died. Since then, Prymnesium parvum has been established in the river network, as confirmed by monthly sampling, and there is the potential that such a catastrophe could repeat itself. Here, we report the occurrence of an apparently non-toxic bloom of the ‘golden algae’ Prymnesium parvum in May and June 2024 at comparable abundances to the ones observed during 2022, with a maximum abundance of 120,000 cell equivalents (CE)/mL in the main stem river without any associated fish deaths. Interestingly, in July 2024, local blooms in the West Oder even exceeded these abundances (160,000 CE/mL). The main-stem abundances decreased to 850–4250 CE/mL in July and 5–500 CE/mL in August. During the bloom, no mass mortalities of aquatic organisms were reported despite high abundances. Nutrients (total nitrogen TN, total phosphorus TP, N:P ratio) were inconspicuous and comparable to the disaster in 2022. To our knowledge, this is the first record of a massive Prymnesium bloom that did not result in mass fish deaths. Full article

In the summer of 2022, massive blooms of the toxic haptophyte Prymnesium parvum triggered one of the most significant ecological disasters ever recorded in the Odra River, resulting in massive fish and mollusk kills and severe economic damage. Having shown promise for treating other types of phytoplankton blooms, we applied various concentrations of hydrogen peroxide (HP) in an experimental setting using waters collected from the Gliwice Canal; a location with extensive proliferations of P. parvum. In the first stage of our experiment, a single application as low as 14 mg H₂O₂/L successfully reduced P. parvum biomass and prymnesin concentrations, measured using newly obtained prymnesin standards, with limited negative impact on other phytoplankton. In the second stage of the experiment, we reintroduced an inoculum of the canal water containing the haptophyte bloom. The simulated renewal of the phytoplankton community led to higher P. parvum biomass and elevated prymnesin concentrations, possibly due to nutrient release after HP application or reduced phytoplankton competition. We observed differences in the toxin profile compared with control conditions, suggesting changes in the haptophyte ecotypes in the experimental treatments. The results suggest that HP can be successfully used to combat P. parvum blooms, though caution is warranted with higher concentrations. Full article

This study provides the first systematic characterization of culturable yeast diversity associated with large-scale cultivation of Tisochrysis lutea. This marine haptophyte is widely used in aquaculture for its high content of essential fatty acids, pigments, and other bioactive compounds. Culture sampling was conducted at Necton S.A. facilities (Olhão, Portugal) over full production cycles from 5 L flasks until tubular photobioreactors during the months of May and June. The study aimed to identify and isolate the present yeast species and evaluate their physiological traits relevant to potential co-cultivation strategies. All retained isolates belonged to the phylum Basidiomycota, with six species identified: Rhodotorula sphaerocarpa (45%), R. mucilaginosa (20%), R. diobovata (13%), Vishniacozyma carnescens (16%), Naganishia diffluens (3%), and Moesziomyces aphidis (3%). Temperature growth profiles (10–40 °C), tolerance to artificial sea water, and auxin production were characterized, revealing that, except for V. carnescens, the yeast isolates grow optimally at 25–30 °C, within the ideal range for T. lutea cultivation. Results suggest that some of these marine yeasts, particularly R. sphaerocarpa and R. mucilaginosa isolates, could serve as biological enhancers of algal productivity, in situ. This foundational work supports future efforts to develop targeted yeast management or co-cultivation strategies, with the goal of improving biomass yield and metabolite production in industrial T. lutea photobioreactors. Full article

The calcareous nannoplankton comprises haptophyte eukaryotes known as coccolithophores, capable of calcifying elaborate external skeletons (coccoliths s.l.) which differ morphologically depending on the phase of the life cycle considered, and the locus (intra- or extracellular) of mineralization. No study is currently available that analyzes the impact of these differences on coccolith morphology. An analysis of the assembly of their crystals is conducted here in search of the following: (1) identical traits across life cycles; (2) fossil records diagnostic of extracellular calcification; and (3) influence of the geometry of biomineralization during the diploid phase on the long-term evolution of a clade. This study shows patterns such as correlation of characters and structural imprint that unify the haploid and diploid phases, indicating a strong cellular integrity and offering potent means to determine life cycles in living and fossil communities. It also shows that differences in diversity patterns and longevity among families and orders depend on coccolith geometry, concentric geometry being more favorable to stability, and superposition geometry facilitating morphological diversification. Extinction occurs when the potential for diversification is attained. Finally, I propose that the evolution of biomineralization in the calcareous nannoplankton may have been more complex than initially thought, with intra- and extracellular calcification evolving independently. Full article

The modern Arctic is characterized by a decreased ice cover and significant interannual variability. However, the reaction of the High Arctic ecosystem to such changes is still being determined. This study tested the hypothesis that the key drivers of changes in phytoplankton are the position and intensity of Atlantic water (AW) flow. The research was conducted in August 2017 in the northern part of the Barents Sea and in August 2020 in the Nansen Basin. In 2017, the Nansen Basin was ice covered; in 2020, the Nansen Basin had open water up to 83° N. A comparative analysis of phytoplankton composition, dominant species, abundance, and biomass at the boundary of the ice and open water in the marginal ice zone (MIZ) as well as in the open water was carried out. The total biomass of the phytoplankton in the photic layer of MIZ is one and a half orders of magnitude greater than in open water. In 2017, the maximum abundance and biomass of phytoplankton in the MIZ were formed by cold-water diatoms Thalassiosira spp. (T. gravida, T. rotula, T. hyalina, T. nordenskioeldii), associated with first-year ice. They were confined to the northern shelf of the Barents Sea. The large diatom Porosira glacialis grew intensively in the MIZ of the Nansen Basin under the influence of Atlantic waters. A seasonal thermocline, above which the concentrations of silicon and nitrogen were close to zero, and deep maxima of phytoplankton abundance and biomass were recorded in the open water. Atlantic species—haptophyte Phaeocystis pouchettii and large diatom Eucampia groenlandica—formed these maxima. P. pouchettii were observed in the Nansen Basin in the Atlantic water (AW) flow (2020); E. groenlandica demonstrated a high biomass (4848 mg m⁻³, 179.5 mg C m⁻³) in the Franz Victoria trench (2017). Such high biomass of this species in the northern Barents Sea shelf has not been observed before. The variability of the phytoplankton composition and biomass in the Franz Victoria trench and in the Nansen Basin is related to the intensity of the AW, which comes from the Frame Strait as the Atlantic Water Boundary Current. Full article

The recognition and use of algae in the very trend-driven cosmetic industry is progressively increasing. Up to now, the main focus was on large seaweeds and a limited number of microalgae. However, motile microalgae, flagellates, remain underscored in this aspect, although some of them are utilized commercially. Flagellates from different taxonomic groups occupy various habitats and contain bioactive high-value multifunctional compounds, some of which are novel. Moreover, they may simultaneously produce different substances, which together with the development of downstream processing technologies, makes them a promising source for modern biotechnology. The present review covers data on 411 strains, 251 species from 110 genera from 6 phyla, and is oriented generally towards less explored flagellates. It demonstrates their great potential as bearers of interesting novel compounds that can be beneficially applied in modern cosmetics. Safety aspects of both sources and products are also discussed. Considering the gaps in the knowledge, the necessity to expand the research on both well-known and yet unexplored microalgae is shown, encouraging the development of upstreaming processes, including phycoprospecting. Last but not least, this paper outlines the role of living culture collections and of using good taxonomic expertise before running the biochemical tests, cultivation, and bioengineering experiments. Full article

Microscopic eukaryotes are important components of coastal wetland ecosystems. The goal of this study was to investigate the diversity of microeukaryotes in the tidal pools of a New Jersey salt marsh and to compare the assemblages of natural and artificial pools excavated for controlling mosquito populations. We evaluated microeukaryotic assemblages using the amplicon sequencing of 18S and rbcL DNA markers and the microscopic identification of diatoms in water and sediment samples. 18S unique amplicon sequence variants (ASV) representing ciliates, dinoflagellates, diatoms, and cercozoans were the most diverse, while the reads of dinoflagellates, diatoms, ciliates, and nematodes were the most abundant. The dominant ASVs were attributed to organisms that are characteristic of coastal plankton and sediments or those known for their resistance to salinity, desiccation, hypoxia, and UV stress. The sediment assemblages were more diverse compared to those from the water column and contained a larger portion of ASVs that were not assigned to any low-rank taxa, reflecting the current gaps in understanding the diversity of microeukaryotes. Most taxonomic groups were significantly different in their abundance and composition between natural and artificial pools. Dinoflagellates, haptophytes, chrysophytes, pelagophytes, and raphidophytes—the groups that include a large proportion of mixotrophic taxa and species known for forming harmful algal blooms—were more abundant in the artificial than in the natural pools. Fungi, labyrinthulomycetes, and peronosporomycetes were also more abundant in artificial pools, which may be related to organic matter enrichment. Diatoms and foraminifera showed an opposite trend of higher abundance in natural pools. Full article

Algae and bacteria have co-occurred and coevolved in common habitats for hundreds of millions of years, fostering specific associations and interactions such as mutualism or antagonism. These interactions are shaped through exchanges of primary and secondary metabolites provided by one of the partners. Metabolites, such as N-sources or vitamins, can be beneficial to the partner and they may be assimilated through chemotaxis towards the partner producing these metabolites. Other metabolites, especially many natural products synthesized by bacteria, can act as toxins and damage or kill the partner. For instance, the green microalga Chlamydomonas reinhardtii establishes a mutualistic partnership with a Methylobacterium, in stark contrast to its antagonistic relationship with the toxin producing Pseudomonas protegens. In other cases, as with a coccolithophore haptophyte alga and a Phaeobacter bacterium, the same alga and bacterium can even be subject to both processes, depending on the secreted bacterial and algal metabolites. Some bacteria also influence algal morphology by producing specific metabolites and micronutrients, as is observed in some macroalgae. This review focuses on algal-bacterial interactions with micro- and macroalgal models from marine, freshwater, and terrestrial environments and summarizes the advances in the field. It also highlights the effects of temperature on these interactions as it is presently known. Full article

Background: In the search of a rapid and representative method for the approximate calculation of culture density and cell content of useful pigments, the study of absorption spectra of cultures of the dinoflagellate Amphidinium carterae, the haptophyte Isochrysis galbana, the chlorophyte Nephroselmis sp., and the filamentous cyanobacterium Anabaena sp. were selected as representative species of different taxa. Methods: The experimental cultures were established in small volumes by the discontinuous method under 20–21 °C, salinity of 30 or 40 ppt, and 2000 or 8000 lux illumination, and the absorbance spectra, density of the culture and concentration of the extracted pigments chlorophyll, total carotenoids, and phycocyanin were recorded during cultivation. Results: Algal density can be predicted sufficiently correctly because the regression equation of the correlation of the OD value of 750 nm from each absorption spectrum and the measured algal biomass was very strong. The same is true for the corresponding correlations between OD 750 nm and the detected pigments. Conclusions: Absorption spectra of microalgal cultures can be a simple, inexpensive, and non-invasive method for the growers to obtain the necessary information for predicting the right time to collect an ideal combination of maximum biomass and useful pigments, provided that the interpretation of the spectra is performed according to the method described herein. Full article

Cyanobacteria are the most common toxigenic algae in inland waters. Their toxins can affect the health of aquatic and terrestrial organisms, including humans. Other algal groups, such as haptophytes (e.g., Prymnesium parvum) and euglenoids (e.g., Euglena sanguinea), can also form harmful algal blooms (HABs) whose toxins cause injury to aquatic biota but currently have no known effects on human health. Prymnesium parvum, however, is responsible for some of the worst HAB-related ecological disasters recorded in inland waters. Here, we provide an overview of the primary toxigenic algae found in U.S. inland waters: cyanobacteria (planktonic forms), P. parvum, and E. sanguinea with the objective of describing their similarities and differences in the areas of HAB ecology, algal toxins, and the potential for future range expansion of HABs. A detailed account of bloom habitats and their known associations with land cover and use is provided from the perspective of water quality. This review revealed that salinity may have an influence on inland cyanobacterial blooms and cyanotoxins that had not been fully recognized previously. Full article

Coccolithophores are well-known haptophytes that produce small calcium carbonate coccoliths, which in turn contribute to carbon sequestration in the marine environment. Despite their important ecological role, only two of eleven haptophyte plastid genomes are from coccolithophores, and those two belong to the order Isochrysidales. Here, we report the plastid genomes of two strains of Ochrosphaera neapolitana (Coccolithales) from Spain (CCAC 3688 B) and the USA (A15,280). The newly constructed plastid genomes are the largest in size (116,906 bp and 113,686 bp, respectively) among all the available haptophyte plastid genomes, primarily due to the increased intergenic regions. These two plastid genomes possess a conventional quadripartite structure with a long single copy and short single copy separated by two inverted ribosomal repeats. These two plastid genomes share 110 core genes, six rRNAs, and 29 tRNAs, but CCAC 3688 B has an additional CDS (ycf55) and one tRNA (trnL-UAG). Two large insertions at the intergenic regions (2 kb insertion between ycf35 and ycf45; 0.5 kb insertion in the middle of trnM and trnY) were detected in the strain CCAC 3688 B. We found the genes of light-independent protochlorophyllide oxidoreductase (chlB, chlN, and chlL), which convert protochlorophyllide to chlorophyllide during chlorophyll biosynthesis, in the plastid genomes of O. neapolitana as well as in other benthic Isochrysidales and Coccolithales species, putatively suggesting an evolutionary adaptation to benthic habitats. Full article

The oligotrophy of the southern Adriatic Sea is characterized by seasonal stratification which enables nutrient supply to the euphotic layer. A set of interdisciplinary methods was used to elucidate the diversity and co-dependency of bacterio- and phytoplankton of the water column during the stratification period of July 2021. A total of 95 taxa were determined by microscopy: 58 diatoms, 27 dinoflagellates, 6 coccolithophores, and 4 other autotrophs, which included Chlorophyceae, Chrysophyceae, and Cryptophytes. Nanophytoplankton abundances were higher in comparison to microphytoplankton. The prokaryotic plankton community as revealed by HTS was dominated by Proteobacteria (41–73%), Bacteroidota (9.5–27%), and cyanobacteria (1–10%), while the eukaryotic plankton community was composed of parasitic Syndiniales (45–80%), Ochrophyta (2–18%), Ciliophora (2–21%), Chlorophytes (2–4%), Haptophytes (1–4%), Bacillariophyta (1–13%), Pelagophyta (0.5–12%) and Chrysophyta (0.5–3%). Flow cytometry analysis has recorded Prochlorococcus and photosynthetic picoeukaryotes as more abundant in deep chlorophyll maximum (DCM), and Synechococcus and heterotrophic bacteria as most abundant in surface and thermocline layers. Surface, thermocline, and DCM layers were distinct considering community diversity, temperature, and nutrient correlations, while extreme nutrient values at the beginning of the investigating period indicated a possible nutrient flux. Nutrient and temperature were recognized as the main environmental drivers of phytoplankton and bacterioplankton community abundance. Full article

The coccolithophorid Ochrosphaera neapolitana was reported for the first time from samples obtained during a large-scale mucilage event in the Sea of Marmara in May 2022 in a previous study. We also found this species in our samples obtained about a year ago (i.e., in June 2021). In our study, O. neapolitana was further isolated and produced in the laboratory as a monoculture for further investigations using electron microscopy and molecular methods. Ochrosphaera neapolitana was identified using a small sub-unit (SSU) rRNA sequence and subsequent phylogenetic analysis. During the laboratory experiments, O. neapolitana was surprisingly observed to produce conspicuous levels of mucilage as a skim layer in mono- or multi-species cultures, mainly comprising other diatom species. This observation could be a significant milestone in understanding the reasons and mechanisms of mucilage events that occur in the Sea of Marmara. Full article

Coccolithophores are unicellular marine algae belonging to the haptophyte group, characterized by the production of intricate calcium carbonate plates that adorn their cells and exhibit species-specific morphology. The Adriatic Sea has historically been the type locality of numerous phytoplankton species, including coccolithophores. However, since the initial description, many species have not been recorded during the frequent phytoplankton surveys in the Adriatic Sea. This was mainly because these surveys did not use electron microscopy, which is necessary for accurate species identification. In this study, we re-evaluate the coccolithophore species lists using historical records and compare them with recent surveys in the coastal and open waters of the Adriatic Sea. In light of changes in nomenclature resulting from clarification of the species’ life cycles, we update the taxonomic list of coccolithophore species occurring in the Adriatic. Full article