Adriana Hegedus
Research Scientist II - Taxonomy and Ecology
Biography
As a research scientist, I am deeply fascinated by the diverse ways in which life manifests itself in the complex world of microscopic photosynthetic micro-organisms (phytoplankton).
Publications
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article
Quantifying Evolutionary Changes To Temperature-Co2 Growth Response Surfaces In Skeletonema Marinoi After Adaptation To Extreme Conditions |
Briddon Charlotte L.; Nicoara Maria; Hegedus Adriana; Thomas Mridul K.; Druga Bogdan | Isme Communications, 2025 | |
AbstractGlobal warming and ocean acidification are having an unprecedented impact on marine ecosystems, yet we do not yet know how phytoplankton will respond to simultaneous changes in multiple drivers. To better comprehend the combined impact of oceanic warming and acidification, we experimentally estimated how evolution shifted the temperature-CO2 growth response surfaces of two strains of Skeletonema marinoi that were each previously adapted to four different temperature x CO2 combinations. These adapted strains were then grown under a factorial combination of five temperatures and five CO2 concentrations to capture the temperature-CO2 response surfaces for their unacclimated growth rates. The development of the first complete temperature-CO2 response surfaces showed the optimal CO2 concentration for growth to be substantially higher than expected future CO2 levels (similar to 6000 ppm). There was minimal variation in the optimal CO2 concentration across the tested temperatures, suggesting that temperature will have a greater influence on growth rates compared to enhanced CO2. Optimal temperature did not show a unimodal response to CO2, either due to the lack of acclimation or the highly efficient CO2 concentrating mechanisms, which diatoms (e.g. Skeletonema) can up-/downregulate depending on the CO2 conditions. We also found that both strains showed evidence of evolutionary shifts as a result of adaptation to temperature and CO2. The evolutionary response differed between strains, underscoring how genetic differences (perhaps related to historical regimes) can impact phytoplankton performance. Understanding how a dominant algal species responds to multiple drivers provides insight into real-world scenarios and helps construct theoretical predictions of environmental change. |
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article
Desmodesmus Pseudoperforatus Sp. Nov., A Giant In Desmodesmus, Series Maximi |
Hegedus Adriana; Porav Alin Sebastian; Tripon Septimiu Cassian; Dragos Nicolae | European Journal Of Phycology, 2024 | |
AbstractSeries Maximi is a group within Desmodesmus (Chlorophyta) which contains the three species D. maximus, D. perforatus and D. tropicus. Besides their large cell sizes, the most striking morphological trait unique to the members of this genus is the presence of large perforations between the coenobial cells. The perforations are either present (D. perforatus and D. tropicus) or the space between the cells is completely sealed (D. maximus). We report here a fourth species of the series based on two strains (AICB 1155 and AICB 1572) from freshwater environments of the Danube Delta, Romania. The ultrastructure of the cell walls revealed a partial closure of the space between the cells which creates slightly visible perforations in light microscopy. Analyses of DNA sequences and secondary structure of the ITS2 fragment by coalescent (PTP, GMYC), distance (ASAP), and evolutionary modelbased methods (ML, BI) indicated a fourth candidate species which included both the AICB strains investigated and other strains with similar morphological traits from reference literature. Despite its poor representation in public databases, analysis of the SSU rDNA gene for the series Maximi strengthened the ITS2 results. Therefore, based on its larger cell sizes relative to the other members of the series, cell morphology, the presence of partial perforations and other peculiarities of the cell wall ultrastructure, the independent phylogenetic position, CBCs analysis, and a different 'DNA signature' within the ITS2 fragment we suggest that this clade should be described as a new taxon of the series Maximi, Desmodesmus pseudoperforatus sp. nov. HIGHLIGHTS center dot Morphological differences and DNA-based lines of evidence indicate new species. center dot Microperforations of the space between the coenobial cells. center dot Strains have the largest cell sizes in the series Maximi. |
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article
Municipal Wastewaters Carry Important Carbapenemase Genes Independent Of Hospital Input And Can Mirror Clinical Resistance Patterns |
Teban-Man Adela; Szekeres Edina; Fang Peiju; Klumper Uli; Hegedus Adriana; Baricz Andreea; Berendonk Thomas Ulrich; Parvu Marcel; Coman Cristian | Microbiology Spectrum, 2022 | |
AbstractThe spatiotemporal variation of several carbapenemase-encoding genes (CRGs) was investigated in the influent and effluent of municipal WWTPs, with or without hospital sewage input. Correlations among gene abundances, bacterial community composition, and wastewater quality parameters were tested to identify possible predictors of CRGs presence. Also, the possible role of wastewaters in mirroring clinical resistance is discussed. The taxonomic groups and gene abundances showed an even distribution among wastewater types, meaning that hospital sewage does not influence the microbial diversity and the CRG pool. The bacterial community was composed mainly of Proteobacteria, Firmicutes, Actinobacteria, Patescibacteria, and Bacteroidetes. Acinetobacter spp. was the most abundant group and had the majority of operational taxonomic units (OTUs) positively correlated with CRGs. This agrees with recent reports on clinical data. The influent samples were dominated by bla(KPC), as opposed to effluent, where bla(IMP) was dominant. Also, bla(IMP) was the most frequent CRG family observed to correlate with bacterial taxa, especially with the Mycobacterium genus in effluent samples. Bacterial load, bla(NDM), bla(KPC), and bla(OXA-48) abundances were positively correlated with BOD5, TSS, HEM, Cr, Cu, and Fe concentrations in wastewaters. When influent gene abundance values were converted into population equivalent (PE) data, the highest copies/1 PE were identified for bla(KPC) and bla(OXA-48), agreeing with previous studies regarding clinical isolates. Both hospital and non-hospital-type samples followed a similar temporal trend of CRG incidence, but with differences among gene groups. Colder seasons favored the presence of bla(NDM), bla(KPC), and bla(OXA-48), whereas warmer temperatures show increased PE values for bla(VIM) and bla(IMP). IMPORTANCE Wastewater-based epidemiology has recently been recognized as a valuable, cost-effective tool for antimicrobial resistance surveillance. It can help gain insights into the characteristics and distribution of antibiotic resistance elements at a local, national, and even global scale. In this study, we investigated the possible use of municipal wastewaters in the surveillance of clinically relevant carbapenemase-encoding genes (CRGs), seen as critical antibiotic resistance determinants. In this matter, our results highlight positive correlations among CRGs, microbial diversity, and wastewater physical and chemical parameters. Identified predictors can provide valuable data regarding the level of raw and treated wastewater contamination with these important antibiotic resistance genes. Also, wastewater-based gene abundances were used for the first time to observe possible spatiotemporal trends of CRGs incidence in the general population. Therefore, possible hot spots of carbapenem resistance could be easily identified at the community level, surpassing the limitations of health care-associated settings. |
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article
Wastewaters, With Or Without Hospital Contribution, Harbour Mdr, Carbapenemase-Producing, But Not Hypervirulent Klebsiella Pneumoniae |
Teban-Man Adela; Farkas Anca; Baricz Andreea; Hegedus Adriana; Szekeres Edina; Parvu Marcel; Coman Cristian | Antibiotics-Basel, 2021 | |
AbstractCarbapenemase-producing Klebsiella pneumoniae (CPKP) isolated from influent (I) and effluent (E) of two wastewater treatment plants, with (S1) or without (S2) hospital contribution, were investigated. The strains belonged to the Kp1 phylogroup, their highest frequency being observed in S1, followed by S2. The phenotypic and genotypic hypervirulence tests were negative for all the strains tested. At least one carbapenemase gene (CRG), belonging to the blaKPC, blaOXA-48, blaNDM and blaVIM families, was observed in 63% of CPKP, and more than half co-harboured two to four CRGs, in different combinations. Only five CRG variants were observed, regardless of wastewater type: blaKPC-2, blaNDM-1, blaNDM-6, blaVIM-2, and blaOXA-48. Sequence types ST258, ST101 and ST744 were common for both S1 and S2, while ST147, ST525 and ST2502 were found only in S1 and ST418 only in S2. The strains tested were multi-drug resistant (MDR), all being resistant to beta-lactams, cephalosporins, carbapenems, monobactams and fluoroquinolones, followed by various resistance profiles to aminoglycosides, trimethoprim-sulphamethoxazole, tigecycline, chloramphenicol and tetracycline. After principal component analysis, the isolates in S1 and S2 groups did not cluster independently, confirming that the antibiotic susceptibility patterns and gene-type profiles were both similar in the K. pneumoniae investigated, regardless of hospital contribution to the wastewater type. |
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article
Desmodesmus Tropicus (Chlorophyta) In The Danube Delta - Reassessing The Phylogeny Of The Series Maximi |
Dragos Nicolae; Chiriac Cecilia; Porav Sebastian; Szoke-Nagy Tiberiu; Coman Cristian; Torok Liliana; Hegedus Adriana | European Journal Of Phycology, 2019 | |
AbstractDesmodesmus maximus (West & G.S.West) Hegewald, D. perforatus (Lemmermann) E.Hegewald and D. tropicus (W.B.Crow) E.Hegewald form the series Maximi within the genus Desmodesmus. Desmodesmus tropicus is a rare species although it is widely distributed in tropical regions including South-East Asia, South America and the USA. It is less common in temperate fresh waters, known only from Ukraine. In this study, we report for the first time its presence in the Danube Delta (Puiu Lake), Romania. The morphology and molecular phylogeny of two newly isolated strains were studied in relation to other strains of the genus Desmodesmus, series Maximi. Cell wall structures (rosettes, spines, tubes, honeycomb-shaped mesh with hexagonal units) which are important in the taxonomy of these algae were investigated by light-, scanning- and transmission electron microscopy. The phylogenetic position of the strains in the Algae and Cyanobacteria Culture Collection of the Institute of Biological Research was assessed using 18S rDNA sequences, ITS2 primary and secondary structures and by analysis of Compensatory Base Changes. Morphological traits and measurements of cells, coenobia and spines matched the description of D. tropicus, although some differences from the established morphological key (ridge-like structures resembling fine ribs) were also noticed. Identification as D. tropicus var. longiclathratus (Tell) Jeon & Hegewald was based on the presence of inner spines on four-celled and especially on eight-celled coenobia. The ITS2 sequence and secondary structure phylogeny supported the assignment of both AICB strains to D. tropicus, with no divergence from other D. tropicus sequences to support the identification of var. longiclathratus. Nevertheless, the morphological measurements and the ITS2 primary and secondary structure data indicated two distinct subclusters within D. tropicus, and a new possible taxon within the series Maximi. |
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article
Desmodesmus Tropicus (Chlorophyta) In The Danube Delta–Reassessing The Phylogeny Of The Series Maximi |
Dragoș N.; Chiriac C.; Porav S.; Szőke-Nagy T.; Coman C.; Tӧrӧk L.; Hegedűs A. | European Journal Of Phycology, 2019 | |
AbstractDesmodesmus maximus (West & G.S.West) Hegewald, D. perforatus (Lemmermann) E.Hegewald and D. tropicus (W.B.Crow) E.Hegewald form the series Maximi within the genus Desmodesmus. Desmodesmus tropicus is a rare species although it is widely distributed in tropical regions including South-East Asia, South America and the USA. It is less common in temperate fresh waters, known only from Ukraine. In this study, we report for the first time its presence in the Danube Delta (Puiu Lake), Romania. The morphology and molecular phylogeny of two newly isolated strains were studied in relation to other strains of the genus Desmodesmus, series Maximi. Cell wall structures (rosettes, spines, tubes, honeycomb-shaped mesh with hexagonal units) which are important in the taxonomy of these algae were investigated by light-, scanning- and transmission electron microscopy. The phylogenetic position of the strains in the Algae and Cyanobacteria Culture Collection of the Institute of Biological Research was assessed using 18S rDNA sequences, ITS2 primary and secondary structures and by analysis of Compensatory Base Changes. Morphological traits and measurements of cells, coenobia and spines matched the description of D. tropicus, although some differences from the established morphological key (ridge-like structures resembling fine ribs) were also noticed. Identification as D. tropicus var. longiclathratus (Tell) Jeon & Hegewald was based on the presence of inner spines on four-celled and especially on eight-celled coenobia. The ITS2 sequence and secondary structure phylogeny supported the assignment of both AICB strains to D. tropicus, with no divergence from other D. tropicus sequences to support the identification of var. longiclathratus. Nevertheless, the morphological measurements and the ITS2 primary and secondary structure data indicated two distinct subclusters within D. tropicus, and a new possible taxon within the series Maximi. © 2019, © 2019 British Phycological Society. |
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article
Differences In Temperature And Water Chemistry Shape Distinct Diversity Patterns In Thermophilic Microbial Communities |
Chiriac Cecilia M.; Szekeres Edina; Rudi Knut; Baricz Andreea; Hegedus Adriana; Dragos Nicolae; Coman Cristian | Applied And Environmental Microbiology, 2017 | |
AbstractThis report describes the biodiversity and ecology of microbial mats developed in thermal gradients (20 to 65 degrees C) in the surroundings of three drillings (Chiraleu [CH], Ciocaia [CI], and Mihai Bravu [MB]) tapping a hyperthermal aquifer in Romania. Using a metabarcoding approach, 16S rRNA genes were sequenced from both DNA and RNA transcripts (cDNA) and compared. The relationships between the microbial diversity and the physicochemical factors were explored. Additionally, the cDNA data were used for in silico functionality predictions, bringing new insights into the functional potential and dynamics of these communities. The results showed that each hot spring determined the formation of distinct microbial communities. In the CH mats (40 to 53 degrees C), the abundance of Cyanobacteria decreased with temperature, opposite to those of Chloroflexi and Proteobacteria. Ectothiorhodospira, Oscillatoria, and methanogenic archaea dominated the CI communities (20 to 65 degrees C), while the MB microbial mats (53 to 65 degrees C) were mainly composed of Chloroflexi, Hydrogenophilus, Thermi, and Aquificae. Alpha-diversity was negatively correlated with the increase in water temperature, while beta-diversity was shaped in each hot spring by the unique combination of physicochemical parameters, regardless of the type of nucleic acid analyzed (DNA versus cDNA). The rank correlation analysis revealed a unique model that associated environmental data with community composition, consisting in the combined effect of Na+, K+, HCO3-, and PO43- concentrations, together with temperature and electrical conductivity. These factors seem to determine the grouping of samples according to location, rather than with the similarities in thermal regimes, showing that other parameters beside temperature are significant drivers of biodiversity. IMPORTANCE Hot spring microbial mats represent a remarkable manifestation of life on Earth and have been intensively studied for decades. Moreover, as hot spring areas are isolated and have a limited exchange of organisms, nutrients, and energy with the surrounding environments, hot spring microbial communities can be used in model studies to elucidate the colonizing potential within extreme settings. Thus, they are of great importance in evolutionary biology, microbial ecology, and exobiology. In spite of all the efforts that have been made, the current understanding of the influence of temperature and water chemistry on the microbial community composition, diversity, and abundance in microbial mats is limited. In this study, the composition and diversity of microbial communities developed in thermal gradients in the vicinity of three hot springs from Romania were investigated, each having particular physicochemical characteristics. Our results expose new factors that could determine the formation of these ecosystems, expanding the current knowledge in this regard. |
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article
Molecular Phylogeny Of Botryococcus Braunii Strains (Race A) - An Integrative Approach |
Hegedus Adriana; Mocan Aurel; Barbu-Tudoran Lucian; Coman Cristian; Dragos Nicolae | Algal Research-Biomass Biofuels And Bioproducts, 2016 | |
AbstractBotryococcus braunii is a green colonial microalga which produces large quantities of liquid hydrocarbons similar to fossil petroleum. Exploring Botryococcus genus diversity entailed morphological, biochemical and phylogenetic studies. The majority of scientific literature specifies B. braunii as the only species with strains classified in three chemical races (A, B and L) which superpose the phylogenetic clusters built on 18S rDNA sequences. The cohesion of data provided by the three main research directions relies on the integrative analysis of the Botryococcus strains. The present work addresses the diversity of B. braunii race A strains by taking into account the morphology, the hydrocarbon and fatty acid profiles, and the phylogeny of 10 strains, isolated from several Romanian aquatic environments. The newly sequenced B. braunii strains increased the resolution of the analyses and yielded at least two distinct phylogenetic clades within race A cluster. This outcome was sustained by the genetic information coded by the 18S rRNA genes and both sequence-and sequence-structure analysis of ITS2. The Compensatory Base Changes occurrence within the secondary structure of ITS2 and the presence of one intron in the 18S rDNA sequences gave extra credibility to our phylogenetic results. (C) 2016 Elsevier B.V. All rights reserved. |
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article
Molecular Phylogeny Of Botryococcus Braunii Strains (Race A) – An Integrative Approach |
Hegedűs A.; Mocan A.; Barbu-Tudoran L.; Coman C.; Dragoș N. | Algal Research, 2016 | |
AbstractBotryococcus braunii is a green colonial microalga which produces large quantities of liquid hydrocarbons similar to fossil petroleum. Exploring Botryococcus genus diversity entailed morphological, biochemical and phylogenetic studies. The majority of scientific literature specifies B. braunii as the only species with strains classified in three chemical races (A, B and L) which superpose the phylogenetic clusters built on 18S rDNA sequences. The cohesion of data provided by the three main research directions relies on the integrative analysis of the Botryococcus strains. The present work addresses the diversity of B. braunii race A strains by taking into account the morphology, the hydrocarbon and fatty acid profiles, and the phylogeny of 10 strains, isolated from several Romanian aquatic environments. The newly sequenced B. braunii strains increased the resolution of the analyses and yielded at least two distinct phylogenetic clades within race A cluster. This outcome was sustained by the genetic information coded by the 18S rRNA genes and both sequence- and sequence-structure analysis of ITS2. The Compensatory Base Changes occurrence within the secondary structure of ITS2 and the presence of one intron in the 18S rDNA sequences gave extra credibility to our phylogenetic results. © 2016 Elsevier B.V. |
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article
Morphological, Biochemical, And Phylogenetic Assessments Of Eight Botryococcus Terribilis Strains Collected From Freshwaters Of Transylvania |
Hegedus Adriana; Mocan Aurel; Barbu-Tudoran Lucian; Coman Cristian; Druga Bogdan; Sicora Cosmin; Drago Nicolaie | Journal Of Applied Phycology, 2015 | |
AbstractBotryococcus braunii is a green unicellular microalga with a unique potential to produce large quantities of hydrocarbons similar to fossil fuel. Up to now, B. braunii is the most studied species of the Botryococcus genus. The taxonomic affiliation of eight different strains of the genus Botryococcus collected from freshwaters of Transylvania was investigated based on their morphological characteristics and molecular profile using small subunit (SSU) ribosomal RNA (rRNA) genes and internal transcribed spacer 2 (ITS2) sequence-structure analysis. The phylogenetic inference using ITS2 sequence-structure molecular marker, an approach addressed for the first time in the issue of Botryococcus genus phylogeny, generated similar results with the 18S rRNA gene based analysis. In both phylogenetic trees we constructed, the sequences of our strains formed an independent cluster within the B-race clade. Based on the phylogenetic data and the presence of long mucilaginous processes which emerged from the periphery of the colonies, we established the affiliation of our strains to Botryococcus terribilis species. Detailed analyses regarding the growth performances, ultrastructural characteristics, and hydrocarbon and fatty acid profiles were also included in our study. The micrographs obtained in scanning electron, transmission electron, and light microscopies showed a high degree of similarity to other strains affiliated to the B chemical race. Also, gas chromatography-mass spectrometry assay showed for the first time the ability of B. terribilis strains to synthesize C-30-C-32 botryococcenes, which are known to be specific to the B-type Botryococcus strains. |
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