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Adenilat kinaza este o enzimă ubiquitară prezentă atât la procariote cât şi la eucariote. în această lucrare am testat acţiunea inhibitorie a şase 5-ariliden-tiazolidin-4-on-2-tione faţă de adenilat kinaza din Strepto- coccus pneumoniae (A\Ksp) prin metoda colorimetrică cu 2,4-dinitrofenilhidrazonă. Efectul inhibitor al compuşilor de sinteză a fost testat faţă de enzima recombinantă supra-exprimată în E. coli. Compusul C10H6BrNOS2 cu atomul de brom în poziţia -orto a fost cel mai eficace inhibitor, valoarea I50 (concentraţia de inhibitor care determină inhibarea activităţii cu 50%) a fost 0.067mM.

In the present communication, we define the aim and settings of the 12th International Conference on Halophilic Microorganisms, held between 24-28 June at Cluj-Napoca, Romania. A brief chronological list of previous symposia and workshops on halophilic microorganisms held since 1978 is also provided alongside a short description of main benefits and perspectives of investigating the biology and diversity of halophiles. [ABSTRACT FROM AUTHOR]

The origin of the eukaryotic cell and its shared evolutionary history with Archaea are among the hottest topics in modern biology. Recent improvements in cultureindependent genomics and phylogenomic analyses provided compelling evidence in support of the emergence of eukaryotes from within the Archaea. An important step towards revealing the identity and nature of the archaeal ancestor was made following metagenomics-based discovery of the Asgardarchaeota superphylum, a group of uncultivated archaea consisting of Loki-, Thor-, Heimdall- and Odinarchaeia. Their recognition as the closest extant relatives of the eukaryotes has reignited a decades-old debate regarding the topology of the Tree of Life. Moreover, genomic investigations of Asgardarchaeota revealed a plethora of "Eukaryote Signature Proteins" (ESPs), previously thought to be unique to eukaryotes, which may help shed light on the molecular events in early eukaryogenesis. In this work, we briefly review current knowledge about the geographical distribution, phylogeny, ESP content and metabolic capabilities of the highly diverse Asgardarchaeota in an attempt to picture the lifestyle and early evolution of eukaryotes. [ABSTRACT FROM AUTHOR]

Saline aquatic systems include inland and marine-derived lakes, solar salterns, or temporary inland saline ponds. Despite their high salinity, these ecosystems are inhabited by diverse microbial communities driving full biogeochemical cycling of main elements. To date, numerous salt-loving (or 'halophilic') environmental strains with metabolic traits of applicative interest belonging to all Domains of Life (Bacteria, Archaea, Eukarya) have been isolated from saline aquatic systems. The aim of the present work is to briefly review some of the most relevant achievements in the bioprospecting of saline aquatic systems for compounds and metabolic capabilities with potential uses in the environmental, industrial, and food biotechnologies. Additionally, the successful stories of current commercial exploitations of a few halotolerant (e.g., the bacterium Halomonas elongata), halophilic (e.g., the green algae Dunaliella sp.), and haloalkaliphilic microbes (e.g., the sulfur-oxidizing bacteria of genus Thioalkalivibrio sp.) are overviewed. [ABSTRACT FROM AUTHOR]

In the present work, we review the current knowledge on genesis, limnology and biodiversity of salt lakes distributed around the inner contour of Eastern Carpathian arc (Transylvanian Basin, Central Romania). Transylvanian salt lakes formed on ancient halite (NaCl) deposits following natural processes or quarrying activities. Most of these lakes are located in eastern (Sovata area), southern (Ocna Sibiului), and western (Turda-Cojocna) parts of the Transylvanian Basin, have small surfaces (0.1-4 ha), variable depths (2-100 m), are hypersaline (>10%, w/v, total salts, mainly NaCl) and permanently stratified. As consequence of steady salinity/ density gradient, heat entrapment below surface layer (i.e., heliothermy) develops in several transylvanian lakes. The physical and chemical water stratification is mirrored in the partition of plankton diversity. lakes with less saline (2-10% salinity) water layers appear to harbor halotolerant representatives of phyto- (e.g., marine native Picochlorum spp. and Synechococcus spp.), zoo- (e.g., Moina salina), and bacterioplankton (e.g., Actinobacteria, Verrucomicobia), whereas halophilic plankton communities (e.g., green algae Dunaliella sp., brine shrimp Artemia sp., and members of Halobacteria class) dominate in the oxic surface of hypersaline (>10% salinity) lakes. Molecular approaches (e.g., PCR-DGGE, 16s rRNA gene-based clone libraries, and DNA metabarcoding) showed that the O2-depleted bottom brines of deep meromictic transylvanian lakes are inhabited by known extremely halophilic anaerobes (e.g. sulfate-reducing delta-Proteobacteria, fermenting clostridia, methanogenic and polymer-degrading archaea) in addition to representatives of uncultured/unclassified prokaryotic lineages. overall, the plankton communities thriving in saline transylvanian lakes seem to drive full biogeochemical cycling of main elements. However, the trophic interactions (i.e., food web structure and energy flow) as well as impact of human activities and predicted climate changes are yet to be assessed in these unique ecosystems with little or no match to analogous salt lakes worldwide. [ABSTRACT FROM AUTHOR]

Ursu Lake is a large saline, meromictic and heliothermal lake located in the eastern part of the Transylvanian Basin (Sovata, Mureş County, Romania). The investigated lake is characterized by a strong vertical stratification of physical and chemical parameters that indicate a corresponding stratification of biodiversity. Using BIOLOG EcoplateTM method we were able to describe the community-level physiological profile of the microbial population inhabiting the moderately saline epilimnion (5-6% salinity) of Ursu Lake. The metabolization of 31 different carbon sources was monitored in the water samples collected at 0.5 m depth from two different seasons: October 2013 and March 2014. Physicochemical parameters (temperature, salinity, pH, oxidation-reduction potential, and dissolved oxygen) were measured along with the estimation of the total chlorophylls, carotenoids, and prokaryotic cell count. The results revealed a higher rate of C substrate consumption in the water sample collected in spring compared to that found in the autumn sample. This finding is paralleled by the differences observed in some of the chemical parameters (salinity, dissolved oxygen) between the seasons suggesting a time-based modification of the microbial activity. Alphacyclodextrin, glycogen, D-cellobiose, D-mannitol, and N-acetyl-D-glucosamine were the fastest metabolized C sources in both seasons. This is the first report of using BIOLOG Ecoplate™ approach in profiling the microbial activity in a Romanian deep, meromictic and heliothermal salt lake and one of the very few attempts reported to use the BIOLOG system for the characterization of microbial communities in hypersaline ecosystems. [ABSTRACT FROM AUTHOR]

Chemical contamination of fresh and marine water has a strong influence on the metabolic status of aquatic organisms. The expression level and catalytic activity of enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) etc., could be sensitive biomarkers for the oxidative stress induced in aquatic organisms by abnormal levels of biotic and abiotic factors. The present work aimed to study the effect of increasing lead concentration under controlled conditions on the levels of SOD activity in living microinvertebrates and to find the most appropriate class of interstitial invertebrates that respond promptly to the heavy metal contamination. The interstitial water samples were collected at Station Scarisoara on Aries River, during March 2010. The microinvertebrates found have been sorted and identified as belonging to Oligochaeta, Nematoda and Copepoda (Cyclopida) groups. The organisms of each group have been separated and incubated in the presence of lead concentration similar to that determined in the original environment (30 μg Pb/dm3). Biological samples consisting of living microinvertebrates have been analysed for SOD activity at 0 and 24 hours, and after 7 days of incubation, respectively. Our preliminary results suggest a modulation of activity of SOD, by lead ions present in the surroundings of living microinvertebrates tested. [ABSTRACT FROM AUTHOR]

The oxic–anoxic transition zone (OATZ) of freshwater sediments, where opposing gradients exist of reduced iron and sulfide with oxygen, creates a suitable environment for microorganisms that derive energy from the oxidation of iron or sulfide. Gradient microcosms incubated with freshwater sediment showed rapid microbial turnover of sulfide and oxygen compared with sterile systems. Microcosms with FeS as a substrate also showed growth at the OATZ and subsequent dilution series resulted in the isolation of three novel strains, of which strain J10 grows chemolithoautotrophically with reduced sulfur compounds under microaerobic conditions. All three strains are motile spirilla with bipolar flagella, related to the genera Magnetospirillum and Dechlorospirillum within the Alphaproteobacteria. Strain J10 is closely related to Magnetospirillum gryphiswaldense and is the first strain in this genus found to be capable of autotrophic growth. Thiosulfate was oxidized completely to sulfate, with a yield of 4 g protein mol−1 thiosulfate, and autotrophic growth was evidenced by incorporation of 13C derived from bicarbonate into biomass. A putative gene encoding ribulose 1,5-bisphosphate carboxylase/oxygenase type II was identified in strain J10, suggesting that the Calvin–Benson–Bassham cycle is used for autotrophic growth. Analogous genes are also present in other magnetospirilla, and in the autotrophically growing alphaproteobacterium magnetic vibrio MV-1. [ABSTRACT FROM AUTHOR]

Natural nitrogen cycling is at present seriously disturbed by human activities. The main sources of nitrogen pollution are the industrial streams and municipal wastewater. The biotechnological treatment of such streams represents a viable alternative to the classic technologies of reducing the pollutants level released to the water, soil or atmosphere. In the present paper, the current knowledge on anaerobic ammonium oxidation (anammox), a recently described biological process, is discussed in regard to its biotechnological potential in nitrogen removal from wastewater. The process is compared to conventional biological nitrogen removal and the main modes of operation are also given. The paper is concluded with an overview of the state of the art of application on full scale. [ABSTRACT FROM AUTHOR]

In June 2019, the 12th International Conference on Halophilic Microorganisms – Halophiles 2019, was held in Cluj-Napoca, Romania. This thematic issue of FEMS Microbiology Letters contains papers based on lectures and posters presented at the conference. We here provide a short overview of past research on hypersaline environments in Romania and the microorganisms inhabiting them, and briefly present the papers published in this thematic issue. [ABSTRACT FROM AUTHOR]

In this work, we explored the structure of prokaryotic communities inhabiting the sediments of nine lakes with different salinities (from 84 to 344 g L-1) located in Central and South-Eastern Romania. The 16S amplicon sequencing approach combined with geochemical measurements were employed to i) assess local molecular diversity of prokaryotic communities, ii) evaluate the geographical and environmental factors affecting the community composition among sediments of distinct geochemical conditions, and iii) infer key microbial players in the biogeochemical cycling of C, S, and Fe. High relative abundances of 16S rRNA gene reads were assigned to Actinobacteria, Alphaproteobacteria, Bacteroidia, Clostridia, Deltaproteobacteria, Gammaproteobacteria, Mollicutes, and Rhodothermia bacterial classes and to Halobacteria, Thermoplasmata, and Woesearchaeia among the Archaea. Highest richness and diversity were found in sediments containing 96 g L-1 and 300 g L-1 NaCl. Additionally, the analyzed saline sediments appeared to be inhabited by uncultured Bacteria (Gracilibacteria, Marinimicrobia, Omnitrophicaeota, Patescibacteria) and Archaea (Altiarchaeota, Asgardarchaeota, Diapherotrites, Hadesarchaeota) with possible crucial roles in C and S cycling. A microbially-driven Fe cycle could be speculated from the presence of Zetaproteobacteria-affiliated reads in five sediments with different salinities. In conclusion, we provided clues about the microbial diversity and its putative functional capabilities in poorly investigated, saline aquatic habitats. [ABSTRACT FROM AUTHOR]

Toxic levels of heavy metals pose a significant threat on living cells, triggering metabolic strategies that help in adaptation to heavy metal-induced stress. We explored the mechanisms assisting the silver resistance in the extremely halophilic archaeon Halomicrobium mukohataei DSM 12286. The modulatory effects of AgNO3 on the cellular antioxidant systems were assessed by evaluating the malondialdehyde levels, the catalase activity, and the total antioxidant, non-enzymatic capacity. Biosynthesized silver nanoparticles were characterized using UV-VIS spectroscopy, bright-field microscopy, transmission and scanning electron microscopy, energy-dispersive X-ray spectroscopy, dynamic light scattering, and the zeta potential measurement. Additionally, bioinformatic approaches were used to infer putative Cu/Ag-transporters that might mediate the evidenced intracellular accumulation of silver nanoparticles. H. mukohataei was seemingly able to mitigate Ag-induced oxidative stress mainly by using non-enzymatic cellular antioxidants. Additionally, we noted the synthesis of spherical and electrically stable intracellular nanoparticles, with sizes ranging from 20 to 100 nm. It was further speculated that active Ag-resistance in H. mukohataei could be achieved through Ag+ uptake by PIB type ATPases followed by accumulation of silver in its colloidal form. To the best of our knowledge, the present work is the first documentation of intracellular silver accumulation in halophilic Archaea, thus broadening current knowledge on heavy-metal resistance in salt-loving microbes, with implications for their potential uses in biomining or bioremediation strategies. [ABSTRACT FROM AUTHOR]