Non-steroidal anti-inflammatory drugs (NSAIDs) are increasingly recognized as potential environmental contaminants that may induce toxicity in aquatic ecosystems. This 3-week microcosm experiment explores the acute impacts of NSAIDs, including diclofenac (DCF), ibuprofen (IBU), and acetylsalicylic acid (ASA), on bacterial communities using a wide range of these substances (200–6000 ppm). The results showed that the NSAID-treated microcosms had higher cell count values than control samples, though the diversity of microbial communities decreased. The isolated heterotrophic bacteria mostly belonged to Proteobacteria, particularly Klebsiella. Next-generation sequencing (NGS) revealed that NSAIDs altered the structure of the bacterial community composition, with the proportion of Proteobacteria aligning with the selective cultivation results. Bacteria had higher resistance to IBU/ASA than to DCF. In DCF-treated microcosms, there has been a high reduction of the number of Bacteroidetes, whereas in the microcosms treated with IBU/ASA, they have remained abundant. The numbers of Patescibacteria and Actinobacteria have decreased across all NSAID-treated microcosms. Verrucomicrobia and Planctomycetes have tolerated all NSAIDs, even DCF. Cyanobacteria have also demonstrated tolerance to IBU/ASA treatment in the microcosms. The archaeal community structure was also impacted by the NSAID treatments, with Thaumarchaeota abundant in all microcosms, especially DCF-treated microcosms, while Nanoarchaeota is more typical of IBU/ASA-treated microcosms with lower NSAID concentrations. These results indicate that the presence of NSAIDs in aquatic environments could lead to changes in the composition of microbial communities.

In the present study 12 water samples of five sampling sites (Tatabánya, Dandár, Szentendre, Szent Flórián and Ciprián groundwaters) known as nutrient-depleted aquatic environments were studied using amplicon sequencing (NGS) and cultivation techniques. Diversity indices and cell counts were determined to assess the species richness in relation to the cell counts within the samples, and the oligocarbophile growth capability of the isolated bacteria was tested in microtiter plates. Altogether, 55 bacterial phyla were identified from the samples by amplicon sequencing. The microbial communities of the different sampling times of the same sites did not differ significantly. Patescibacteria and Proteobacteria were present in all samples. Ciprián sample was dominated by Bacteroidetes, while in Dandár sample a high ratio of Chloroflexi was detected. Rokubacteria and WOR-1 dominated Szent Flórián sample and Tatabánya had a high number of Epsilonbacteraeota. Nine archaeal phyla were also detected; the samples were characterized by the presence of unclassified archaea and Nanoarchaeota, among them Woesearchaeia, as the most dominant. Crenarchaeota and Altiarchaeota were detected in high ratios in Dandár water samples. Among Thaumarchaeota the family Nitrosopumilaceae, and orders of Nitrosotaleales and Nitrososphaerales appeared in Szent Flórián and Tatabánya samples. Key organisms of the different biogeochemical cycles were discovered in these nutrient-depleted environments: methanogenic archaea, methanotrophic bacteria, ammonia oxidizer, nitrate reducers, diazotrophs, sulfate reducers, and sulfur oxidizer. Diversity indices and cell counts of the samples show negative correlation in case of bacteria and positive in case of archaea in Ciprián sample. The high diversity indices in Szentendre samples are connected to low cell counts, most probably due to the vulnerability of the groundwaters to the external environment factors which lead to the infiltration of soil microbes and contaminants to the water. The isolated bacteria were affiliated into four phyla, most of them belonging to Proteobacteria (59%) followed by Actinobacteria (21%), Firmicutes (17%) and Verrucomicrobia (1%). The members of the facultative chemolithotrophic genera of Sphingobium, Sphingomonas, Sphingopyxis were characterizing only Szentendre, Szent Flórián and Tatabánya samples. Only 10% of the isolated species showed an obligate oligocarbophile character. From the samples, a high number of novel bacterial taxa were cultivated. As a conclusion, our results confirmed the predominance of unclassified and unknown taxa in subsurface water, pointing to the importance and necessity of further studies to characterize these microbial populations.

The Moroccan coast is characterized by a diversity of climate, reflecting a great richness and diversity of fauna and flora. By this, marine microbiota plays a fundamental role in many biogeochemical processes, environmental modifications, and responses to temperature changes. To date, no exploration by high-throughput techniques has been carried out on the characterization of the Moroccan marine microbiota. The objective of this work is to study the diversity and metabolic functions of MMM from the Moroccan coast (Atlantic and Mediterranean) according to the water source (WS) and the type of climate (CT) using the approach high-throughput sequencing of the 16SrRNA gene. Four water samples of twelve sampling sites from the four major climates along the Moroccan coastline were collected, and prokaryotic DNA was extracted. V4 region of 16S rRNA gene was amplified, and the product PCR was sequenced by Illumina Miseq. The β-diversity and α-diversity indices were determined to assess the species richness and evenness. The obtained results were analyzed by Mothur and R software. A total of twenty-eight Bacterial phyla and twelve Archaea were identified from the samples. Proteobacteria, Bacteroidetes, and Cyanobacteria are the three key bacterial phyla, and the Archaeal phyla identified are: Euryarchaeota, Nanoarchaeaeota, Crenarchaeota, Hydrothermarchaeota, Asgardaeota, Diapherotrites, and Thaumarchaeota in the Moroccan coastline and the four climates studied. The whole phylum are involved in marine biogeochemical cycles, and through their functions they participate in the homeostasis of the ocean in the presence of pollutants or stressful biotic and abiotic factors. In conclusion, the obtained results reported sufficient deepness of sequencing to cover the majority of Archaeal and Bacterial genera in each site. We noticed a strong difference in microbiota diversity, abundance, and taxonomy inter- and intra-climates and water source without significant differences in function. To better explore this diversity, other omic approaches can be applied such as the metagenomic shotgun, and transcriptomic approaches allowing a better characterization of the Moroccan marine microbiota and to understand the mechanisms of its adaptation and its impacts in/on the ecosystem.

In the present study, a 3-week microcosm experiment was conducted to assess the acute effect of arsenic trioxide [As(III)] at various concentrations (2.03, 4.06, 7.61, and 25.38 mM) on the bacterial communities. Water from a drinking water system (DWS) containing 6 µg/L (0.0000881 mM) of arsenic was used as a basis for microcosm experiments. Tolerance for As(III) of selectively isolated bacteria was checked based on optical density (OD) measurements which revealed As tolerance of Acidovorax facilis and Pseudomonas extremaustralis strains even at 25.38 mM of As(III). Compared to the control samples, the cell count values of the treated microcosms (DAS1_1, DAS2_1, DAS3_1 and DAS1_2, DAS2_2, DAS3_2) were higher by at least one or two orders of magnitude, even though, diversity indices, calculated from the NGS analysis, decreased. Results of NGS have shown that the structure of the bacterial community has changed as an effect of arsenic: representatives of Planctomycetes (3–6%) decreased while there was a proportional increase in the abundance of Proteobacteria (48–93%). Actinobacteria (2–8%), Bacteroidetes (4–7%), Patescibacteria (3–10%) and Verrucomicrobia (2–4%) were also abundant in the As(III)-treated microcosms. Phyla that contributes to less than 1% of the samples have disappeared already at 2.03 mM of As(III). The most frequent Archaea belonged to Nanoarchaeota (Woesearchaeia) (22–57%) and Thaumarchaeota (Nitrosopumilaceae) (9–40%) in both the control samples and microcosms with 2.03–23.38 mM of As(III). The cell structure of tested bacteria showed partial destruction after As(III) exposure. The ecotoxicological test revealed a cytotoxic effect above 6.67 mM concentration of As(III), genotoxicity could not be proven. Even though, microbes in our microcosms can be characterized by As(III) resistance and show measurable reactions to high As(III) concentrations, low concentrations of arsenic also trigger changes in the composition and diversity indices of the microbial communities. It is possible to cultivate arsenic tolerant microorganisms utilizing As(III) up to 25.38 mM to use them in bioremediation procedures contributing to water-purification processes.

The use of nanoscale materials has expanded rapidly in recent decades, with titanium dioxide (TiO₂) nanoparticles among the most widely produced. Their increasing environmental release raises concerns about ecosystem-level effects. A key mechanism of toxicity is the generation of reactive oxygen species (ROS), although these effects strongly depend on particle properties, including crystalline form, size, morphology, surface characteristics, and exposure conditions. Here, we assessed and compared the ecological impacts of anatase and rutile TiO₂ nanoparticles across prokaryotic and eukaryotic systems, including aquatic microbial communities, microbial cultures, plant bioassays (Sinapis alba, Triticum aestivum), the SOS Chromotest, and zebrafish (Danio rerio) assays. Nano-TiO₂ exposure markedly restructured freshwater microbial communities by suppressing sensitive taxa (e.g., Actinomycetota, Flavobacterium, and Limnohabitans) while enriching more tolerant genera such as Pseudomonas, Sediminibacterium, Haliscomenobacter, and Hydrogenophaga. These shifts likely reflect differences in cell-envelope structure, biofilm formation, and antioxidant capacity. The two investigated TiO₂ nanoparticle types showed distinct biological effects: rutile was associated with more pronounced microbial community shifts and bacterial cell damage, whereas anatase caused stronger responses in plant assays, particularly by impairing hypocotyl growth and plant water balance. Besides the limited acute genotoxicity revealed by the SOS Chromotest, TiO₂ nanoparticles did not significantly affect survival or final larval body length in the zebrafish embryo assay under the tested conditions; however, the hatching delay observed at the highest concentration indicated a sublethal developmental effect. Overall, our results show that TiO₂ nanoparticle toxicity cannot be generalized across biological systems and suggest that biological responses depend on the combined influence of particle characteristics and organism-specific structural and physiological traits.