Search Results (113)

Background: The increasing consumption of psychoactive pharmaceuticals has led to their continuous release into aquatic environments. Methods: This study assessed the ecotoxicological responses, phytoremediation capacity, and ecological risk of seven psychoactive pharmaceuticals—citalopram (CIT), sertraline (SER), fluoxetine (FLU), alprazolam (ALP), clonazepam (CLO), risperidone (RIS), and topiramate (TOP)—using Lemna minor under controlled exposure conditions. Plants were exposed to a concentration gradient, and physiological endpoints, including relative growth rate, chlorophyll content, and maximum photosystem II efficiency (Fv/Fm), were evaluated alongside compound removal and abiotic degradation. Results: Dose–response modeling revealed substantial variability in toxicity, with TOP (EC₅₀ = 74.11 ng L⁻¹), CLO (104.8 ng L⁻¹), and RIS (138.5 ng L⁻¹) exhibiting the highest potency, whereas FLU (1751 ng L⁻¹), CIT (89,941 ng L⁻¹), and ALP (465,351 ng L⁻¹) were less toxic. Relative growth rate was the most sensitive endpoint. Mixture exposure did not result in additional toxicity compared to the most responsive individual compounds. Abiotic degradation was negligible for most compounds (<3%), except for SER (~42%) and FLU (~22%). In contrast, L. minor achieved net removal efficiencies of up to 81%, although reductions occurred under mixed conditions. Probabilistic risk assessment indicated a high ecological risk (msPAFtotal = 1.0), with RIS as the dominant contributor. Full article

Difenoconazole is a triazole fungicide used to ensure sustainable agricultural, although it may also affect the aquatic environment. This study assessed the effects of this fungicide by both an experimental and a computational approach. The experimental assessment involved the acute exposure of Lemna minor to different concentrations of difenoconazole and the determination of main endpoints such as number of fronds and colony, as well as secondary endpoints represented by gravimetric, morphometrical and biochemical parameters. The in silico analysis consisted of the testing of difenoconazole and 14 of its transformation residues (TRs), using three computational tools (admetSAR, ADMETlab and T.E.S.T.) to assess either their toxicological endpoints (EC₅₀, IGC₅₀) or their probability of affecting a range of model aquatic organisms. The results highlighted a concentration-dependent effect of difenoconazole on both main and secondary endpoints. The calculated EC₅₀ value was 2.47 mg/L (data validated by EC₅₀ on Lemna gibba from Pesticides Properties DataBase), which categorizes difenoconazole as moderately toxic in the aquatic environment. The in silico assessment showed that two of the TRs showed lower toxicity, with these having only one aromatic ring compared to the others analyzed. Full article

Heavy metals contaminating the environment is a global concern. Duckweed (Lemna minor) is a promising plant for the phytoremediation and biosorption of metal-contaminated water. Although studies have shown that duckweed can remove multiple metals, there is limited research comparing the efficiency of fresh and dried biomass for wastewater treatment. To evaluate the performance of both forms, fresh and dried duckweed were exposed to metal solutions containing varying concentrations of Cr⁶⁺, Cd²⁺, and Zn²⁺ (5 mg/L Cr⁶⁺ + 1 mg/L Cd²⁺ 10 mg/L Zn²⁺; 10 mg/L Cr⁶⁺ + 5 mg/L Cd²⁺ + 50 mg/L Zn²⁺; or 50 mg/L Cr⁶⁺ + 25 mg/L Cd²⁺ + 250 mg/L Zn²⁺) for a duration of 168 h. Metal uptake in fresh duckweed followed zero-order kinetics for Cr⁶⁺, Cd²⁺, and Zn²⁺ sequestration or Michaelis–Menten kinetics for Cd²⁺ and Zn²⁺ uptake, rather than a first-order model. In contrast, dried duckweed reached equilibrium more rapidly, within 4–48 h, exhibiting pseudo-second-order kinetic and fitting the Langmuir isotherm model. Zn²⁺ reached equilibrium the fastest (4 h), Cd²⁺ required 4–24 h, and Cr⁶⁺ required up to 48 h to reach equilibrium. In general, fresh duckweed uptakes more metals over the 168 h period, depending on the metal type and concentration. However, dried duckweed demonstrated a rapid remediation capability. The findings highlight the complementary potential of applying both fresh and dried duckweed for wastewater treatment. Full article

Global population growth is expected to increase poultry meat demand, intensifying the need for sustainable protein sources. Soybean meal, the primary protein feed for poultry, has negative associations with deforestation and long transport distances. Duckweed has emerged as a possible, more sustainable alternative due to its high growth rate and protein yield. The nutrient digestibility and performance effects of the duckweed species Lemna minor (L. minor) in broiler diets were investigated in two experiments. Experiment 1 determined the ileal digestibility of crude protein, amino acids, phosphorus, and metabolizable energy in L. minor. The digestibility of most amino acids in L. minor ranged from 70% to 96%, with lysine and methionine at 87% and 86%, respectively. At 48%, the digestibility of cysteine was markedly lower than that of the other amino acids. However, the digestibility of P exceeded 90%. The energy values of dry matter were 7.05 MJ AME and 6.13 MJ. Experiment 2 tested the inclusion of L. minor (up to 10%) in isoenergetic and isonitrogenous diets. No significant effects on nutrient digestibility, weight gain, feed intake, or feed conversion ratio were observed. Both experiments demonstrate that L. minor cultivated under controlled conditions is a highly digestible, reliable feed source. Its inclusion in broiler diets is feasible, as it does not impair performance, yet provides amino acid balance whilst ensuring biomass quality. These findings support L. minor as a novel protein alternative and warrant further research on higher inclusion rates. Full article

The growing demand for sustainable protein alternatives has increased interest in underutilized plant biomasses with high nutritional potential. This study investigated the conversion efficiency of alfalfa (Medicago sativa L.) and duckweed (Lemna minor L.) proteins through multienzyme hydrolysis, with the aim of evaluating how carbohydrate–protein matrix interactions influence enzymatic accessibility and apparent protein digestibility. Three biotechnological hydrolysis schemes were applied, involving combinations of α-amylase, amyloglucosidase, protease, pepsin, pancreatin, and bile salts, including an in vitro gastrointestinal digestion simulation. The first hydrolysis scheme demonstrated that starch-rich matrices formed a viscous medium that reduced protease mobility and limited protein cleavage. Improved substrate accessibility was achieved when plant material was pre-treated with amylolytic and proteolytic enzymes, which resulted in a noticeably higher release of free amino acids. Amino acid profiling revealed that this enzymatic sequence was the most effective for disrupting carbohydrate-associated protein fractions in both species. In vitro digestion assays indicated higher apparent protein conversion for duckweed compared to alfalfa under standardized laboratory conditions. Overall, the results confirm that appropriate multienzyme strategies can enhance amino acid liberation from complex plant matrices and highlight duckweed biomass as a promising candidate for sustainable protein valorization. Full article

Artificial water bodies in post-mining landscapes often remain chemically altered and ecologically degraded, yet their ecological risk is frequently underestimated by conventional water quality assessments. Persistent toxicity in mining-impacted waters is a global challenge, as acidity alone often fails to explain the adverse biological effects observed. This study assessed the ecological condition of three artificial ponds in a former gold–antimony mining area (Midões, northern Portugal), using an integrated framework that combined physicochemical and biological (phytoplankton and macroinvertebrates) elements with ecotoxicological assays. Ecotoxicity was evaluated using Lemna minor (growth inhibition) and Daphnia magna (acute toxicity, survival, and feeding rate) under untreated water and pH-adjusted conditions to disentangle acidity-driven effects from other chemical stressors. According to Water Framework Directive metrics, all ponds were classified as having moderate ecological potential, driven by persistent acidic conditions and elevated heavy metal concentrations (e.g., zinc and cadmium). Biological communities showed marked temporal/spatial variability, reflecting physicochemical differences among ponds. Phytoplankton showed summer blooms of cyanobacteria, while macroinvertebrates were generally dominated by tolerant taxa (exhibiting low taxonomic richness/diversity). Ecotoxicological assays showed consistent toxicity across all sampling periods, with high mortality and reduced feeding rates in D. magna and growth inhibition in L. minor. Notably, toxicity often persisted even after pH adjustment, indicating that the observed biological effects were not driven by acidity but were largely attributable to residual metal contamination. These findings highlight the ecological vulnerability of mining-impacted water bodies and underscore the need for management and remediation strategies that address metal removal in addition to pH correction. Full article

The aim of this study was to evaluate the impact of fluoxetine, a widely used selective serotonin reuptake inhibitor, on two aquatic plants: Lemna minor and Spirodela polyrhiza. Additionally, the effect of exogenous serotonin on the level of fluoxetine-induced stress in duckweed will be studied. Increasing presence of antidepressants in surface waters poses ecological risks, and the duckweed species are ideal model organisms for ecotoxicological studies due to their rapid growth and ability to accumulate pollutants. For 14 days, plants were exposed to fluoxetine (0.001–150 mg L⁻¹), followed by a recovery phase in a drug-free medium or a medium supplemented with exogenous serotonin. We analysed morphological/physiological parameters (frond length and area, fresh and dry mass, hydration, stomatal size), the activity of antioxidant enzymes (catalase, ascorbate peroxidase, superoxide dismutase), cell viability, and the level of heat-shock proteins. The plants’ ability to remove fluoxetine from the medium was also assessed. High fluoxetine concentrations (50–150 mg L⁻¹) significantly reduced fresh mass (by 63–98% in L. minor and 56–97% in S. polyrhiza), frond area (by 21–48% in L. minor and 11–25% in S. polyrhiza), and cell viability (by 36–94% in L. minor and 49–94% in S. polyrhiza), and induced oxidative stress. Despite this, both species showed high regeneration potential after the stressor’s removal. Serotonin supplementation did not affect morphology but increased antioxidant enzyme activity, improved cell viability, and elevated heat-shock proteins levels. Crucially, serotonin significantly increased the efficiency of fluoxetine removal. The data can provide a basis for predicting fluoxetine removal efficiency in plants with different levels of endogenous serotonin. L. minor and S. polyrhiza exhibit substantial tolerance to fluoxetine, and antioxidative enzymes are sensitive markers of this stress. Full article

The presence of substantial amounts of heavy metals in the environment can result in various significant ecological issues and human health risks. Currently, bioremediation employing microorganisms is garnering significant interest due to its effectiveness. The present investigation aimed to isolate actinobacterial strains from an Italian mine and to characterise them for heavy metals resistance and plant growth-promoting characteristics. The different samples were processed for DNA extraction and 16S rRNA gene metabarcoding to investigate the bacteria and archaea communities. Cultivable microbiota were isolated and evaluated for heavy metals tolerance and different PGP traits. The most pertinent strains were tested for compatibility, merged into a consortium, and tested on Lemna minor L. Metabarcoding analysis revealed that amplicon sequence variants (ASVs) at the phylum level were mostly assigned to proteobacteria and bacteroidota. Uncultured and unknown taxa were the most prevalent in the samples at the genus level. A total of ten strains were obtained from the culture-dependent approach exhibiting interesting heavy metals tolerance and plant growth-promoting traits. The best strains (MTW 1 and MTW 5) were selected and further characterised by 16S barcoding. These strains were identified as Streptomyces atratus (99.57% identity). An in planta experiment showed that the metal-tolerant consortium MTW 1-5 improved plant physiology by significantly optimising plant growth and tolerance to heavy metals. The experiment conducted provided evidence for the possibility of using actinobacteria as bioaugmentation agents to improve the phytoextraction abilities of L. minor. Full article

This study focuses on biogas production within lab-scale semi-batch bioreactors using agro-industrial wastes and dry biomass of an invasive aquatic species. In particular, the primary objective is to increase the yield of anaerobic digestion processes, with a specific focus on reducing CO₂ emissions associated with the degradation of biomass, by co-digesting different raw biomasses and agro-industrial wastes. In detail, the experiments concerned the pulp of Brewery’s Spent Grain (BSGp), consisting of the residual of Brewery’s Spent Grain after fiber deconstruction with ionic liquids–based treatment, and Lemna minor L. (LM). The two biomasses were studied separately and then co-digested. Co-digestion was carried out using a 1:1 (VS basis) mixture of Lemna minor and Brewery’s Spent Grain pulp. Due to the lack of organic nitrogen, BSGp showed low biogas production if compared with untreated BSG (1.14 × 10⁻³ vs. 1.71 × 10⁻³ Nm³/gVS). Differently, LM has a high nitrogen content and, when digested alone, produced 9.79 × 10⁻⁴ Nm³/gVS. The co-digestion tests allowed us to reach the highest performance: 2.94 × 10⁻³ Nm³/gVS. In terms of bioenergy production, the two biomasses showed high synergy when used in co-digestion. The amount of energy produced was calculated using a lower heating value (LHV) of CH₄ equal to 52 MJ. The results showed that co-digestion yielded 64.9 ± 0.6 MJ/kgVS, followed by BSG (43.3 ± 5.3 MJ/kgVS), BSGp (25.6 ± 0.3 MJ/kgVS), and LM (19.3 ± 1.0 MJ/kgVS). In addition, in terms of CO₂ avoided, the following results were achieved: 0.38–0.40 gCO₂/gVS with BSGp, 0.73–0.8 gCO₂/gVS with LM. Conversely, co-digestion tests allowed for the avoidance of 1.68–1.91 gCO₂/gVS. In conclusion, co-digesting BSGp with Lemna minor yields more methane and less CO₂ per unit processed, providing an effective way to convert readily available waste and biomass into bioenergy. Full article

The expanding development of graphene-based materials (GBMs) requires immediate and balanced environmental assessment balancing two key areas: investigating the risk of graphene oxide toxicity to ecosystems and evaluating GBMs’ potential to act as solutions for challenges like heavy metal stress mitigation. This study analyzed the effects of reduced graphene oxide (rGO) on copper (Cu) and nickel (Ni) toxicity in Lemna minor. Our findings reveal that rGO’s protective effects are metal-specific. L. minor demonstrated significant sensitivity to nickel, but rGO offered no mitigation; growth parameters, pigment content, and nickel accumulation showed no significant improvements with rGO co-exposure compared to Ni-plants. This suggests that rGO does not enhance L. minor’s ability to tolerate or absorb nickel, especially after 14 days (T14). In contrast, rGO showed a partially protective effect against copper toxicity. At T14, the presence of rGO significantly improved plant performance under copper stress, resulting in a 17% increase in biomass, a 19% increase in relative growth rate, and enhanced pigment content, including a 40% increase in chlorophyll when compared to Cu-plants. The protective effect of rGO was directly tied to a 37% reduction in copper accumulation, providing strong evidence that rGO reduces copper’s bioavailability, thereby limiting plant uptake. The divergent effects on Cu and Ni uptake suggest differing affinities of these metals for rGO. Future research, including large-scale experiments with various GBMs and Lemna clones, is crucial to fully assessing their phytoremediation potential. Full article

Antiretrovirals (ARVs) present variable toxicity to aquatic organisms. This study reviewed the literature from the Web of Science, Scopus, and PubMed to evaluate ARV ecotoxicity, focusing on aquatic models. Inclusion criteria were studies using ARVs as test substances with toxicity data on aquatic organisms. Quality assessment followed the CRED method, and environmental risk was evaluated via risk quotients (RQs) using the ERA tool. Efavirenz emerged as the most toxic ARV, with EC50 values of 0.011 mg/L (Chlorococcum infusionum) to 0.034 mg/L (Raphidocelis subcapitata), causing growth inhibition, photosynthesis reduction, and oxidative stress. Tenofovir showed lower toxicity, with EC50 values above 300.0 mg/L (Biomphalaria glabrata) and 111.82 mg/L (Artemia salina). Other ARVs, including Lamivudine and Zidovudine, displayed moderate toxicity (EC50 3.013–5.442 mg/L in microalgae). Main effects observed included oxidative damage, altered enzyme activity (catalase and NADH-cytochrome C oxidoreductase), reduced growth and photosynthesis, and bioaccumulation in aquatic plants like Lemna minor. Efavirenz also showed synergistic toxicity when combined with other ARVs. These findings indicate that ARVs, particularly highly toxic compounds such as Efavirenz, pose significant ecological risks, emphasizing the importance of proper disposal and remediation strategies to protect aquatic ecosystems. Full article

Duckweeds are small, fast-growing aquatic plants with high starch and protein content, making them promising candidates for next-generation plant biomass resources. Despite their importance, little is known about their interactions with microorganisms, particularly plant growth-promoting bacteria (PGPB), which play key roles in enhancing plant productivity. In this study, we report the plant growth-promoting effects of strain LA-C6, a member of the phylum Armatimonadota, isolated from duckweed fronds. Based on 16S rRNA gene analysis, this strain represents a novel genus-level lineage, and is referred to as Fimbriimonadaceae bacterium strain LA-C6. In axenic co-culture experiments, strain LA-C6 promoted duckweed growth, increasing the frond proliferation of four duckweed species (Lemna minor, Lemna aequinoctialis, Spirodela polyrhiza, and Landoltia punctata) by 1.8- to 4.0-fold compared with uninoculated controls. Importantly, three other phylogenetically distinct Armatimonadota species also exhibited significant plant growth-promoting effects on L. minor, increasing frond number by up to 2.3-fold and dry weight by up to 2.4-fold. This finding highlights the broader potential of diverse Armatimonadota members as PGP bacteria. A survey of the IMNGS database showed that strain LA-C6 and other Armatimonadota species are widely distributed across diverse plant-associated environments. Biochemical assays and gene prediction analyses revealed that strain LA-C6 produces indole-3-acetic acid (IAA) as a representative PGP trait, whereas no additional PGP-associated traits were detected. These results suggest that diverse bacterial lineages within the phylum Armatimonadota exert growth-promoting effects on aquatic plants, potentially through yet-to-be-identified mechanisms. Full article

Use of dicamba, an auxin-mimic herbicide, has increased in recent years. Both the effects of dicamba on non-target plants and the determination of a biological model to determine the dicamba ecotoxicity dynamics are important to monitor the correct and safe use of this herbicide. The objectives of this study were to determine the effects of low doses (simulating herbicide drift) and to determine the acute toxicity of dicamba to aquatic bioindicator species (Lemna minor, Pomacea canaliculate, Hyphessobrycon eques, and Danio rerio) and terrestrial non-target plants (Cucumis sativus, Solanum lycopersicum, and Lactuca sativa) in tropical conditions. Measurements of acute toxicity of dicamba at the concentrations that cause 50% of symptoms of injury (LC50) and other biometric variables were performed. Dicamba was virtually non-toxic to all aquatic bioindicator species (LC50 > 118.0 mg L⁻¹), while it was highly toxic to all terrestrial non-target plants (LC50 < 0.5 mg L⁻¹). Severe injury symptoms (70% to 100%) caused by application of low doses of dicamba were found for all non-target terrestrial plants. Severe injury symptoms (70% to 100%) caused by volatilization of dicamba were found only for S. lycopersicum. Since S. lycopersicum was found as the most sensitive non-target plant, showing high injury symptoms caused by dicamba and significant injury from volatilized dicamba, this species is suitable for environmental monitoring of dicamba applications. Full article

The incidence of duckweed (Lemna minor L.) outbreaks in paddy fields has increased in recent years, but how it impacts rice production is still under debate. This study assessed duckweed’s effects on rice yield and quality under different fertilizer regimes: organic fertilizer (OF), chemical fertilizer (CF), a mix (one-third OF and two-thirds CF based on nitrogen content, COF), and no fertilizer (NF) as a control. For each fertilizer regime, two duckweed treatments were applied: duckweed coverage (Duckweed) and no duckweed coverage (Control). A light wet–dry alternate irrigation method was used in the experimental field. Averaged across all fertilizer treatments, duckweed coverage in paddy fields increased grain yield by 8.3%, mainly due to increased panicle density. Duckweed coverage increased chalky grain percentage by 17.0% under NF, but decreased it by 33.7% under CF, with nonsignificant changes under COF and OF conditions. Similar fertilizer-by-duckweed interactions were also found for chalkiness degree, white degree, breakdown and setback values of the starch rapid visco analyzer (RVA) profile, palatability index, and protein and amino acid concentrations. Duckweed coverage decreased protein and amino acid concentrations but improved the taste of cooked rice under NF, while the opposite trend was observed under CF. Duckweed coverage significantly decreased copper and zinc concentrations in milled rice, which may aggravate the “hidden hunger” risk for rice consumers. Full article

Tarragon extracts, especially from Artemisia dracunculus, have shown their potential as natural pesticides and can harm aquatic ecosystems. In addition, waste from tarragon essential oil production can also contribute to aquatic pollution if not properly managed. In this study, a hydrodistillate and a commercial tarragon essential oil were considered to evaluate their effects on aquatic ecosystems. A growth inhibition test was performed using Lemna minor to evaluate the potential ecotoxicity of tarragon extracts, and a biochemical test was performed to investigate the potential effects of the lowest volume of oil, which did not cause any visible impact on this organism. The results showed that the hydrodistillate did not show toxic effects on L. minor, but the essential oil demonstrated potential ecotoxicity, with volumes of 0.5 µL and above leading to percentage reductions in frond numbers of 50% and higher. The biochemical assay revealed no significant differences between the negative control and the lowest volume of oil tested, suggesting the absence of biochemical effects at low exposure levels. The effects of compounds identified at higher concentrations in the tarragon extracts on other aquatic organisms were predicted using the admetSAR3.0 tool, and potential toxicity against numerous aquatic organisms was emphasized, particularly for cis-beta-ocimene, trans-beta-ocimene, and caryophyllene oxide. These findings emphasize the need for careful consideration of both the application dose and disposal practices of tarragon-based products. Full article