Desmodesmus Subspicatus Research Articles

Toxicity of iron-doped graphene Oxide: Towards eco-friendly carbon-based nanomaterials

Incorporating iron nanoparticles into graphene oxide (GO) may enhance its potential for use in various applications. However, alterations to the GO structure could pose a risk to environmental organisms and should therefore be fully understood before their further use. In this paper, we prepared iron-doped graphene oxide from pure graphene oxide and two different iron sources with iron in two different oxidation states. Prepared samples were characterized in detail by SEM, EDS, XRF, Raman spectroscopy, XPS, and TEM. In the next step, these samples were subjected to ecotoxicological evaluation in three model organisms: mustard Sinapis alba, freshwater algae Desmodesmus subspicatus, and saltwater crustaceans Artemia salina. Our results showed a stimulatory effect of iron-doped GO on S. alba seeds and a modest degree of growth inhibition for D. subspicatus when compared to pure GO at a concentration of 100 mg/L. In the case of A. salina, mortality was observed at a concentration of 10 mg/L for all tested nanoparticles. However, the iron-doped nanoparticles exhibited a more than twofold decrease in mortality. Our findings suggest that iron-doped GO have a reduced toxicity compared to pure GO, but further research is necessary to enhance the understanding of their behaviour in the environment.

Cement pastes containing air entraining agent release the biocide octylisothiazolinone posing ecotoxicological effects

We investigated whether cement pastes are a possible source of ecotoxicologically potent substances. For this purpose, leaching according to DIN EN 16637-2 was performed on portland cement pastes as well as blast furnace slag cement with and without an air entraining agent (AEA). The AEA, consisting of wood rosin and resin, contained the stabiliser drometrizole and the biocide octylisothiazolinone (OIT), which was confirmed by our non-target screening (NTS). Our ecotoxicological studies (Daphnia magna, Aliivibrio fischeri and Desmodesmus subspicatus) of the pure cement eluates showed no effects at all. In these samples, it was possible to attribute up to 85 % of the dissolved organic carbon (DOC) to acetate, formate and diethylene glycol (DiEG). Eluates from cement pastes with AEA contained up to 70 μg/L octylisothiazolinone (OIT), and no drometrizole was found. Around 90 % of the total OIT release happened within the first 6 h. It was possible to attribute the observed ecotoxicological effects mainly to the OIT concentrations. Additional leaching with elevated sulphate concentrations (800 mg/L) did not influence the release of DOC and OIT or increase the ecotoxicological effects. As a consequence, we advise curing the cement paste for 24 h prior to use, as this largely avoids the release of OIT and the observed ecotoxicological effects.

Towards sustainable biocontrol: inhibition of soil borne fungi by microalgae from harsh environments.

Using microorganisms as biocontrol agents against soilborne plant pathogens is a promising alternative to chemical pesticides. However, only some biocontrol agents have proven effective under field conditions. This study explores the potential of highly resilient microalgae isolated from harsh environments, such as Biological Soil Crusts and agricultural fields in semi-arid regions, as a novel and sustainable approach to biocontrol. Fifty-nine microalgal strains, including thirteen cyanobacteria and forty-six green algae, were isolated and identified. Dual-culture plate assays and toxicity tests of microalgal growth media were conducted to evaluate the antifungal activity of the isolates against eight representative soilborne pathogens. The results showed that many microalgae strains exhibited significant inhibitory effects on the growth of specific fungal pathogens, although the activity varied among different microalgal strains and pathogen species. Some strains even promoted the growth of certain fungi. The lack of a clear pattern in the antifungal activity highlights the complexity and specificity of the interactions between microalgae and soilborne pathogens. An "Inhibition Effectiveness" metric was developed to quantify biocontrol potential based on fungal growth inhibition. The green algal genus Desmodesmus, particularly Desmodesmus subspicatus isolates, showed higher antifungal efficacy than other genera. While the inhibitory mechanisms remain unclear, the results demonstrate the promising biocontrol capabilities of microalgae from extreme environments like BSCs. Further research could unlock novel opportunities for sustainable disease management by harnessing specific microalgal strains or synergistic strain combinations targeting soilborne pathogens.

Phycoremediation of As(III) and Cr(VI) by Desmodesmus subspicatus: Impact on growth and biomolecules (carbohydrate, protein, chlorophyll and lipid) - A dual mode investigation.

Microalgae are under research focus for the simultaneous production of biomolecules (e.g., carbohydrates, proteins, pigments and lipids) and bioremediation of toxic substances from wastewater. The current study explores the capability of indigenously isolated microalgae (Desmodesmus subspicatus) for the phycoremediation of As(III) and Cr(VI). Variation of biomolecules (carbohydrate, protein, lipid and chlorophyll) was investigated during phycoremediation. D. subspicatus survived up to the toxicity level of 10mg/L for As(III) and 0.8mg/L for Cr(VI). A 70% decline in carbohydrate accumulation was observed at 10mg/L of As(III). An increased content of proteins (+ 28%) and lipids (+ 32%) within the cells was observed while growing in 0.5 and 0.2mg/L of As(III) and Cr(VI) respectively. A decrease in carbohydrate accumulation was noted with increasing Cr(VI) concentration, and the lowest (- 44%) was recorded at 0.8mg/L Cr(VI). D. subspicatus showed an excellent maximum removal efficiency for Cr(VI) and As(III) as 77% and 90% respectively.

Bioremediation potential of microalgae for copper ion from wastewater and its impact on growth and biochemical contents: equilibrium isotherm studies

The use of microalgae to remediate heavy metal-contaminated wastewater has attracted more and more interest. In this investigation, the green microalgae Chloroidium ellipsoideum and Desmodesmus subspicatus were used to study copper uptake from nutrient media and its effect on algal growth and metabolism. The growth of C. ellipsoideum and D. subspicatus generally decreased with increasing copper concentrations. There was a decrease in the carbohydrate content of C. ellipsoideum, but an increase was observed in D. subspicatus by treatment with various copper concentrations. Low concentrations of copper helped to increase the protein content of C. ellipsoideum, but a decline in protein content was reported for D. subspicatus. By increasing the copper concentrations, an increase in the free amino acids and a decrease in the total lipid content of C. ellipsoideum and D. subspicatus were recorded. At 0.1 mgl–1 copper concentration, pH of 6.8, and algal dose of 1 g L−1, the maximum biosorption capacity of C. ellipsoideum was 0.398 mg g−1, corresponding to the maximum reduction of 68.66% of Cu2+, and 0.396 mg/g for D. subspicatus, corresponding to the maximum reduction of 59.52%. The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models were applied to describe the isothermal biosorption of Cu2+ ions in studied algae. The Dubinin–Radushkevich model indicated that the copper biosorption mechanism was physical in nature. Cu2+ has a greater affinity for D. subspicatus than C. ellipsoideum, suggesting that C. ellipsoideum was relatively more resistant to Cu2+ toxicity than D. subspicatus. Moreover, FT-IR analysis revealed that carboxyl, amide, amino, carbonyl, hydroxyl, methyl and alkyl groups were the key groups responsible for the biosorption process. Therefore, D. subspicatus and C. ellipsoideum are efficient biosorbents for Cu2+ and can be used as biosorbents for heavy metals removal from wastewater.

Oxidative stress signatures and lipid accretion in Desmodesmus subspicatus under in vitro drought stress simulation

Oxidative stress signatures and lipid accretion in Desmodesmus subspicatus under in vitro drought stress simulation

A Chronic Aquatic Hazard Assessment for the Perfume Raw Material Octahydro-tetramethyl-naphthalenyl-ethanone.

Octahydro-tetramethyl-naphthalenyl-ethanone (OTNE) is a high-production volume fragrance material used in various down-the-drain consumer products. To assess aquatic risk, the Research Institute for Fragrance Materials (RIFM) uses a tiered data-driven framework to determine a risk characterization ratio, where the ratio of the predicted-environmental concentration to the predicted-no-effect concentration (PNEC) of <1 indicates an acceptable level of risk. Owing to its high production volume and the conservative nature of the RIFM framework, RIFM identified the need to utilize a species sensitivity distribution (SSD) approach to reduce the PNEC uncertainty for OTNE. Adding to the existing Daphnia magna, Danio rerio, and Desmodesmus subspicatus chronic studies, eight new chronic toxicity studies were conducted on the following species: Navicula pelliculosa, Chironomus riparius, Lemna gibba, Ceriodaphnia dubia, Hyalella azteca, Pimephales promelas, Anabaena flos-aquae, and Daphnia pulex. All toxicity data were summarized as chronic 10% effect concentration estimates using the most sensitive biological response. Daphnia magna was the most sensitive (0.032 mg/L), and D. subspicatus was the least sensitive (>2.6 mg/L, the OTNE solubility limit). The 5th percentile hazardous concentration (HC5) derived from the cumulative probability distribution of the chronic toxicity values for the 11 species was determined to be 0.0498 mg/L (95% confidence interval 0.0097-0.1159 mg/L). A series of "leave-one-out" and "add-one-in" simulations indicated the SSD was stable and robust. Add-one-in simulations determined that the probability of finding a species sensitive enough to lower the HC5 two- or threefold was 1/504 and 1/15,300, respectively. Given the high statistical confidence in this robust SSD, an additional application factor protection is likely not necessary. Nevertheless, to further ensure the protection of the environment, an application factor of 2 to the HC5, resulting in a PNEC of 0.0249 mg/L, is recommended. When combined with environmental exposure information, the overall hazard assessment is suitable for a probabilistic environmental risk assessment. Environ Toxicol Chem 2024;43:1378-1389. © 2024 SETAC.

Study of spectral lines behaviour with a double pulse 1064–1064 nm laser-induced breakdown spectroscopy system at the direct analysis of algae on the filter

The nickel and zinc contamination of algae on a cellulose filter was studied with double pulse 1064–1064 nm laser-induced breakdown spectroscopy (LIBS). Samples of the green alga Desmodesmus subspicatus were contaminated with zinc and nickel. The surface concentrations on the filter calculated from the reference Inductively Coupled Plasma Mass Spectrometry analysis were 25 and 64 ng cm−2 for nickel and zinc respectively. The algae are resting on the filter after drying and a double adhesive tape was used to fix the sample on the microscopic glass. During optimization method a compromise of 23–30 mJ pulse energies were set for maintaining a detectable or highest signal intensity of the analyte and not destroying the filter. Best conditions for maximum analyte signal and minimum deviation between the spectral behaviour of the analyte and the compared line of Na I, K I, Mg I, Mg II, Mn I, Mn II, Ca I, Ca II, and C I was 700 ns gate delay and 0 s interpulse delay. The deviation was rather more influenced with the signal-to-noise ratio of the analyte line than the closeness of the upper-level energies of the compared lines. The filter without algae showed systematically lower electron number density and total emissivity by units of percents than the filter with algae.

Occurrence and distribution of azole antifungal agents in eight urban Romanian waste water treatment plants

Azole compounds are utilized to combat fungal infections in plants to protect them and also used for treating mycosis in humans. The LC-MS/MS method is a technique that combines liquid chromatography with tandem mass spectrometry for analysis of twelve azole compounds from wastewater (influent, effluent) and sewage sludge. The compounds were isolated from waste water using automatic extraction in the solid phase. Sludge samples were dried by lyophilization, after which they were subjected to ultrasound extraction with methanol. The quantification limits ranged from 0.3 ng/L (clotrimazole-CLO and prochloraz-PRO) to 1.5 ng/L (tetraconazole-TEB and penconazole-PEN), for wastewater samples and for sewage sludge, the LOQs ranged from 0.1 ng/g to 0.6 ng/g. High concentrations of climbazole-CLI (207–391 ng/L), tebuconazole (92–424 ng/L), and clotrimazole (6.9–93-ng/L) were observed in influent samples of the 8 urban wastewater treatment plants, followed by fluconazole (49.3–76.8 ng/L), and prochloraz (7.3–72 ng/L). The ∑Azoles had a maximum of 676 ng/L in the Galati effluent, followed by the Bucharest station 357 ng/L, and 345 ng/L in the Braila effluent. The highest value of the daily mass loading (input) level was observed for climbazole, 265 mg/day/1000 in Iasi station, followed by tebuconazole, 238 mg/day/1000 people in the Bucharest station, and 203 mg/day/1000 people for climbazole in the Targoviste station. The daily mass emission presented values between 0.7 and 247 mg/day/1000 people. The highest emissions were observed for climbazole, 247 mg/day/1000 people in Braila station; 174 mg/day/1000 people in the Iasi station and 129 mg/day/1000 people in the Bucharest station. The concentrations of climbazole detected in the effluent can present a high risk for the plants Lemna minor and Navicula pelliculosa. Clotrimazole may present a high risk to the plant Desmodesmus subspicatus and to the invertebrate Daphnia magna. PRO may present high risk to the invertebrate Mysidopsis Bahia.

A novel system for assessing paraquat toxicity using Desmodesmus maximus as a potential bio-indicator and deep learning-based approach

Microalgae play a crucial role as environmental indicators, offering valuable insights into ecosystem health and aiding in the assessment of water source contamination by toxins. In recent times, the presence of paraquat in water sources has become a grave concern due to its high toxicity and persistence. The detection of paraquat in natural water is of paramount importance for safeguarding water quality and public safety. Microalgae are invaluable bio-indicators for pollutant detection, but using small-sized microalgae according to OECD guidelines may not suit toxicity field combined with deep learning due to limitations. In this regard, this study proposes the use of Desmodesmus maximus as a potential bio-indicator, known for its larger cell size, surpassing Desmodesmus subspicatus, the reference strain specified by OECD guidelines. Exposure of D. maximus to 2 mg/L paraquat resulted in significant internal damage and loss of chlorophyll content, with a determined 72 h-EC50 of 0.25 mg/L. Accurate microalgae recognition typically requires time-consuming and inaccessible expert analysis. Therefore, this study explores deep learning techniques to enhance the efficiency and accuracy of microalgae toxicity testing. Deep convolutional neural networks (D-CNNs), including RetinaNet, YOLOv5, EfficientDet, and Faster R-CNN models, are compared for microalgae detection and differentiation. The analysis demonstrates the superiority of the Faster R-CNN model, achieving a remarkable mAP@0.5 value of 0.98 in multiclass conditions for identifying normal, empty, and toxified colonies. These findings underscore the considerable potential of deep learning techniques in advancing microalgae toxicity testing, thereby facilitating enhanced accessibility and cost-effectiveness in monitoring the environmental impact on water resources.

Growth of microalgae and cyanobacteria consortium in a photobioreactor treating liquid anaerobic digestate from vegetable waste

This research examines the biological treatment of undiluted vegetable waste digestate conducted in a bubble column photobioreactor. Initially, the bioreactor containing 3N-BBM medium was inoculated with Microglena sp., Tetradesmus obliquus, and Desmodesmus subspicatus mixture with a density of 1.0 × 104 cells/mL and the consortium was cultivated for 30 days. Then, the bioreactor was semi-continuously fed with liquid digestate with hydraulic retention time (HRT) of 30 days, and the treatment process was continued for the next 15 weeks. The change in the microalgal and cyanobacterial species domination was measured in regular intervals using cell counting with droplet method on a microscope slide. At the end of the experiment, Desmonostoc sp. cyanobacteria (identified with 16S ribosomal RNA genetical analysis) as well as Tetradesmus obliquus green algae along with Rhodanobacteraceae and Planococcaceae bacteria (determined with V3–V4 16sRNA metagenomic studies) dominated the microbial community in the photobioreactor. The experiment demonstrated high treatment efficiency, since nitrogen and soluble COD were removed by 89.3 ± 0.5% and 91.2 ± 1.6%, respectively, whereas for phosphates, 72.8 ± 2.1% removal rate was achieved.

Investigation of toxic effects of BPA and BPA analogues (BPS and BPAF) on Spirulina sp., Desmodesmus subspicatus and Chlorella vulgaris

Bisphenols (BPs) are produced for many applications for used in industry. BPs have been found all part of aquatic environments such as sediment and surface water that is poses a risk to the aquatic ecosystem. Restricting the use of BPA, environmental concentrations of bisphenol S, and bisphenol AF begin to increase. The present study aims to indicate that toxicity BPA and BPA analogues (BPS and BPAF) by algal growth inhibition test for the green algae Chlorella vulgaris, Spirulina sp., Desmodesmus subspicatus. In this way, result of this study present the nominal effective concentrations of BPA analogues and the suitability of the species for use as a biomarker in ecotoxicology tests. IC50 values (growth rate inhibition by 50%, respectively) for three toxicants were determined separately. Results of this study showed the effects of these chemicals on photosynthesis (primer production). The result of algal growth inhibition test showed that BPAF (72h EC50 3.80 mg/L) was found to be more toxic than BPS (3d EC50 6.31 m L-1) for Spirulina sp. BPS (3d EC50 2.43 mg/L) showed the most toxic effect on the growth of C. vulgaris, followed by BPAF with 3d EC50 3.32 mg/L. BPS (3d EC50 0.88 mg/L) and BPAF (3d EC50 6.48 mg/L) were found to be toxic for D. subspicatus, respectively, from highest to lowest toxicity. These results indicate that bisphenol analogues are hazardous to primer production. Therefore, it is necessary to study their combined effects as well as to study how they act individually.

Microplastics: toxicity and Bioacumulation at the first trophic levels of the food chain

Microplastics are dispersed in nature in all planetary compartments, and can be found in the most remote places of the Ecosystem. They are currently indicated as markers of the Anthropocene, a geological era caused by human changes on the globe. Even though it is found in all environmental compartments, there are still gaps in scientific knowledge about its real impact on living cells and their dynamics, including in the human organism. Therefore, the objective of the study is to use an internationally standardized and standardized method in representative organisms of the ecosystem, thus using the acute and chronic ecotoxicity test with the microcrustacean Daphnia magna and for the algae Desmodesmus subspicatus, respectively, against polyethylene microspheres, a thermoplastic widely used as an exfoliation product and applied in various cosmetics and hygiene materials. They were tested in neonates according to the reference standards, but 30-day-old adult organisms were also exposed. The results obtained, for the crustaceans, show the Effective Concentration that causes effect in 50% of the organisms (EC50%), with 95% confidence of 0.07 g/L and a DSC – Observed effect concentration of 0.025 g/L for neonates. For the adult specimens, 0.025 g/L of EC50 and 0.0025 g/L of DSC were found, showing that the pups are 10x more resistant to plasticizers compared to the adults. For the algae test, the results showed a DSC of 0.05 g/L, inhibiting 20.12% of algae growth compared to the control. In the optical microscope of the crustaceans after exposure, it showed bioaccumulation of the polyethylene microsphere in the carapace and digestive tract of the bioindicator, showing that the impact of microplastics begins in the first trophic levels of the food chain.

Grazing inhibition in Daphnia and Bosmina by colony formation of Desmodesmus subspicatus triggered by sodium octyl sulfate.

There are growing concerns that several aquatic contaminants can indirectly alter biological interactions by inhibiting the adaptive phenotypic plasticity of organisms, even at nonlethal concentrations. In Scenedesmaceae, a family of green algae, many chemicals interfere with defensive colony formation against grazers (i.e., through induced or limited coloniality). Although several studies have demonstrated that the effects of coloniality can limit the feeding capacity of Daphnia spp., grazing inhibition in other zooplankton species is not well understood. In this study, we examined the influence of sodium octyl sulfate (SOS) on the growth and morphology of Desmodesmus subspicatus and on the feeding rates of three cladoceran species (Daphnia galeata, Bosmina longirostris, and Bosmina fatalis) feeding on SOS-induced colonies under factorial conditions of different food levels and grazer ages. SOS remarkably induced colony formation with no observed effect on growth in D. subspicatus. D. galeata and B. fatalis showed a remarkable reduction in feeding rates when they fed on colonial D. subspicatus, whereas no significant effect of the prey morphotype was found on the feeding rates of B. longirostris. Microscopic observations of algal morphology after being grazed showed that each species can consume colonial prey depending on food level and age. Comparisons of the inhibition ratio of feeding among the three cladocerans revealed that Daphnia was more sensitive to prey coloniality compared with Bosmina. Our findings provide specific insights into the effects of chemically interfered colony formation on population dynamics and community structures.

Biotechnological investigation of Pediastrum boryanum and Desmodesmus subspicatus microalgae species for a potential application in bioenergy

The production of photosynthetic microalgae is a promising ecological advantage for obtaining carbon credits. This paper addresses cultivation and preparation, growth analysis, physicochemical characterization (X-ray diffraction-XRD, Fourier transform infrared-FTIR, scanning electron microscopy-SEM, and energy dispersive spectroscopy-EDS), and thermal behavior (thermogravimetry-TG, derivative thermogravimetry-DTG, and differential scanning calorimetry-DSC) of two microalgae, namely Pediastrum boryanum-PB (CH007) and Desmodesmus subspicatus-DS (AEE431E) for a potential application as an energy resource. Regarding the former, the literature reports no specific study on the species, which shows high lipid productivity and fast growth. A synthetic culture medium (Walter culture-WC) was subjected to variations in pH, luminosity, and maximum growth reached in 12 and 13 days for PB and DS, respectively. TG/DTG curves identified the main thermal degradation stages, i.e., dehydration (DS (24.68–158.68 °C) and PB (20.06–116.18 °C)), devolatilization (DS (166.34–543.00 °C) and PB (128.22–493.93 °C)), and gasification or carbonization (DS (>550 °C) and PB (>500 °C)), and DSC curves revealed two endothermic events, an exothermic one for DS, and only one endothermic event and an exothermic one for PB. XRD patterns showed a cellulose crystallinity index (CI) for DS (22.54 %) and PB (28.82 %), confirming the predominance of amorphous regions. SEM images detected external epidermis for DS and some interconnected pores for PB. The FTIR spectra identified functional groups (lipids, proteins, and carbohydrates) and CO, CO, OH, CH, and C-O-C linkages, and EDS and ICP-OES identified the main organic, inorganic, and metallic elements. The microalgae species displayed characteristics similar to those of the other biomasses in the bioenergy industry, enabling their use in thermoconversion processes for biofuel production and considering some socioenvironmental aspects.

Study of bioaccumulation of Cr, Ni and Zn by the green alga Desmodesmus subspicatus and assessment of the toxic effect of selected elements and their mixtures on algae cells

Toxicity assessment of K2Cr2O7, ZnCl2 and NiCl2.6H2O focusing on the green unicellular alga Desmodesmus subspicatus showed that Ni was the most toxic (EC50 = 0.121 mg L−1), followed by Cr (EC50 = 0.357 mg L−1) and Zn (EC50 = 0.968 mg L−1). The alga was exposed to solutions of the individual metals and their mixtures (Zn + Ni, Zn + Ni + Cr). After 48, 72 and 96 h of exposure, the accumulation of Zn, Ni and Cr in algal cells was assessed. Moreover, the change in toxicity of the metals, the concentration of selected biogenic elements (Ca, Na, Mg, S, K, P, Mn) in algal cells and the rate of metal removal from the solutions were also analysed. In the case of single-metal solutions, for Zn and Cr, the toxicity and accumulation in algal cells decreased over the 96 h of the experiment, whereas for Ni as well as for the binary and ternary mixtures the toxicity and accumulation increased. Significant correlations between the amount of metals accumulated in the cells and the inhibition of growth rates were observed. The content of selected biogenic elements in algal cells decreased over time in all treatments with added metals as well as in the control group, and after 96 h was higher in all treatments with addition of Ni compared to the control group and single-metal solutions of Zn and Cr. The highest removal of the metal from the solution occurred in the case of the single metal solution of Zn, where 83.4% of Zn was removed from the solution in 96 h.

Enhancement for the synthesis of bio-energy molecules (carbohydrates and lipids) in Desmodesmus subspicatus: experiments and optimization techniques

Microalgae are regarded as renewable resources of energy, foods and high-valued compounds using a biorefinery approach. In the present study, we explored isolated microalgae (Desmodesmus subspicatus) for the production of bio-energy molecules (carbohydrate and lipid). Optimizations of media (BG-11) components have been made using the Taguchi orthogonal array (TOA) technique to maximize biomass, carbohydrate and lipid production. Optimized results showed that biomass, carbohydrates and lipid productivity increased by 1.3 times at optimal combinations of media components than standard BG-11 media. Further, the influence of various carbon and nitrogen sources as nutritional supplement with optimum media composition under different light intensities was investigated for productivity of carbohydrate and lipid. Results demonstrated that 1.5 times higher productivity of carbohydrate and lipids were achieved in the presence optimum BG-11 under a broad range of light intensities (84–504 µmol m−2 s−1). Among different nitrogen sources, glycine was found to give higher productivity (1.5 times) followed by urea. Use of the cellulose as a carbon source in the media significantly increases biomass (2.4 times), carbohydrates (2.3 times) and lipids (2.3 times) productivity. Investigations revealed that cultivating Desmodesmus subspicatus under optimum culture conditions has the potential for large-scale bio-ethanol and bio-diesel production.

A test battery approach for ecotoxicological evaluation of disinfectants prepared on the basis of sodium hypochlorite

Abstract The research is related to the assessment of the overall sensitivity and applicability of many bioassays representing different trophic levels for the preliminary ecotoxicological testing of commercial disinfectants marked as SA (SAVO, Bochemie a.s., Czech Republic) and DoAm (Dom Amor, BOOS – Biologické substancie, Slovak Republic). Disinfectants were prepared based on sodium hypochlorite (NaOCl). SA contains only NaOCl while earthworm enzymes enrich DoAm. In both commercial products, the NaOCl content did not exceed 5%; pure NaOCl was used as a 10% solution as well. For bioassay, water organisms (Vibrio fischeri, Desmodesmus subspicatus, Daphnia magna and Tubifex tubifex) situated in various trophic levels were used. All the tests were confirmed as suitable for the determination of chlorine’s adverse effects. Because the organisms’ reactions to the tested disinfectants varied, they can be arranged in the following rank order of sensitivity: V. fischeri ≥ D. subspicatus &gt;&gt; D. magna &gt;&gt; T. tubifex. The toxicity of the tested substances (NaOCl, SA, DoAm) depends on the length of exposure, the species of the organism and FAC (free available chlorine) content. The effective concentrations of the tested products ranged from 0.13 to 8.18 μL L–1, i.e., 0.014 to 0.26 mg L–1 of FAC. However, in the tests with T. tubifex and V. fischeri the toxic effect of NaOCl was the weakest; the tests with other two organisms confirmed this compound as the most toxic. Only for T. tubifex (96 hrs) did SA have a more adverse effect than DoAm.

The Use of Aquatic Macrophytes as a Nature-Based Solution to Prevent Ciprofloxacin Deleterious Effects on Microalgae

Macrophytes have demonstrated excellent potential for the removal of pharmaceuticals from water. However, there is a lack of studies on the ecotoxicity of water after phytoremediation. In this study, we evaluated the toxicity of ciprofloxacin (Cipro) on the microalgae cells of Desmodesmus subspicatus exposed to water contaminated with Cipro and previously treated by Salvinia molesta or Egeria densa for 96 h. Microalgae exposed to Cipro (1, 10, and 100 µg L−1) in untreated water showed decreased rates of growth, respiration, and photosynthesis, and increased oxidative status (hydrogen peroxide concentration) and oxidative damages (lipid peroxidation). S. molesta exhibited a greater phytoremediation capacity than E. densa, reducing Cipro concentrations in water to below its toxic threshold to D. subspicatus (2.44 µg L−1), even when the antimicrobial was present at a concentration of 10 µg L−1. During the water treatment, neither S. molesta nor E. densa released compounds that had a toxic effect on D. subspicatus. This work demonstrates the novelty of using S. molesta and E. densa as a nature-based solution to remove Cipro from contaminated water. For the first time, we provide evidence of the ecotoxicological safety of this approach, as it prevents the deleterious effects of Cipro on photosynthetic microorganisms and helps to avoid the development of antimicrobial resistance.

A new concept for the ecotoxicological assessment of plastics under consideration of aging processes

AbstractMicroplastics are widely distributed in aquatic and terrestrial environments, but up to now less is known about (eco)toxicological impacts under realistic conditions. Research so far has focused mainly on impacts on organisms by fresh, single‐origin plastic fragments or beads. However, plastics found in the environment are complex in composition, this means different polymer types and sources, with and without additives and in all stages of age, and therefore, in a more or less advanced stage of degradation. For oxidized degradation products that might be released from plastic materials during aging, there is a lack of information on potentially adverse effects on aquatic biota. The latter is of particular interest as oxidized degradation products might become more water soluble due to higher polarity and are more bioavailable, therefore. The present study focused on plastic leachates of polystyrene (PS) and polylactic acid (PLA), which were derived from alternating stress by hydrolysis and ultraviolet (UV) radiation—representing a realistic scenario in the environment. Test specimens of PS, PLA, or a PLA/PS layer (each 50%) were alternately exposed to UV radiation for 5 days followed by hydrolysis for 2 days, for several weeks alternating. Ecotoxicological effects of the storage water (artificial freshwater) of the test specimens and additionally, in a second experimental setup, the effects of five potential polymer degradation products were detected by 72 h algae growth inhibition tests with Desmodesmus subspicatus. Results clearly indicate inhibitory effects on algae growth by contaminants in the storage water of stressed plastics with increasing growth inhibition of proceeding hydrolysis and UV stress times. Different polymers caused variable inhibitions of algae growth with stronger inhibitions by PS and less effects by PLA and the mixed layer of both. Moreover, not microplastic particles but the resulting dissolved degradation products after aging caused the ecotoxicological effects—with strong effects by the oxidized degradation products. The existing data highlight the relevance of plastic aging as a framework for microplastic ecotoxicity evaluation and allow a proof of concept.