Individual and mixture toxicity of pharmaceuticals towards microalgae. Role of intracellular free Ca2+

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología. Fecha de lectura: 30-06-2017Esta tesis tiene embargado el acceso al texto completo hasta el 30-12-2018The thesis was supported by the Spanish Government (Projects MICIN CGL2010-15675 and MINECO CTM2013-45775-C2-2-R) and the Dirección General de Universidades e Investigación de la Comunidad de Madrid, Research Network (Comunidad de Madrid S-2009/AMB/1511

Luminescent microbial bioassays and microalgal biosensors as tools for environmental toxicity evaluation

This chapter deals with toxicity bioassays and biosensors based on luminescent microorganisms that report on global toxicity of a sample in such a way that luminescence is reduced or inhibited in the presence of toxic compounds that impair metabolism. Both natural as well as recombinant microorganisms are considered. A detailed description of their main characteristics and environmental applications is reported. A few examples of bioassays for detecting oxidative stress (both bioluminescent and fluorescent bioreporters) are also mentioned and discussed as reactive oxygen species (ROS) formation and subsequent oxidative stress if the antioxidant defenses of the cells are surpassed is one of the main mechanisms of toxicity for most pollutants. There is also a section dedicated to microalgal–based biosensors given their ecological relevance as primary producers, their easiness of culture and immobilization in different matrices, ability to acclimate to low nutrients conditions and ubiquity in aquatic environments. The most used toxicity endpoints for this type of biosensors are the alteration of photosynthetic activity (optical and amperometric biosensors) and the inhibition of enzymes such as alkaline phosphatase (APA) or sterases (mostly conductometric biosensors). The main information is shown in tables that include the microorganisms, their main characteristics (reporter gene systems, transducer types for biosensors) and their main environmental applications as well as relevant references. Although some of these bioassays have already been standardized by different international organizations, there are still many which are also promising tools for environmental global toxicity evaluation and should be fully validated and standardized for regulatory purposesThis research was supported by the Spanish Ministry of Economy and Competitiveness (MINECO), grant CTM2016-74927-C2-2-

Early and differential bacterial colonization on microplastics deployed into the effluents of wastewater treatment plants

Título del Post Print: Early and differential bacterial colonization on microplasticsMicrobial colonization of microplastics (MPs) in aquatic ecosystems is a well-known phenomenon; however, there is insufficient knowledge of the early colonization phase. Wastewater treatment plant (WWTP) effluents have been proposed as important pathways for MPs entry and transport in aquatic environments and are hotspots of bacterial pathogens and antibiotic resistance genes (ARGs). This study aimed at characterizing bacterial communities in the early stage of biofilm formation on seven different types of MPs deployed in two different WWTPs effluents as well as measuring the relative abundance of two ARGs (sulI and tetM) on the tested MPs. Illumina Miseq sequencing of the 16S rRNA showed significant higher diversity of bacteria on MPs in comparison with free-living bacteria in the WWTP effluents. β-diversity analysis showed that the in situ environment (sampling site) and hydrophobicity, to a lesser extent, had a role in the early bacterial colonization phase. An early colonization phase MPs-core microbiome could be identified. Furthermore, specific core microbiomes for each type of polymer suggested that each type might select early attachment of bacteria. Although the tested WWTP effluent waters contained antibiotic resistant bacteria (ARBs) harboring the sulI and tetM ARGs, MPs concentrated ARBs harboring the sulI gene but not tetM. These results highlight the relevance of the early attachment phase in the development of bacterial biofilms on different types of MP polymers and the role that different types of polymers might have facilitating the attachment of specific bacteria, some of which might carry ARGsFinancial support was provided by the Spanish Ministry of Economy and Competitiveness (CTM2016-74927-C2-1/2-R

Microplastics in snow of a high mountain national park: El Teide, Tenerife (Canary Islands, Spain)

Human activities have introduced high amounts of microplastics (MPs) into the atmosphere that can be transported long distances and be later deposited in terrestrial and aquatic ecosystems with precipitation (rain or snow). In this work, it has been assessed the presence of MPs in the snow of El Teide National Park (Tenerife, Canary Islands, Spain, 2150–3200 m above sea level) after two storm episodes (January–February 2021). The data set (63 samples) was divided into three groups: i) samples from “accessible areas” (after the first storm episode and in places with a strong previous/recent anthropogenic activity); ii) “pristine areas” (after the second storm episode, in places with no previous anthropogenic activity), and iii) “climbing areas” (after the second storm episode, in places with a soft recent anthropogenic activity). Similar pattern profiles were observed among sampling sites in terms of morphology, colour and size (predominance of blue and black microfibers of 250–750 μm length), as well as in composition (predominance of cellulosic -either natural or semisynthetic-, with a 62.7 %, polyester, 20.9 %, and acrylic, 6.3 %, microfibers); however, significant differences in MPs concentrations were found between samples collected in pristine areas (average concentration of 51 ± 72 items/L) and those obtained in places with a previous anthropogenic activity (average concentration of 167 ± 104 and 188 ± 164 items/L in “accessible areas” and “climbing areas”, respectively). This study shows, for the first time, the presence of MPs in snow samples from a high altitude protected area on an insular territory and suggests that the sources of these contaminants could be atmospheric transport and local human outdoor activitie

Recycled wastewater as a potential source of microplastics in irrigated soils from an arid-insular territory (Fuerteventura, Spain)

In this work, the occurrence of microplastics (MPs) in irrigation recycled wastewaters (RWWs) and a desalinated brackish water (DBW) from the arid territory of Fuerteventura (Canary Islands, Spain) was studied. Besides, the presence of MPs in two types of soils (sandy-loam and clay-loamy; with no mulch film or fertilization with sewage sludge applied) irrigated with both water qualities was addressed. Results showed the prevalence presence of cellulosic and polyester microfibers (between 84.4 and 100%) of blue and transparent colors (up to 55.6 and 33.3%, respectively), with an average length of 786.9 ± 812.1 μm in the water samples. DBW had the lowest MP concentration (2.0 ± 2.0 items·L−1) while RWW showed concentrations up to 40.0 ± 19.0 items·L−1. Similarities were also observed between the MPs types and sizes found in both soils top layer (0–5 cm), with an average concentration three times greater in soil irrigated with RWW than in soil under DBW irrigation (159 ± 338 vs. 46 ± 92 items·kg−1, respectively). In addition, no MPs were extracted from non-irrigated/non-cultivated soils, suggesting agricultural activities as the unique source of MPs in soils of this arid area. Results show that RWWs constitute a potential source of MPs in irrigated soils that should be considered among other pros and cons linked to the use of this water quality in agricultural arid land

Microplastics as vectors of the antibiotics azithromycin and clarithromycin: effects towards freshwater microalgae

Water pollution due to microplastics (MPs) is recognized as a major anthropogenic impact. Once MPs reach the ecosystems, they are exposed to a variety of other pollutants, which can be sorbed on them, transported and eventually desorbed. In this work, we tested the hypothesis that MPs can behave as conveyors for delivering chemicals toxic to aquatic microorganisms by investigating the vector role of MPs of polyethylene terephthalate (PET), polylactic acid (PLA), polyoxymethylene (POM) and polystyrene (PS) to the macrolide antibiotics azithromycin (AZI) and clarithromycin (CLA). AZI and CLA were chosen, as they are included in the Watch List for EU monitoring concerning water policy by Decision (EU) 2018/840. MPs were loaded in contact with 500 μg/L of AZI or 1000 μg/L of CLA. Results showed that both antibiotics were sorbed on all tested MPs. The more hydrophobic AZI was sorbed in higher proportion than CLA. Both antibiotics were desorbed from MPs upon contact with water with percentages between 14.6 ± 2.6% for AZI and 1.9 ± 1.4% for CLA of the concentrations to which the MPs were initially exposed. Virgin MPs were not toxic to the cyanobacterium Anabaena sp. PCC7120. However, antibiotic-loaded MPs significantly inhibited the growth and chlorophyll content of the cyanobacterium. Most of the sorbed antibiotics became released upon contact with cyanobacterial cultures, which was the cause for the observed toxicity. Therefore, MPs can play a role as vectors of antibiotics in freshwaters systems affecting the basic trophic level of photosynthetic microorganismsFinancial support was provided by the Spanish Ministry of Economy and Competitiveness (CTM2016-74927C2-1-R/2-R). We also thank the EnviroPlaNet Network Thematic Network of Micro and Nanoplastics in the Environment (RED2018-102345-T; Ministerio de Ciencia, Innovacion y Universidades

Toxicity of superparamagnetic iron oxide nanoparticles to the microalga Chlamydomonas reinhardtii

Superparamagnetic iron oxide nanoparticles (SPION) have been widely studied for different biomedical and environmental applications. In this study we evaluated the toxicity and potential alterations of relevant physiological parameters caused to the microalga Chlamydomonas reinhardtii (C. reinhardtii) upon exposure to SPION. The results showed dose-dependent toxicity. A mechanistic study combining flow cytometry and physiological endpoints showed a toxic response consisting of a decrease in metabolic activity, increased oxidative stress and alterations in the mitochondrial membrane potential. Additionally, and due to the light absorption of SPION suspensions, we observed a significant shading effect, causing a marked decrease in photosynthetic activity. In this work, we demonstrated for the first time, the internalization of SPION by endocytosis in C. reinhardtii. These results demonstrated that SPION pose a potential risk for the environment if not managed properlyThis research is supported by CTM2013-45775-C2-1/2-R, CTM2016-74927-C2-1,2-R and MAT2015-71806-R grants from MINEC

Secondary nanoplastics released from a biodegradable microplastic severely impact freshwater environments

This article is part of the themed collection: Environmental Science: Nano Recent HOT Articles https://pubs.rsc.org/en/journals/articlecollectionlanding?sercode=en&themeid=280a8 9ca-3eed-4abe-ae65-c856206f6c3c Article selected by the Editors in Chief of Environmental Science journals: DOI: 10.1039/D0EM90014A (Editorial)Over the last five decades, plastics production has increased as a consequence of their use in strategic sectors causing damage on aquatic ecosystems. In this context, biodegradable plastics have emerged as an ecological alternative because they are easily degradable in the environment. Despite the recent advances in the field of plastic ecotoxicology, the ecological impact of secondary nanoplastics (nanoplastics resulting from natural degradation of micro and macro plastics) in the environment remains poorly understood. Here, we have investigated the effects of secondary nanoplastics of polyhydroxybutyrate (PHB), a biodegradable plastic, on three representative organisms of aquatic ecosystems. Secondary PHB-nanoplastics were produced from PHB-microplastics by abiotic degradation under environmentally representative conditions. Secondary PHB-nanoplastics induced a significant decrease in cellular growth and altered relevant physiological parameters in all organisms. We investigated whether the observed toxicity was exerted by PHB-nanoplastics themselves or by other abiotic degradation products released from PHB-microplastics. An experiment was run in which PHB-nanoplastics were removed by ultrafiltration; the resulting supernatant was not toxic to the organisms, ruling out the presence of toxic chemicals in the PHB-microplastics. In addition, we have performed a complete physicochemical characterization confirming the presence of secondary PHB-nanoplastics in the 75-200 nm range. All results put together indicated that secondary PHB-nanoplastics released as a consequence of abiotic degradation of PHB-microplastics were harmful for the tested organisms, suggesting that biodegradable plastic does not mean safe for the environment in the case of PH

Microplastics determination in gastrointestinal tracts of european sea bass (Dicentrarchus labrax) and gilt-head sea bream (Sparus aurata) from Tenerife (Canary Islands, Spain)

Microplastic pollution has an extremely widespread distribution, to the extent that microplastics could be ingested by aquatic organisms, including species of commercial importance for fisheries and aquaculture. In this work, the anthropogenic particles content of the gastrointestinal tracts of 86 individuals of cultivated European sea bass (Dicentrarchus labrax, n = 45) and gilt-head sea bream (Sparus aurata, n = 41) from Tenerife (Canary Islands, Spain) was determined. Samples were bought at local markets and directly transported to the laboratory. After the dissection of the fishes and digestion of the gastrointestinal tracts in 10% KOH (w/v) at 60◦C for 24 h, the digests were filtered (50 µm stainless-steel mesh) and visualized under a stereomicroscope, finding that most of the items were colourless (47.7% for Dicentrarchus labrax and 60.9% for Sparus aurata) and blue (35.3% vs. 24.8%) microfibers, with an average length of 1957 ± 1699 µm and 1988 ± 1853 µm, respectively. Moreover, 15.3% of the microfibres were analysed by Fourier transform infrared spec-troscopy, showing the prevalence of cellulosic fibres together with polyester, polyacrylonitrile, and poly(ether-urethane). This pattern (microplastics shapes, colours, sizes, and composition) clearly agrees with previous studies carried out in the Canary Islands region regarding the determination of microplastics in the marine environmen

Microplastics in sediments of artificially recharged lagoons: case study in a Biosphere Reserve

We studied the occurrence of microplastics in sediments of artificially and non-artificially recharged lagoons from the network of endorheic wetlands called “La Mancha Húmeda”, declared Biosphere Reserve by UNESCO. The particles sampled in this study covered the 25 μm–5 mm range. Films were the dominant microplastic typology in non-artificially recharged lagoons, while fibres and fragments were more abundant in those receiving wastewater. The concentration of microplastics in sediments reached up to 24.4 ± 5.2 microplastics/g, while plastic litter counts yielded <1 particle/g in non-wastewater receiving lagoons. Eleven types of plastic were identified using Micro-Fourier Transform Infrared Spectroscopy (micro-FTIR), the most abundant being the polyolefins polyethylene and polypropylene, and polyester and acrylic fibres. The statistical analysis of FTIR spectra confirmed the similarity between samples taken from recharged lagoons and wastewater treatment plant effluents. Overall, our results showed that endorheic lagoons are very sensitive to the accumulation of persistent pollutants, which include microplastics. The recharge of lagoons with wastewater effluents to maintain water levels, even if correctly treated according to current standards, is not a sustainable practice. Due to the closed character of endorheic basins, the continuous input of wastewater led to the accumulation of microplastics in sediments of wastewater receiving lagoons up to 40 times over non-recharged lagoon