1
|
Millet RT, Santos JP, Slaveykova VI. Exploring the subcellular distribution of mercury in green alga Chlamydomonas reinhardtii and diatom Cyclotella meneghiniana: A comparative study. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2024; 267:106836. [PMID: 38232614 DOI: 10.1016/j.aquatox.2024.106836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/09/2024] [Accepted: 01/11/2024] [Indexed: 01/19/2024]
Abstract
Mercury (Hg) is a priority pollutant of global concern because of its toxicity, its ability to bioaccumulate throughout the food web and reach significant concentrations in top predators. Phytoplankton bioconcentrate large amounts of Hg and play a key role in the entry of Hg into the aquatic food web. However, the subcellular distribution of Hg in freshwater phytoplankton, known to affect it toxicity and trophic transfer is understudied. The present study aimed at investigating the accumulation of inorganic Hg (iHg) and its subcellular distribution in freshwater phytoplankton species. To this end green alga Chlamydomonas reinhardtii and diatom Cyclotella meneghiniana were exposed to 10 and 100 nM of iHg for 2 h. The concentrations of Hg in the adsorbed, intracellular and subcellular (granules, debris, organelles, heat-stable peptides (HSP) and heat-denaturable proteins (HDP)) fractions were determined. The results showed that C. meneghiniana accumulated more Hg compared to C. reinhardtii at both iHg exposure concentrations (10 nM: 4.41 ± 0.74 vs. 1.10 ± 0.25 amol cell-1; 100 nM: 79.35 ± 10.78 vs. 38.31 ± 4.15 amol cell-1). The evaluation of the subcellular distribution of Hg, revealed that the majority of Hg was concentrated in the organelles fraction (59.7 % and 74.6 %) in the green algae. In the diatom, Hg was mainly found in the organelles (40.9 % and 33.3%) and in the HSP fractions (26.8 % and 40.1 %). The proportion of Hg in HDP fraction decreased in favor of the organelles fraction in C. reinhardtii when the exposure concentration increased, whereas the proportions in the debris and organelles fractions decreased in favor of HSP fraction in C. meneghiniana. This study provides pioneering information on the subcellular distribution of Hg within in freshwater phytoplankton, a knowledge that is essential to understand the toxicity and trophic transfer of Hg in contaminated aquatic environment.
Collapse
Affiliation(s)
- Rémy T Millet
- University of Geneva, Faculty of Sciences, Earth and Environment Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, 66 Blvd Carl-Vogt, CH 1211 Geneva, Switzerland
| | - João P Santos
- University of Geneva, Faculty of Sciences, Earth and Environment Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, 66 Blvd Carl-Vogt, CH 1211 Geneva, Switzerland
| | - Vera I Slaveykova
- University of Geneva, Faculty of Sciences, Earth and Environment Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, 66 Blvd Carl-Vogt, CH 1211 Geneva, Switzerland.
| |
Collapse
|
2
|
Cheng Q, Liu Y, Xu L, Ye J, Wang Q, Lin H, Ma J. Regulation and role of extracellular polymeric substances in the defensive responses of Dictyosphaerium sp. to enrofloxacin stress. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 896:165302. [PMID: 37414177 DOI: 10.1016/j.scitotenv.2023.165302] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 06/23/2023] [Accepted: 07/01/2023] [Indexed: 07/08/2023]
Abstract
Algae are susceptible to enrofloxacin (ENR), an antibiotic frequently detected in aquatic environments. However, algal responses, especially the secretion and roles of extracellular polymeric substances (EPS), under ENR exposure remain unknown. This study is the first to elucidate the variation in algal EPS triggered by ENR at both the physiological and molecular levels. The results showed that EPS were significantly (P < 0.05) overproduced along with increased polysaccharide and protein contents in algae exposed to 0.05, 0.5, and 5 mg/L ENR. Secretion of aromatic proteins, especially tryptophan-like substances with more functional groups or aromatic rings, was specifically stimulated. Furthermore, the genes with upregulated expression related to carbon fixation, aromatic protein biosynthesis, and carbohydrate metabolism are direct causes of enhanced EPS secretion. Improved EPS levels increased the cell surface hydrophobicity and provided more adsorption sites for ENR, which strengthened the van der Waals interaction and reduced ENR internalization. The hormesis effects of ENR were alleviated, as illustrated by the less affected cell density, chlorophyll a/b, and carotenoids biosynthesis in algae with EPS. These findings demonstrate the involvement of EPS in algal ENR resistance and promote a deeper understanding of the ecological effects of ENR in aquatic environments.
Collapse
Affiliation(s)
- Qilu Cheng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, The Institute of Environment, Resource, Soil and Fertilizers, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Yangzhi Liu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, The Institute of Environment, Resource, Soil and Fertilizers, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Ligen Xu
- College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Jing Ye
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, The Institute of Environment, Resource, Soil and Fertilizers, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Qiang Wang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, The Institute of Environment, Resource, Soil and Fertilizers, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Hui Lin
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, The Institute of Environment, Resource, Soil and Fertilizers, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Junwei Ma
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, The Institute of Environment, Resource, Soil and Fertilizers, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
| |
Collapse
|
3
|
Leclerc M, Wauthy M, Planas D, Amyot M. How do metals interact with periphytic biofilms? THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 876:162838. [PMID: 36924968 DOI: 10.1016/j.scitotenv.2023.162838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 03/08/2023] [Accepted: 03/09/2023] [Indexed: 06/18/2023]
Abstract
Extracellular matrix of periphyton has complex structural and chemical composition regulating metal transfer within biofilms with consequences for metal transfer to aquatic food webs. We investigated which metal species were retained in the loosely (LB) and the tightly bound (TB) fractions of the periphyton matrix from three pristine lakes at different growth stages. We measured the fluorescent dissolved organic matter (FDOM) composition with parallel factor analysis (PARAFAC) and the co-occurrence of essential and non-essential metals with FDOM in the two matrix fractions. The LB and TB fractions of periphyton had distinct fluorescence composition from the water column. The PARAFAC model identified five components, including two (C2 and C4) appearing to be of periphytic origin. The humic-like C2 was almost exclusive to periphyton and the tryptophan-like C4, associated to biofilm phototrophy, represented up to 47.0 ± 7.3 % of total fluorescence in the LB fraction. Most metals had significant positive relationships with four FDOM components in the LB fraction while C2 was the only component in the TB fraction to show such significant relationships. Components in the LB fraction seemed to act as scavengers for metals, preventing them from reaching the cellular fraction, while C2 from the TB fraction was likely promoting the bioavailability of essential metals for microorganisms inside periphyton. This study highlights the contrasting roles of the extracellular matrix on metal mobility beyond the usually proposed protection mechanisms. We suggest an experimental model for the study of metal regulation processes of the periphytic extracellular polymeric substances with a focus on the components produced by microorganisms within periphyton and their distribution in the different matrix fractions.
Collapse
Affiliation(s)
- Maxime Leclerc
- GRIL, Département de Sciences Biologiques, Université de Montréal, 1375 Thérèse-Lavoie-Roux Ave., Montréal, QC H2V 0B3, Canada; GRIL, GEOTOP, Département de Sciences Biologiques, Université du Québec à Montréal, 141 Président-Kennedy Ave., Montréal, QC H2X 1Y4, Canada
| | - Maxime Wauthy
- GRIL, Département de Sciences Biologiques, Université de Montréal, 1375 Thérèse-Lavoie-Roux Ave., Montréal, QC H2V 0B3, Canada
| | - Dolors Planas
- GRIL, GEOTOP, Département de Sciences Biologiques, Université du Québec à Montréal, 141 Président-Kennedy Ave., Montréal, QC H2X 1Y4, Canada
| | - Marc Amyot
- GRIL, Département de Sciences Biologiques, Université de Montréal, 1375 Thérèse-Lavoie-Roux Ave., Montréal, QC H2V 0B3, Canada.
| |
Collapse
|
4
|
Li C, Li P, Fu H, Chen J, Ye M, Zhai S, Hu F, Zhang C, Ge Y, Fortin C. A comparative study of the accumulation and detoxification of copper and zinc in Chlamydomonas reinhardtii: The role of extracellular polymeric substances. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 871:161995. [PMID: 36739008 DOI: 10.1016/j.scitotenv.2023.161995] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 01/28/2023] [Accepted: 01/30/2023] [Indexed: 06/18/2023]
Abstract
Extracellular polymeric substances (EPS) form an interface between microalgae and the surrounding water environment. Copper (Cu) and zinc (Zn) are essential micronutrients but may negatively affect microbial growth when their concentrations reach toxic thresholds. However, how EPS affect the accumulation and resistance of Cu and Zn in microalgae remains largely unknown. Here, we investigated EPS production upon Cu/Zn exposure and compared the tolerance strategies to the two metals by Chlamydomonas reinhardtii with and without EPS. Microalgal EPS synthesis was induced by Cu/Zn treatments, and the functional groups of polysaccharides and proteins were involved in complexation with metal ions. The extraction of EPS aggravated the toxicity and reduced the removal of metals from solution, but the effect was more pronounced for Cu than for Zn. Copper bound on the cell surface accounted for 54.6 ± 2.0 % of the Cu accumulated by C. reinhardtii, whose EPS components strongly correlated with Cu adsorption. In contrast, 74.3 ± 3.0 % of accumulated Zn was absorbed in cells, and glutathione synthesis was significantly induced. Redundancy and linear correlation analyses showed that the polysaccharide, protein and DNA contents in EPS were significantly correlated with Cu accumulation, absorption and adsorption but not with Zn. Data fitted to a Michaelis-Menten model further showed that the EPS-intact cells had higher binding capacity for Cu2+ but not for Zn2+. These differential impacts of EPS on Cu/Zn sorption and detoxification contribute to a more comprehensive understanding of the roles of microalgal EPS in the biogeochemical cycle of metals.
Collapse
Affiliation(s)
- Chonghua Li
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Peihuan Li
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Hongxuan Fu
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiale Chen
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Menglei Ye
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Suhua Zhai
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Fan Hu
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Chunhua Zhang
- Demonstration Laboratory of Element and Life Science Research, Laboratory Centre of Life Science, College of Life Science, Nanjing Agricultural University, Nanjing 210095, China
| | - Ying Ge
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
| | - Claude Fortin
- EcotoQ, Institut National de la Recherche Scientifique, Centre Eau Terre Environnement, 490 de la Couronne, Québec, QC G1K 9A9, Canada
| |
Collapse
|
5
|
Yang L, Yang Q, Lin L, Luan T, Tam NFY. Characterization of benthic biofilms in mangrove sediments and their variation in response to nutrients and contaminants. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 857:159391. [PMID: 36240915 DOI: 10.1016/j.scitotenv.2022.159391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/30/2022] [Accepted: 10/08/2022] [Indexed: 06/16/2023]
Abstract
Diatom-dominated biofilms and associated extracellular polymeric substances (EPS) may adapt to the stress of long-term exposure to nutrients and anthropogenic contaminants. However, such interactions in contaminated mangrove sediments have rarely been reported. Based on the in situ characterization of biofilm components and environmental factors, the present study aimed to explore the key factors involved in shaping sediment biofilms through correlational and multivariate analyses. The pennate diatom Navicula is the core taxon that plays a crucial role in balancing the abundance of Nitzschia and Cyclotella, and is the main producer of bound-polysaccharides. The taxa composition shifts in a high N/P matrix, with the populations of pennate diatoms increasing but that of centric diatoms decreasing. High nutrient concentrations yield more number of diatoms and elevated levels of EPS. Bacteria are the main consumers of EPS and tend to be more symbiotic with Nitzschia than the other two diatom taxa. Some bound-polysaccharides dominated by arabinose and glucose units are transformed into the colloidal fraction, whereas other conservative ones serve as structural materials in concert with the bound-proteins. The planktonic phase of Cyclotella breaks down the structural EPS secreted by pennate diatoms in a process that directly affects the dynamic renewal of benthic biofilms. Most heavy metals as well as bisphenol A inhibit the abundance of bacteria and diatoms but enhance most EPS fractions except bound-polysaccharides. The response of structural EPS to specific contaminants varies, exhibiting increases in Co and Ni levels but decreases in nonylphenol and methylparaben levels. The present study improves our understanding of the microbial carbon loop of benthic biofilms in mangrove ecosystems under stress by nutrients and mixed contaminants.
Collapse
Affiliation(s)
- Lihua Yang
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Qian Yang
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University, Guangzhou 510275, China; State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510600, China
| | - Li Lin
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Tiangang Luan
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Nora F Y Tam
- School of Science and Technology, Hong Kong Metropolitan University, Hong Kong, China; State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, Hong Kong, China.
| |
Collapse
|
6
|
Gebara RC, Alho LDOG, Mansano ADS, Rocha GS, Melão MDGG. Single and combined effects of Zn and Al on photosystem II of the green microalgae Raphidocelis subcapitata assessed by pulse-amplitude modulated (PAM) fluorometry. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2023; 254:106369. [PMID: 36502662 DOI: 10.1016/j.aquatox.2022.106369] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 12/02/2022] [Accepted: 12/03/2022] [Indexed: 06/17/2023]
Abstract
Increasing metal concentrations in aquatic environments are mainly due to anthropogenic actions, which is a matter of concern for the biodiversity of aquatic biota. It is known that metals coexist in environments, however environmental risk assessments do not usually take into account the effects of these mixtures. We aimed to test Zn and Al mixtures on the photosynthetic apparatus of a green microalga, for the first time, using PAM fluorometry. After 72 h exposure, single concentrations from 0.08 to 0.46 µM Zn and 22.24 to 37.06 µM Al affected the photosynthetic parameters of Raphidocelis subcapitata. Metals affected the efficiency of the oxygen-evolving complex - OEC (F0/Fv), increasing it by 25% at 0.46 µM Zn and by 82% at 37.06 µM Al - concentrations where, 57% and 78% of growth inhibition occurred, respectively. We observed that the algal growth was more sensitive to infer Zn toxicity, while F0/Fv was more affected by Al. Regarding quenching, there was an increase in passive energy dissipation ((Y(NO)) at 0.46 µM Zn, and we observed an increase in both regulated ((NPQ and Y(NPQ)) and non-regulated energy dissipation ((qN and (Y(NO)) at 37.06 µM Al. Our results showed synergism and antagonism at different concentrations in mixtures, the antagonism prevailing at higher metal concentrations and, in some cases, synergism at lower concentrations of Zn and Al. Since we observe more than additive and less than additive effects, it is of the utmost importance to take mixture toxicity tests into account when performing risk assessments on green algae.
Collapse
Affiliation(s)
- Renan Castelhano Gebara
- Department of Hydrobiology. Universidade Federal de São Carlos (UFSCar). Rodovia Washington Luís, Km 235, 13565-905, São Carlos, SP, Brazil; Post-Graduate Program in Ecology and Natural Resources (PPGERN), Universidade Federal de São Carlos (UFSCar). Rodovia Washington Luís, Km 235, 13565-905, São Carlos, SP, Brazil.
| | - Lays de Oliveira Gonçalves Alho
- Department of Hydrobiology. Universidade Federal de São Carlos (UFSCar). Rodovia Washington Luís, Km 235, 13565-905, São Carlos, SP, Brazil; Post-Graduate Program in Ecology and Natural Resources (PPGERN), Universidade Federal de São Carlos (UFSCar). Rodovia Washington Luís, Km 235, 13565-905, São Carlos, SP, Brazil
| | - Adrislaine da Silva Mansano
- Department of Hydrobiology. Universidade Federal de São Carlos (UFSCar). Rodovia Washington Luís, Km 235, 13565-905, São Carlos, SP, Brazil; Post-Graduate Program in Ecology and Natural Resources (PPGERN), Universidade Federal de São Carlos (UFSCar). Rodovia Washington Luís, Km 235, 13565-905, São Carlos, SP, Brazil
| | - Giseli Swerts Rocha
- NEEA/CRHEA/SHS, São Carlos School of Engineering, Universidade de São Paulo (USP), Av. Trabalhador São-carlense, 400, 13560-970 São Carlos, Brazil
| | - Maria da Graça Gama Melão
- Department of Hydrobiology. Universidade Federal de São Carlos (UFSCar). Rodovia Washington Luís, Km 235, 13565-905, São Carlos, SP, Brazil; Post-Graduate Program in Ecology and Natural Resources (PPGERN), Universidade Federal de São Carlos (UFSCar). Rodovia Washington Luís, Km 235, 13565-905, São Carlos, SP, Brazil
| |
Collapse
|
7
|
Laderriere V, Morin S, Eon M, Fortin C. Vulnerability and tolerance to nickel of periphytic biofilm harvested in summer and winter. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 315:120223. [PMID: 36191798 DOI: 10.1016/j.envpol.2022.120223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 09/14/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
Metals are naturally present in freshwater ecosystems but anthropogenic activities like mining operations represent a long-standing concern. Metals released into aquatic environments may affect microbial communities such as periphytic biofilm, which plays a key role as a primary producer in stream ecosystems. Using two 28-day microcosm studies involving two different photoperiods (light/dark cycle of 16/8 vs 8/16), the present study assessed the effects of four increasing nickel (Ni) concentrations (0-6 μM) on two natural biofilm communities collected at different seasons (summer and winter). The two communities were characterized by different structural profiles and showed significant differences in Ni accumulated content for each treatment. For instance, the biofilm metal content was four times higher in the case of summer biofilm at the highest Ni treatment and after 28 days of exposure. Biomarkers examined targeted both heterotrophic and autotrophic organisms. For heterotrophs, the β-glucosidase and β-glucosaminidase showed no marked effects of Ni exposure and were globally similar between the two communities suggesting low toxicity. However, the photosynthetic yield confirmed the toxicity of Ni on autotrophs with maximum inhibition of 81 ± 7% and 60 ± 1% respectively for the summer and winter biofilms. Furthermore, biofilms previously exposed to the highest long-term Ni concentration ([Ni2+] = 6 μM) revealed no acute effects in subsequent toxicity based on the PSII yield, suggesting a tolerance acquisition by the phototrophic community. Taken together, the results suggest that the biofilm response to Ni exposure was dependent of the function considered and that descriptors such as biofilm metal content could be seasonally dependent, information of great importance in a context of biomonitoring.
Collapse
Affiliation(s)
- Vincent Laderriere
- INRS - ETE, 490 Rue de la Couronne, Québec, Canada; EcotoQ, 490 Rue de la Couronne, Québec, Canada.
| | - Soizic Morin
- EcotoQ, 490 Rue de la Couronne, Québec, Canada; INRAE, 50 Avenue de Verdun, Cestas, France.
| | | | - Claude Fortin
- INRS - ETE, 490 Rue de la Couronne, Québec, Canada; EcotoQ, 490 Rue de la Couronne, Québec, Canada.
| |
Collapse
|
8
|
Courcoul C, Leflaive J, Ferriol J, Boulêtreau S. The sensitivity of aquatic microbial communities to a complex agricultural contaminant depends on previous drought conditions. WATER RESEARCH 2022; 217:118396. [PMID: 35413563 DOI: 10.1016/j.watres.2022.118396] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 03/29/2022] [Accepted: 04/01/2022] [Indexed: 06/14/2023]
Abstract
In intermittent rivers, which represent a prominent part of worldwide rivers, aquatic organisms are exposed to sequential disturbances including flow cessation, potentially associated with water warming, desiccation process and flow resumption. At flow resumption, pollutants stored in soil and washed by rainfalls can reach fresh waters. The interaction between contamination and river intermittency is poorly understood. In this study, we aimed at understanding in what extent the intensity of dry period combined or not to water warming drives the sensitivity of aquatic communities to a complex agricultural run-off (ARO) during rewetting. Phototrophic biofilms, at the basis of freshwater food webs, were chosen as a model of community. Biofilms grown in laboratory were first exposed to a disturbance crossing two temperature conditions (not warmed, 22°C or warmed, 32°C) and three dry periods (no drying, short (3 days), or long (3 months)). Then they were exposed to a chemical mix of nitrates, copper and 3 pesticides at 6 gradual concentrations. Various descriptors associated with biofilm structure and function were assessed one week after ARO addition. When undisturbed biofilms were exposed to ARO, they shifted toward a more heterotrophic state as they lost algal richness and diversity, and gross primary production tended to decrease. Warming alone only slightly modified the sensitivity of biofilms to ARO, with lower effects on algal richness and a trend to increase the effect on gross primary production. In contrast, the association of warming and a dry period strongly modified the sensitivity to ARO, certainly due to the selection of generalist species and/or physiological acclimation inducted by the first disturbance. This study emphasizes the importance of considering water intermittency in the management of the ecological risk of chemicals in aquatic ecosystems.
Collapse
Affiliation(s)
- Camille Courcoul
- Laboratoire d'Ecologie Fonctionnelle et Environnement de Toulouse, Université de Toulouse, CNRS UMR 5245, INPT, UPS, Toulouse, France.
| | - Joséphine Leflaive
- Laboratoire d'Ecologie Fonctionnelle et Environnement de Toulouse, Université de Toulouse, CNRS UMR 5245, INPT, UPS, Toulouse, France
| | - Jessica Ferriol
- Laboratoire d'Ecologie Fonctionnelle et Environnement de Toulouse, Université de Toulouse, CNRS UMR 5245, INPT, UPS, Toulouse, France
| | - Stéphanie Boulêtreau
- Laboratoire d'Ecologie Fonctionnelle et Environnement de Toulouse, Université de Toulouse, CNRS UMR 5245, INPT, UPS, Toulouse, France
| |
Collapse
|
9
|
Loustau E, Leflaive J, Boscus C, Amalric Q, Ferriol J, Oleinikova O, Pokrovsky OS, Girbal-Neuhauser E, Rols JL. The Response of Extracellular Polymeric Substances Production by Phototrophic Biofilms to a Sequential Disturbance Strongly Depends on Environmental Conditions. Front Microbiol 2021; 12:742027. [PMID: 34707592 PMCID: PMC8542934 DOI: 10.3389/fmicb.2021.742027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 09/20/2021] [Indexed: 12/03/2022] Open
Abstract
Phototrophic biofilms are exposed to multiple stressors that can affect them both directly and indirectly. By modifying either the composition of the community or the physiology of the microorganisms, press stressors may indirectly impact the ability of the biofilms to cope with disturbances. Extracellular polymeric substances (EPS) produced by the biofilm are known to play an important role in its resilience to various stresses. The aim of this study was to decipher to what extent slight modifications of environmental conditions could alter the resilience of phototrophic biofilm EPS to a realistic sequential disturbance (4-day copper exposure followed by a 14-day dry period). By using very simplified biofilms with a single algal strain, we focused solely on physiological effects. The biofilms, composed by the non-axenic strains of a green alga (Uronema confervicolum) or a diatom (Nitzschia palea) were grown in artificial channels in six different conditions of light intensity, temperature and phosphorous concentration. EPS quantity (total organic carbon) and quality (ratio protein/polysaccharide, PN/PS) were measured before and at the end of the disturbance, and after a 14-day rewetting period. The diatom biofilm accumulated more biomass at the highest temperature, with lower EPS content and lower PN/PS ratio while green alga biofilm accumulated more biomass at the highest light condition with lower EPS content and lower PN/PS ratio. Temperature, light intensity, and P concentration significantly modified the resistance and/or recovery of EPS quality and quantity, differently for the two biofilms. An increase in light intensity, which had effect neither on the diatom biofilm growth nor on EPS production before disturbance, increased the resistance of EPS quantity and the resilience of EPS quality. These results emphasize the importance of considering the modulation of community resilience ability by environmental conditions, which remains scarce in the literature.
Collapse
Affiliation(s)
- Emilie Loustau
- Laboratoire Ecologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France.,LBAE, Université de Toulouse, Université Toulouse 3 - Paul Sabatier (UPS), Auch, France
| | - Joséphine Leflaive
- Laboratoire Ecologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France
| | - Claire Boscus
- Laboratoire Ecologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France
| | - Quentin Amalric
- Laboratoire Ecologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France
| | - Jessica Ferriol
- Laboratoire Ecologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France
| | - Olga Oleinikova
- GET, Université de Toulouse, CNRS, IRD, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France
| | - Oleg S Pokrovsky
- GET, Université de Toulouse, CNRS, IRD, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France.,BIO-GEO-CLIM Laboratory, Tomsk State University, Tomsk, Russia
| | | | - Jean-Luc Rols
- Laboratoire Ecologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France
| |
Collapse
|
10
|
Yang Q, Xu W, Luan T, Pan T, Yang L, Lin L. Comparative responses of cell growth and related extracellular polymeric substances in Tetraselmis sp. to nonylphenol, bisphenol A and 17α-ethinylestradiol. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 274:116605. [PMID: 33545521 DOI: 10.1016/j.envpol.2021.116605] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/19/2021] [Accepted: 01/24/2021] [Indexed: 06/12/2023]
Abstract
Estuarine ecosystems near mega-cities are sinks of anthropogenic endocrine disrupting chemicals (EDCs). As the most important primary producer, indigenous microalgae and their secreted extracellular polymeric substances (EPSs) might interact with EDCs and contribute to their fate and risk. Tetraselmis sp. is a representative model of estuarine microalga, for which EDC toxicity and its effects on EPS synthesis have rarely been studied. Through microalgal isolation, algal cell growth tests, EDC removal and the characterization of related EPS profiles, the present work intends to clarify the comparative responses of Tetraselmis sp. to nonylphenol (NP), bisphenol A (BPA) and 17α-ethinylestradiol (EE2). The results showed that the half inhibitory concentration on cell growth was 0.190-0.313 mg/dm3 for NP, which was one order of magnitude lower than the comparable values for BPA and EE2 at 2.072-3.254 mg/dm3. Regarding chlorophyll, NP induced its degradation, EE2 led to its decreased production, and BPA had no obvious effect. Under EDC stress, only the concentrations of colloidal polysaccharides and proteins responded dose-dependently to EE2. Except for the colloidal fraction in the EE2 treatment group, the increase in neutral monosaccharides, especially glucose and galactose, was a common response to EDCs. Compared to the recalcitrant BPA, NP underwent abiotic degradation in alga-free water, and EE2 could be biodegraded in water containing this microalga. The chemical-specific responses of cell growth, chlorophyll and related EPS profiles were driven by the different fates of EDCs, and the underlying mechanism was further discussed. The results obtained in the present work are of critical importance for understanding the fate and effects of different EDCs mediated by microalgae and their related EPSs.
Collapse
Affiliation(s)
- Qian Yang
- Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University, Guangzhou, 510275, China; State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510600, China
| | - Weihao Xu
- Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Tiangang Luan
- State Key Laboratory of Biocontrol, South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Tianle Pan
- Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University, Guangzhou, 510275, China; State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510600, China
| | - Lihua Yang
- Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University, Guangzhou, 510275, China.
| | - Li Lin
- State Key Laboratory of Biocontrol, South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China.
| |
Collapse
|
11
|
Laviale M, Beaussart A, Allen J, Quilès F, El-Kirat-Chatel S. Probing the Adhesion of the Common Freshwater Diatom Nitzschia palea at Nanoscale. ACS APPLIED MATERIALS & INTERFACES 2019; 11:48574-48582. [PMID: 31766843 DOI: 10.1021/acsami.9b17821] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Freshwater biofilms play an essential ecological role, but they also adversely affect human activities through undesirable biofouling of artificial submerged structures. They form complex aggregates of microorganisms that colonize any type of substratum. In phototrophic biofilms, diatoms dominate in biomass and produce copious amount of extracellular polymeric substances (EPSs), making them efficient early colonizers. Therefore, a better understanding of diatoms adhesive properties is essential to develop new anti-biofouling strategies. In this context, we used atomic force microscopy (AFM) to decipher the topography and adhesive mechanisms of the common freshwater diatom Nitzschia palea. Images taken in physiological conditions revealed typical ultrastructural features with a few nanometers resolution. Using single-cell force spectroscopy, we showed that N. palea strongly adheres to hydrophobic surfaces as compared to hydrophilic ones. Chemical force spectroscopy with hydrophobic tips further confirmed that the adhesion is governed by surface-associated hydrophobic EPS distributed in clusters at the frustule surface, and mostly composed of (glyco)-lipids as revealed by Raman spectroscopy. Collectively, our results demonstrate that AFM-based nanoscopy, combined with Raman spectroscopy, is a powerful tool to provide new insights into the adhesion mechanisms of diatoms.
Collapse
Affiliation(s)
- Martin Laviale
- Université de Lorraine, CNRS, LIEC , F-57000 Metz , France
| | | | - Joey Allen
- Université de Lorraine, CNRS, LIEC , F-57000 Metz , France
| | - Fabienne Quilès
- Université de Lorraine, CNRS, LCPME , F-54000 Nancy , France
| | | |
Collapse
|