Assessment of Biological Contribution to Natural Recovery of Anthropized Freshwater Sediments From Argentina: Autochthonous Microbiome Structure and Functional Prediction

Monitored natural recovery (MNR) is an in situ technique of conventional remediation for the treatment of contaminated sediments that relies on natural processes to reduce the bioavailability or toxicity of contaminants. Metabarcoding and bioinformatics approaches to infer functional prediction were applied in bottom sediments of a tributary drainage channel of Río de La Plata estuary, in order to assess the biological contribution to MNR. Hydrocarbon concentration in water samples and surface sediments was below the detection limit. Surface sediments were represented with high available phosphorous, alkaline pH, and the bacterial classes Anaerolineae, Planctomycetia, and Deltaproteobacteria. The functional prediction in surface sediments showed an increase of metabolic activity, carbon fixation, methanogenesis, and synergistic relationships between Archaeas, Syntrophobacterales, and Desulfobacterales. The prediction in non-surface sediments suggested the capacity to respond to different kinds of environmental stresses (oxidative, osmotic, heat, acid pH, and heavy metals), predicted mostly in Lactobacillales order, and the capacity of Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Actinomyces classes to degrade xenobiotic compounds. Canonical correspondence analysis (CCA) suggests that depth, phosphate content, redox potential, and pH were the variables that structured the bacterial community and not the hydrocarbons. The characterization of sediments by metabarcoding and functional prediction approaches, allowed to assess how the microbial activity would contribute to the recovery of the site.Centro de Investigación y Desarrollo en Fermentaciones Industriale

Utilisation de la luzerne pour le traitement par phytoremédiation assistée chimiquement et biologiquement de sols co-contaminés par des métaux lourds et des hydrocarbures pétroliers

General background: As a result of human activity, soil resources have been contaminated with heavy metals and petroleum hydrocarbons. The great number of co-contaminated soils in the environment shows just how important it is to find remediation solutions adequate in such complex scenarios, which had seldom been studied before. Phytoremediation is a biological remediation technology, which takes advantage of the intrinsic physiological abilities of plants to remediate contaminated media. Plants and their associated microorganisms perform phytoremediation processes (e.g. phytoextraction and rhizodegradation), which can bring about the clean-up of cocontaminated soils. However, a major constraint which hinders the success of phytotechnologies is low bioavailability of pollutants in soil. As a result, chemically and biologically assisted phytoremediation are possible strategies used to overcome this limitation and enhance the efficiency of remediation. The chemical approach presented in this study involves adding biodegradable soil amendments to increase the ability of contaminants for being transferred from soil to plants and microorganisms. The biological strategy explored herein consists of inoculating contaminated soils with bacteria (bioaugmentation) able to improve remediation of pollutants and/or promote plant features.Main objectives: a) investigating the phytoremediation potential of alfalfa (Medicago sativa L.) in co-contaminated soils b) studying the effects of the low molecular weight organic acid citric acid and the surfactant Tween® 80 on the phytoremediation process c) assisting phytoremediation with a bioaugmentation approach using Pseudomonas aeruginosa bacteria.Methodologies: Determining germination and mortality rates, assessing plant physiological parameters. Quantifying plant biomass, heavy metals in plants, total petroleum hydrocarbons (TPH) in soil, soil microbiological indicators. Calculating phytoremediation parameters.Remarkable results: Alfalfa presented low tolerance to TPH contaminated soil at 8400 mg kg-1 soil, which was improved when TPH were present at a lower rate of concentration (3600 mg kg-1 soil). Alfalfa was able to take up limited quantities of metals (<100 mg kg-1 dry matter), while it had a positive effect on promoting the microbial number of alkane degraders and lipase activity in the rhizosphere. Moreover, the combined application of citric acid and Tween® 80 resulted in a greater improvement of these parameters. Bioaugmentation with P. aeruginosa had a promoting effect on alfalfa biomass (71% increase of plant total dry biomass). In addition, the highest TPH removal rates (68%, after 90 days of experiment) were obtained in soils vegetated with alfalfa and bioaugmented with P. aeruginosa. Overall conclusion: Alfalfa can tolerate a heavy metal and petroleum hydrocarbon co-contaminated soil (subject to TPH levels), which is an essential characteristic of any plant species used in phytoremediation. Alfalfa could not be considered as an active heavy metal removal species as it was not able to phytoextract significant amounts of heavy metals (still in the presence of soil amendments or bioaugmentation). Nevertheless, the enhancement of microbial number and activity in the rhizosphere encouraged the potential of this plant species to be successfully used in the remediation of petroleum hydrocarbons. These effects were further enhanced by thejoint application of soil amendments. Finally, the combination of phytoremediation and bioaugmentation seems to be a promising approach to remediate petroleum hydrocarbons, when present in co-contaminated soils.Contexte general: En raison des activités anthropiques, les sols sont souvent contaminés par des métaux lourds et des hydrocarbures pétroliers. Le nombre important de sites co-contaminés dans l'environnement met en lumière la nécessité de trouver des solutions adéquates à ces scénarios complexes d'assainissement, qui, de plus, sont rarement étudiés. Parmi les techniques d’assainissement biologique, la phytoremédiation est une technique qui se base sur les propriétés naturelles des plantes pour assainir les sols. L’utilisation conjointe des plantes et des microorganismes pour dépolluer les sols co-contaminés est une stratégie de traitement en plein essor. Cependant, l’obstacle majeur qui entrave la réussite de tels traitements est la faible biodisponibilité des polluants dans le sol. Par conséquent, la phytoremédiation peut être assistée par des traitements chimiques et/ou biologiques afin de surmonter cette limitation et d'améliorer l'efficacité de l'assainissement. Dans cette étude, l'approche chimique implique l'ajout d'amendements biodégradables. Enfin, la stratégie biologique retenue dans ce travail est la bioaugmentation qui consiste à ajouter dans le sol des bactéries capables d'améliorer l'assainissement des polluants et/ou favoriser lacroissance des plantes.Principaux objectifs: a) Étudier le potentiel de la luzerne pour la phytoremédiation des sols co-contaminés, b) Étudier les effets de l’acide organique de faible poids moléculaire acide citrique et le tensioactif Tween® 80 sur le processus de phytoremédiation et c) Étudier l’effet de la bioaugmentation avec la bactérie Pseudomonas aeruginosa sur le processus de phytoremédiation.Méthodes: Détermination des taux de germination et de mortalité, évaluation des paramètres physiologiques des plantes. Quantification de la biomasse végétale, des métaux lourds dans les plantes, hydrocarbures pétroliers totaux (HCT) dans le sol, et indicateurs microbiologiques du sol. Calcul des paramètres de phytoremediation.Résultats remarquables: La luzerne a présenté une faible tolérance aux HCT du sol à 8400 mg kg-1 de matière sèche (MS). Celle-ci qui a été améliorée lorsque les HCT étaient présents à plus faible concentration (3600 mg kg-1 MS). La luzerne a été en mesure de prendre les métaux dans une proportion limitée (<100 mg kg-1 MS), tandis qu’elle a eu un effet positif sur le nombre de microorganismes du sol capables de dégrader les alcanes et sur l'activité de la lipase dans la rhizosphère. En outre, l'application combinée de l'acide citrique et du Tween® 80 a donné lieu à uneamélioration plus importante de nombre et de l'activité microbienne dans la rhizosphère. La bioaugmentation avec P. aeruginosa a eu un effet sur l’amélioration de la biomasse de luzerne (augmentation de la biomasse végétale sèche totale de 71%). En outre, les taux les plus élevés d'élimination des HCT (68%, après 90 jours d'expérience) ont été obtenues dans les sols plantés avec la luzerne et bioaugmentées par P. aeruginosa.Conclusion générale: La luzerne pourrait tolérer le sol co-contaminé par des métaux lourds et des hydrocarbures pétroliers, ce qui est une caractéristique essentielle en phytoremédiation. La luzerne ne peut cependant pas être considérée comme une espèce capable d'extraire activement les métaux lourds, même en présence d'amendements chimiques ou par bioaugmentation. Néanmoins, l’augmentation du nombre et de l'activité microbienne dans la rhizosphère a confirmé le potentiel de cette plante à être utilisée avec succès dans le traitement des hydrocarbures pétroliers. Ces effets ont été par ailleurs renforcés par l'application conjointe d'acide citrique et de Tween® 80. Enfin, la combinaison de la phytoremédiation et de la bioaugmentation semble une approche prometteuse pour réaliser l'assainissement des hydrocarbures pétroliers, lorsqu'ils sont présents dans des sols co-contaminés

Plant-Microbiome Interactions in Hydrocarbon-Contaminated Soils

The use of green remediation technologies (i.e., phytoremediation, bioremediation, mycoremediation) for the restoration of hydrocarbon-contaminated sites is one of the keys for sustainable development. These technologies rely on the joint action of biotic components of the ecosystem, namely, plants, bacteria, and fungi. Despite the fact that previous studies showed that the clean-up of hydrocarbons could be achieved individually by plants or microorganisms, present investigations suggest that the interaction of plants with their surrounding microbiome determines the outcomes of green remediation technologies. This book chapter reviews the state of the art to explain the two-way relationship established between plants and their associated microbiome in hydrocarbon-polluted soils. Special focus is put on stressing the results obtained in recent studies that employ omics approaches.Centro de Investigación y Desarrollo en Fermentaciones IndustrialesConsejo Nacional de Investigaciones Científicas y TécnicasComisión de Investigaciones Científicas de la provincia de Buenos Aire

Impact of pyrometallurgical slags on sunflower growth, metal accumulation and rhizosphere microbial communities

Metallurgical exploitation originates metal-rich by-products termed slags, which are often disposed in the environment being a source of heavy metal pollution. Despite the environmental risk that this may pose for living organisms, little is known about the impact of slags on biotic components of the ecosystem like plants and rhizosphere microbial communities. In this study, metal-rich (Cu, Pb, Zn) granulated slags (GS) derived from Cu production process, were used for a leaching test in the presence of the soil pore solution, showing that soil solution enhanced the release of Cu from GS. A pot experiment was conducted using as growing substrate for sunflower (Helianthus annuus) a 50% w/w mix of an agricultural soil and GS. Bioavailability of metals in soil was, in increasing order: Pb < Zn < Cu. Sunflower was able to grow in the presence of GS and accumulated metals preferentially in above-ground tissues. Microbial diversity was assessed in rhizosphere and bulk soil using community level physiological profiling (CLPP) and 16S rRNA gene based denaturing gradient gel electrophoresis (DGGE) analyses, which demonstrated a shift in the diversity of microbial communities induced by GS. Overall, these results suggest that metallurgical wastes should not be considered inert when dumped in the soil. Implications from this study are expected to contribute to the development of sustainable practices for the management of pyrometallurgical slags, possibly involving a phytomanagement approach.Fil: Agnello, Ana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina. Université Paris-Est. Laboratoire Géomatériaux et Environnement; FranciaFil: Potysz, A.. University of Wrocław.Institute of Geological Sciences; PoloniaFil: Fourdrin, C.. Université Paris-Est. Laboratoire Géomatériaux et Environnement; FranciaFil: Huguenot, D.. Université Paris-Est. Laboratoire Géomatériaux et Environnement; FranciaFil: Chauhan, P.S.. Council of Scientific and Industrial Research. National Botanical Research Institute; Indi

Phytotoxicity of citric acid and Tween 80® for potential use as soil amendments in assisted phytoremediation

International audienc

Enhanced Phytoremediation: A Review of Low Molecular Weight Organic Acids and Surfactants Used as Amendments

International audienceThe contamination of soils with inorganic and organic pollutants is a diffuse environmental issue of significant relevance. Phytoremediation has been proposed as an economically feasible and sustainable remediation technology even if low bioavailability of contaminants constitutes one of the main limitations restricting the success of phytotechnologies. To overcome this constraint the addition of biodegradable amendments has been recently proposed in alternative to synthetic ones. This article presents an overview of two types of biodegradable soil amendments: low molecular weight organic acids and surfactants, evaluating the feasibility of their application in the frame of soil remediation throughout enhanced phytoremediation

Direct and indirect impact of the bacterial strain Pseudomonas aeruginosa on the dissolution of synthetic Fe(III)- and Fe(II)-bearing basaltic glasses

International audienceThis study investigates the direct and indirect bacterial contributions that influence the dissolution of basaltic glass. In this regard, three different types of glasses – with or without Fe, in the reduced Fe(II) or oxidized Fe(III) states – were prepared on the basis of a simplified basaltic glass composition. In order to prevent the direct contact between the glasses and the model siderophore-producing strain Pseudomonas aeruginosa, the glass samples were isolated in dialysis bags and immersed at 25 °C and pH 6.5 in bacterial cultures. Throughout the dissolution experiments, the following parameters were monitored: determination of bacterial growth, quantification of siderophore (i.e. pyoverdine) production, microscopic observation of the glass surface and determination of dissolution kinetics.Isolating the glass from the bacterial suspension only triggered the biosynthesis of siderophores in the Fe(III)-bearing glass dissolution experiments. Siderophores were produced in the presence of Fe(II)-bearing and Fe-free glass, independently on the experimental setup. The siderophore production appeared to be either continuous in the absence of Fe (glass-free control, Fe-free glass dissolution experiments) or stopped as soon as the bacteria entered their stationary phase when an Fe source was present (Fe(II) and Fe(III)-bearing glass dissolution experiments). The increase in the dissolution rates of each glass was correlated to the complex stability constants of the siderophore with the metallic cations in presence (KFe2+ < KAl3+ ≪ KFe3+). Among the three glasses, only the Fe(III)-bearing one seemed to be significantly impacted by the dialysis process: its dissolution rate was doubled by isolating the glass grains from the cells. These results particularly allow to separate the impact of such bacterial exudates from physical contact effects: they showed the efficiency of pyoverdine in increasing the dissolution of an Fe(III)-bearing glass and evidenced that a direct bacterial cell attachment to the surface of such a glass results in a more moderate enhancement of its dissolution process. This work is a new contribution regarding the high affinity of microorganisms for basaltic glasses as an Fe-source. It highlights the role of Fe(III) accessibility upon the bacterial cells as a key parameter regulating their activity and their efficiency in accelerating the dissolution

Assessment of Biological Contribution to Natural Recovery of Anthropized Freshwater Sediments From Argentina: Autochthonous Microbiome Structure and Functional Prediction

Monitored natural recovery (MNR) is an in situ technique of conventional remediation for the treatment of contaminated sediments that relies on natural processes to reduce the bioavailability or toxicity of contaminants. Metabarcoding and bioinformatics approaches to infer functional prediction were applied in bottom sediments of a tributary drainage channel of Río de La Plata estuary, in order to assess the biological contribution to MNR. Hydrocarbon concentration in water samples and surface sediments was below the detection limit. Surface sediments were represented with high available phosphorous, alkaline pH, and the bacterial classes Anaerolineae, Planctomycetia, and Deltaproteobacteria. The functional prediction in surface sediments showed an increase of metabolic activity, carbon fixation, methanogenesis, and synergistic relationships between Archaeas, Syntrophobacterales, and Desulfobacterales. The prediction in non-surface sediments suggested the capacity to respond to different kinds of environmental stresses (oxidative, osmotic, heat, acid pH, and heavy metals), predicted mostly in Lactobacillales order, and the capacity of Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Actinomyces classes to degrade xenobiotic compounds. Canonical correspondence analysis (CCA) suggests that depth, phosphate content, redox potential, and pH were the variables that structured the bacterial community and not the hydrocarbons. The characterization of sediments by metabarcoding and functional prediction approaches, allowed to assess how the microbial activity would contribute to the recovery of the site.Fil: Madueño, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; ArgentinaFil: Starevich, Viviana Ayelen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; ArgentinaFil: Agnello, Ana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; ArgentinaFil: Coppotelli, Bibiana Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; ArgentinaFil: Laprida, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Vidal, Nuria Carolina. YPF - Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Di Marco, Pablo. YPF - Tecnología; ArgentinaFil: Oneto, Maria Elena. YPF - Tecnología; ArgentinaFil: del Panno, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; ArgentinaFil: Morelli, Irma Susana. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentin