L'écotoxicologie microbienne: Une discipline en émergence qui répond à des questions environnementales contemporaine

International audienceThis special issue of ESPR is focused on microbial ecotoxicology. What is ‘microbial ecotoxicology'? It is a branch of science that studies both (i) the ecological impacts of chemical (synthetic or natural origin) or biological (toxic species) pollution at the microbial scale and on the various functions that they ensure in the ecosystems and (ii) the role of microbial communities in the ecodynamic of the pollutants (source, transfer, degradation, transformation). It is a multidisciplinary scientific endeavor at the crossroad between microbial ecology, microbial toxicology, physics and chemistry (Fig. 1). It responds to an increasing demand worldwide of the politics and society because of the threat on environmental and human health caused by intense anthropogenic activities. In the context of the Anthropocene, microbial ecotoxicology seeks not only to conduct fundamental researches to understand the impact of pollutants on microbial processes and vice versa but also to carry out applied researches to provide tools readily usable by the society to monitor the evolution of the quality of the environment and to restore polluted sites

Relative involvement of nitrate and nitrite reduction in the competitiveness of Pseudomonas fluorescens in the rhizosphere of maize under non-limiting nitrate conditions

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Effect of soil type and plant species on the fluorescent pseudomonads nitrate dissimilating community

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L'émergence de l'écotoxicologie microbienne: retour sur les deux premiers colloques organisés en France

EA ECOLDUR CT3International audienceMicroorganisms are ubiquitous in soil, air, and water ecosystems, where they are key players of ecosystem services. Microbial ecotoxicology is an emerging interdisciplinary area of research which aims at investigating the impact of human activities on the diversity, abundance, and activity of microorganisms. In return, the results of such investigations hold the promise to provide novel ways of assessing in a sensitive way the impacts of diverse environmental disturbances and subsequent ecosystem responses. Thus and although the term itself is yet rarely encountered in the scientific literature, microbial ecotoxicology already addresses an increasing political and societal demand. In the French scientific landscape, which often mimics the famous (but sometimes indigestible) “mille-feuilles” pastry, microbial ecotoxicologists are scattered across many different research centers belonging to different research organizations and universities. This research field has thus lacked any visibility and remained unorganized until now. Formal organization of scientific activities may be considered a typical “froggies” concern (or ailment). Nevertheless, it is rather surprising that scientific journals and significant international conferences specifically devoted to microbial ecotoxicology have been missing so far, especially considering the plethoric range of journals and congresses devoted to microbial ecology and ecotoxicology. With these considerations in mind, the idea of organizing the French research community of microbial ecologists around concepts of ecotoxicology made its way, with the aim of sharing the necessity to overcome artificial boundaries that prevent progress in this promising field

Pollution by anthropogenic microfibers in North-West Mediterranean Sea and efficiency of microfiber removal by a wastewater treatment plant

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Plastic litter in the oceans. Most of it has gone missing, but it might just be transformed… or transported

International audienceThe balance between the leakage and abundance of plastic in the world’s oceans remains a current topic of debate [1], which renders difficult the understanding of the cycle of plastic on Earth [2]. We discuss recent findings and their implications on the missing plastic waste paradigm

Evaluation and optimization of nucleic acid extraction methods for the molecular analysis of bacterial communities associated with corroded carbon steel

International audienceDifferent DNA and RNA extraction approaches were evaluated and protocols optimized on in situ corrosion products from carbon steel in marine environments. Protocols adapted from the PowerSoil DNA/RNA Isolation methods resulted in the best nucleic acid (NA) extraction performances (ie combining high NA yield, quality, purity, representativeness of microbial community and processing time efficiency). The PowerSoil RNA Isolation Kit was the only method which resulted in amplifiable RNA of good quality (ie intact 16S/23S rRNA). Sample homogenization and hot chemical (SDS) cell lysis combined with mechanical (bead-beating) lysis in presence of a DNA competitor (skim milk) contributed to improving substantially (around 23 times) the DNA yield of the PowerSoil DNA Isolation Kit. Apart from presenting NA extraction strategies for optimizing extraction parameters with corrosion samples from carbon steel, this study proposes DNA and RNA extraction procedures suited for comparative molecular analysis of total and active fractions of bacterial communities associated with carbon steel corrosion events, thereby contributing to improved MIC diagnosis and control

Impact of open-ocean convection on nutrients, phytoplankton biomass and activity

We describe the impact of an open-ocean convection event on nutrient budgets, carbon budget, elemental stoichiometry, phytoplankton biomass and activity in the Northwestern Mediterranean Sea (NWM). In the convective episode examined here we estimated an input of nutrients to the surface layer of 7.0, 8.0 and 0.4×108 mol of silicate, nitrate and phosphate, respectively. These quantities correspond to the annual nutrient input by river discharges and atmospheric depositions in the Gulf of Lion. Such nutrient input is sufficient to sustain new primary production from 46 to 63 g C m−2 y−1, which is the same order of magnitude found in the NWM open waters. Our results together with satellite data analysis, propose new scenarios that explain the origin of the spring phytoplankton bloom occurring in NWM