Effect of Nicotiana benthamiana exposed to long- or short-chain perfluoroalkyl substances: Levels, transfer and potential risk analysis

Background: Perfluoroalkyl substances (PFAS) can endanger human health through the food chain. However, the physiological mechanisms of crops exposed to PFAS are still unclear. Objectives: The physiology, phytotoxicity and accumulation of Solanaceae model crops Nicotiana benthamiana exposed to perfluorooctanoic acid (PFOA), hexafluoropropylene oxide-dimer acid (HFPO-DA) and their mixed contaminants have been studied. Results: (i) Biomass, relative electrical conductivity and catalase all decrease; (ii) Chlorophyll, peroxidase, hydrogen peroxide and malondialdehyde all increase; (iii) Superoxide dismutase and soluble sugar both increase and then decrease; (Ⅳ) The absorption and transport of K, Ca, Mg and Na are affected, particularly shoots; (V) PFOA has the highest toxicity and bioaccumulation. Conclusion: PFAS will damages the economic benefits of crops and people's health. So, its production and uses should be curtailed except for essential uses. Future direction: Substitute substances may be more harmful, so grouping strategies and evaluation framework should be established as soon as possible.

Highly Contaminated Marine Sediments Can Host Rare Bacterial Taxa Potentially Useful for Bioremediation

Coastal areas impacted by high anthropogenic pressures typically display sediment contamination by polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs). Microbial-based bioremediation represents a promising strategy for sediment reclamation, yet it frequently fails due to poor knowledge of the diversity and dynamics of the autochthonous microbial assemblages and to the inhibition of the target microbes in the contaminated matrix. In the present study, we used an integrated approach including a detailed environmental characterization, high-throughput sequencing and culturing to identify autochthonous bacteria with bioremediation potential in the sediments of Bagnoli-Coroglio (Gulf of Naples, Mediterranean Sea), a coastal area highly contaminated by PAHs, aliphatic hydrocarbons and HMs. The analysis of the benthic prokaryotic diversity showed that the distribution of the dominant taxon (Gammaproteobacteria) was mainly influenced by PAHs, As, and Cd concentrations. The other abundant taxa (including Alphaproteobacteria, Deltaproteobacteria, Bacteroidetes, Acidobacteria, Actinobacteria, NB1-j, Desulfobacterota, and Myxococcota) were mainly driven by sediment grain size and by Cu and Cr concentrations, while the rare taxa (i.e., each contributing <1%) by As and aliphatic hydrocarbons concentrations and by sediment redox potential. These results suggest a differential response of bacterial taxa to environmental features and chemical contamination and those different bacterial groups may be inhibited or promoted by different contaminants. This hypothesis was confirmed by culturing and isolating 80 bacterial strains using media highly enriched in PAHs, only nine of which were contextually resistant to high HM concentrations. Such resistant isolates represented novel Gammaproteobacteria strains affiliated to Vibrio, Pseudoalteromonas, and Agarivorans, which were only scarcely represented in their original assemblages. These findings suggest that rare but culturable bacterial strains resistant/tolerant to high levels of mixed contaminants can be promising candidates useful for the reclamation by bioaugmentation strategies of marine sediments that are highly contaminated with PAHs and HMs.