Food Plants and Environmental Contamination: An Update.

Food plants are the basis of human nutrition, but, in contaminated places, they can uptake contaminants. Environmental contamination and climate change can modify food quality; generally, they have a negative impact on and imply risks to human health. Heavy metals, like lead, arsenic, cadmium, and chromium, can be present at various environmental levels (soil, water, and atmosphere), and they are widely distributed in the world. Food plants can carry out heavy metal bioaccumulation, a defense pathway for plants, which is different for every plant species. Accumulation is frequent in the roots and the leaves, and heavy metals can be present in fruits and seeds; As and Cd are always present. In addition, other contaminants can bioaccumulate in food plants, including emerging contaminants, like persistent organic pollutants (POPs), pesticides, and microplastics. In food plants, these are present in the roots but also in the leaves and fruits, depending on their chemical structure. The literature published in recent years was examined to understand the distribution of contaminants among food plants. In the literature, old agronomical practices and new integrated technology to clean the water, control the soil, and monitor the crops have been proposed to mitigate contamination and produce high food quality and high food safety.

Biofilm and Rivers: The Natural Association to Reduce Metals in Waters.

This article focuses on a very peculiar habitat, the thin biofilm that covers the surface of rocks, cobbles, sediment grains, leaf litter, and vegetation on a riverbed. Species composition changes over time and depends on environmental conditions and perturbation of water quality. It provides several ecosystem services, contributing to the biogeochemical fluxes and reducing contamination by absorbing the pollutants. Biofilm into the Toce River (Ossola Valley, Piedmont, Italy) was investigated to assess its capacity to accumulate the metals and macroions from the water column. In this preliminary work, we investigated three sample points, in two different seasons. The community composition of biofilm was determined via morphological analysis (diatoms and non-diatoms algal community). We characterize the biofilm, a community of different organisms, from different perspectives. In the biofilm, Hg was analyzed with an automated mercury analyzer, other metals and macroions with inductively coupled plasma mass spectrometry (ICP-MS) (Al, As, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Ni, P, Pb, and Zn), and the carotenoid and chlorophyll composition of the photosynthetic organism with HPLC analysis for the primary producers. The results evidence a seasonal pattern in metals and macroions levels in the biofilm, and a significant difference in the biofilm community and in carotenoid composition, suggesting the utility of using the biofilm as an additional bioindicator to monitor the water quality of the river.

An Integrated Investigation of Atmospheric Gaseous Elemental Mercury Transport and Dispersion Around a Chlor-Alkali Plant in the Ossola Valley (Italian Central Alps).

We present the first assessment of atmospheric pollution by mercury (Hg) in an industrialized area located in the Ossola Valley (Italian Central Alps), in close proximity to the Toce River. The study area suffers from a level of Hg contamination due to a Hg cell chlor-alkali plant operating from 1915 to the end of 2017. We measured gaseous elemental Hg (GEM) levels by means of a portable Hg analyzer during car surveys between autumn 2018 and summer 2020. Moreover, we assessed the long-term dispersion pattern of atmospheric Hg by analyzing the total Hg concentration in samples of lichens collected in the Ossola Valley. High values of GEM concentrations (1112 ng m-3) up to three orders of magnitude higher than the typical terrestrial background concentration in the northern hemisphere were measured in the proximity of the chlor-alkali plant. Hg concentrations in lichens ranged from 142 ng g-1 at sampling sites located north of the chlor-alkali plant to 624 ng g-1 in lichens collected south of the chlor-alkali plant. A north-south gradient of Hg accumulation in lichens along the Ossola Valley channel was observed, highlighting that the area located south of the chlor-alkali plant is more exposed to the dispersion of Hg emitted into the atmosphere from the industrial site. Long-term studies on Hg emission and dispersion in the Ossola Valley are needed to better assess potential impact on ecosystems and human health.

Biochemical aspects of seeds from Cannabis sativa L. plants grown in a mountain environment.

Cannabis sativa L. (hemp) is a versatile plant which can adapt to various environmental conditions. Hempseeds provide high quality lipids, mainly represented by polyunsaturated acids, and highly digestible proteins rich of essential aminoacids. Hempseed composition can vary according to plant genotype, but other factors such as agronomic and climatic conditions can affect the presence of nutraceutic compounds. In this research, seeds from two cultivars of C. sativa (Futura 75 and Finola) grown in a mountain environment of the Italian Alps were analyzed. The main purpose of this study was to investigate changes in the protein profile of seeds obtained from such environments, using two methods (sequential and total proteins) for protein extraction and two analytical approaches SDS-PAGE and 2D-gel electrophoresis, followed by protein identification by mass spectrometry. The fatty acids profile and carotenoids content were also analysed. Mountain environments mainly affected fatty acid and protein profiles of Finola seeds. These changes were not predictable by the sole comparison of certified seeds from Futura 75 and Finola cultivars. The fatty acid profile confirmed a high PUFA content in both cultivars from mountain area, while protein analysis revealed a decrease in the protein content of Finola seeds from the experimental fields.

ATR-FT/IR study on the interactions between gliadins and dextrin and their effects on protein secondary structure.

The effects of heat treatment and dextrin addition on the secondary structure of gliadins were investigated by means of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FT/IR). Gliadins and gliadin/dextrin mixtures (before and after thermal treatment) were prepared as a dried protein film on the ATR-FT/IR zinc selenide cell plate and equilibrated at a water activity (a(w)) of 0.06. The results show that gliadins undergo conformational changes upon thermal treatment both in the absence and in the presence of dextrin. In particular, in the thermally treated gliadins, the decrease of the band at around 1651 cm(-)(1) and the increase of the bands at around 1628 and 1690 cm(-)(1) suggest a loss of alpha-helix structure and a higher content of protein aggregates. The same trend was observed in the presence of dextrin. Concerning the interactions between gliadins and dextrin, gliadin/dextrin mixtures show variations in the amide I region compared to native gliadins (e.g., an increase of the band at 1645 cm(-)(1) and the absence of the band at around 1668 cm(-)(1)) that might be due to hydrogen bond formation between gliadins and dextrin. It was also found that the spectrum of gliadin/dextrin mixtures was less affected by the hydration state than that of native gliadins, as observed from the differential spectra obtained by subtraction of the spectrum obtained at a(w) = 0.06 (driest condition tested) from the spectrum of the sample equilibrated at a(w) = 0.84. This could be due to the fact that C=O and N-H groups of gliadins are engaged to form hydrogen bonds with the hydroxyl groups of dextrin, and so they are not perturbed by the presence of water molecules. Finally, water activity effects on the secondary structure of gliadins are also discussed.

Involvement of the Azotobacter vinelandii rhodanese-like protein RhdA in the glutathione regeneration pathway.

The phenotypic features of the Azotobacter vinelandii RhdA mutant MV474 (in which the rhdA gene was deleted) indicated that defects in antioxidant systems in this organism were related to the expression of the tandem-domain rhodanese RhdA. In this work, further insights on the effects of the oxidative imbalance generated by the absence of RhdA (e.g. increased levels of lipid hydroperoxides) are provided. Starting from the evidence that glutathione was depleted in MV474, and using both in silico and in vitro approaches, here we studied the interaction of wild-type RhdA and Cys(230)Ala site-directed RhdA mutant with glutathione species. We found that RhdA was able to bind in vitro reduced glutathione (GSH) and that RhdA-Cys(230) residue was mandatory for the complex formation. RhdA catalyzed glutathione-disulfide formation in the presence of a system generating the glutathione thiyl radical (GS, an oxidized form of GSH), thereby facilitating GSH regeneration. This reaction was negligible when the Cys(230)Ala RhdA mutant was used. The efficiency of RhdA as catalyst in GS-scavenging activity is discussed on the basis of the measured parameters of both interaction with glutathione species and kinetic studies.

Enzymatic and genetic profiles in environmental strains grown on polycyclic aromatic hydrocarbons.

The possible generation of oxidative stress induced by aromatic hydrocarbon degradation suggests that ancillary enzyme activities could facilitate the utilization of polycyclic aromatic hydrocarbons as sole carbon source. To investigate the metabolic profiles of low molecular weight polycyclic aromatic hydrocarbon-degrading strains of Sphingobium chlorophenolicum, Rhodococcus aetherovorans, Rhodococcus opacus and Mycobacterium smegmatis, the determination of the activity of putative detoxifying enzymes (rhodanese-like and glutathione S-transferase proteins) was combined with genetic analyses. All the studied strains were able to utilize phenanthrene or naphthalene. Glutathione S-transferase activity was found in S. chlorophenolicum strains grown on phenanthrene and it was related to the presence of the bphK gene, since modulation of glutathione S-transferase activity by phenanthrene paralleled the induction of glutathione S-transferase transcript in the S. chlorophenolicum strains. No glutathione S-transferase activity was detectable in R. aetherovorans, R. opacus and in M. smegmatis strains. All strains showed 3-mercaptopyruvate:cyanide sulfurtransferase activity. A rhodanese-like SseA protein was immunodetected in R. aetherovorans, R. opacus and in M. smegmatis strains, where increase of 3-mercaptopyruvate:cyanide sulfurtransferase activity was significantly induced by growth on phenanthrene.