18 research outputs found

    Land use in urban areas impacts the composition of soil bacterial communities involved in nitrogen cycling. A case study from Lefkosia (Nicosia) Cyprus

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    International audienceAbstract The different types of land-use and soil lithology in urban and peri-urban areas of modern cities compose a complex mosaic of soil ecosystems. It is largely unknown how these differences result in changes in bacterial community composition and structure as well as in functional guilds involved in N cycling. To investigate the bacterial composition and the proportion of denitrifiers in agricultural, forested, schoolyard and industrial areas, 24 samples were collected from urban and peri-urban sites of Lefkosia. Bacterial diversity and the proportion of denitrifiers were assessed by NGS and qPCR, respectively. Proteobacteria, Actinobacteria, Bacteriodetes, Chloroflexi, Acidobacteria and Planctomycetes were identified as the most dominant phyla across all sites, while agricultural sites exhibited the highest bacterial diversity. Heavy metals such as Co, Pb, V and Al were identified as key factors shaping bacterial composition in industrial and schoolyard sites, while the bacterial assemblages in agricultural and forested sites were associated with Ca. Variance partitioning analysis showed that 10.2% of the bacterial community variation was explained by land use management, 5.1% by chemical elements due to soil lithology, and 1.4% by sampling location. The proportion of denitrifiers varied with land use management. In industrial and schoolyard sites, the abundance of the nos ZII bacterial community increased while nir K abundance declined. Our data showed that land use and lithology have a moderate impact on the bacterial assemblages in urban and peri-urban areas of Lefkosia. As the nos ZII bacterial community is important to the N 2 O sink capacity of soils, it would be interesting to elucidate the factors contributing to the proliferation of the nos ZII clade in these soils

    Uptake of hexavalent chromium by tomato (Solanum lycopersicum L.) plants and mediated effects on their physiology and productivity, along with fruit quality and safety

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    Cr(VI) is known to induce hormesis in plants. Nevertheless, its effects on the quality of agricultural produce are poorly studied. In the present study, tomato (Solanum lycopersicum L.) plants were exposed to incremental Cr(VI) concentrations through irrigation with water containing K2Cr2O7 in escalating concentrations (0.05, 0.5, 1, 5 and 10 mg L−1), aiming at investigating potential mediated effects on (1) yield, (2) stress responses in leaves, (3) the biosafety of fruits and (4) the mediated alterations in tomato fruit quality attributes. Plants in all Cr(VI) treatments displayed similar phenotype, with no modulations in fruit setting. Plants irrigated with water containing 10 mg L-1 K2Cr2O7 had lower photosynthetic pigment concentration and suffered from oxidative stress in their leaves (evidenced by increased MDA and H2O2 content). Elevated Cr(VI) treatments (5 or 10 mg L-1 K2Cr2O7) resulted in the production of fruits with lower weight and smaller size, along with increased ripening index and soluble solids, lycopene, β-carotene and soluble carbohydrate (fructose, sucrose, total sugars) content. Alterations in fruit quality attributes were at least in part corroborated by the abundance of transcripts related to sucrose (SlSuSys, SlLin5, SlLin6, SlLin7) and carotenoid (SlZDS, SlCRTISO, SlbLCY) biosynthesis. The concentration of total Cr in all fruit samples was far below the maximum permissible limits, thus indicating safety for human consumption. Overall, results presented herein provide novel evidence that Cr(VI) can exert significant effects on the quality of agricultural produce at the biochemical and molecular level, indicating that Cr(VI)-contaminated water should be cautiously used after rigorous investigation

    Uptake of hexavalent chromium by Lactuca sativa and Triticum aestivum plants and mediated effects on their performance, linked with associated public health risks

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    Plants exposed to toxic Cr(VI) concentrations show reduced biomass production and yield. The present study examined (1) the impacts of increasing Cr(VI) exposure (0.05, 0.5, 1, 5 and 10 mg L-1 K2Cr2O7 in irrigation water) on the growth and development, yield, and stress physiology of two important crop species, such as wheat (Triticum aestivum L.) and lettuce (Lactuca sativa L.), and (2) the associated human health risks due to the consumption of these commodities. Plants in all Cr(VI) treatments preserved similar growth rates and phenotypes with control, untreated plants, with no remarkable modulations in biomass yield (fresh/dry weight, plant height, straw/grain weight). Grains harvested from plants exposed to all Cr(VI) treatments had increased size and 1000 grain weight, partially suggesting hormetic effect. Elevated K2Cr2O7 concentrations (5 and 10 mg L-1) resulted in increased photosynthetic pigments' levels in lettuce leaves. Lipid peroxidation and H2O2 content also revealed the absence of oxidative stress in lettuce plants. Non-carcinogenic (target hazard quotient) and carcinogenic risks from the consumption of these commodities grown under the conditions described in this study were found de minimis. However, more studies are needed in order to obtain more solid information on the safety of Cr(VI)-contaminated water irrigation
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