Heavy metal tolerance of marine phytoplankton. IV. Combined effect of zinc and cadmium on growth and uptake in some marine diatoms

This study evaluates bacteriological profiles in ready-to-eat (RTE) foods and assesses antibiotic resistance, extended-spectrum β-lactamase (ESBL) production by gram-negative bacteria, and heavy metal tolerance. In total, 436 retail food samples were collected and cultured. The isolates were screened for ESBL production and molecular detection of ESBL-encoding genes. Furthermore, all isolates were evaluated for heavy metal tolerance. From 352 culture-positive samples, 406 g-negative bacteria were identified. Raw food samples were more often contaminated than refined food (84.71% vs. 76.32%). The predominant isolates were Klebsiella pneumoniae (n = 76), Enterobacter cloacae (n = 58), and Escherichia coli (n = 56). Overall, the percentage of ESBL producers was higher in raw food samples, although higher occurrences of ESBL-producing E. coli (p = 0.01) and Pseudomonas aeruginosa (p = 0.02) were observed in processed food samples. However, the prevalence of ESBL-producing Citrobacter freundii in raw food samples was high (p = 0.03). Among the isolates, 55% were blaCTX-M, 26% were blaSHV, and 19% were blaTEM. Notably, heavy metal resistance was highly prevalent in ESBL producers. These findings demonstrate that retail food samples are exposed to contaminants including antibiotics and heavy metals, endangering consumers.

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Evaluation of bacterial strains isolated from Late Quaternary alluvial sediments spanning ~ 28 m in depth for heavy metal tolerance and Cr(VI) removal ability

International Microbiology ◽

10.1007/s10123-021-00174-0 ◽

2021 ◽

Author(s):

Abhi P. Shah ◽

G. Archana

Keyword(s):

Heavy Metal ◽

Metal Tolerance ◽

Late Quaternary ◽

Heavy Metal Tolerance ◽

Bacterial Strains ◽

Alluvial Sediments

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Effect of Lead and Copper on Photosynthetic Apparatus in Citrus (Citrus aurantium L.) Plants. The Role of Antioxidants in Oxidative Damage as a Response to Heavy Metal Stress

Plants ◽

10.3390/plants10010155 ◽

2021 ◽

Vol 10 (1) ◽

pp. 155

Author(s):

Anastasia Giannakoula ◽

Ioannis Therios ◽

Christos Chatzissavvidis

Keyword(s):

Oxidative Stress ◽

Lipid Peroxidation ◽

Heavy Metal ◽

Metal Tolerance ◽

Heavy Metal Tolerance ◽

Membrane Integrity ◽

Photosynthetic Apparatus ◽

Heavy Metal Stress ◽

Photosynthetic Parameters ◽

Citrus Aurantium

Photosynthetic changes and antioxidant activity to oxidative stress were evaluated in sour orange (Citrus aurantium L.) leaves subjected to lead (Pb), copper (Cu) and also Pb + Cu toxicity treatments, in order to elucidate the mechanisms involved in heavy metal tolerance. The simultaneous effect of Pb− and Cu on growth, concentration of malondialdehyde (MDA), hydrogen peroxide (H2O2), chlorophylls, flavonoids, carotenoids, phenolics, chlorophyll fluorescence and photosynthetic parameters were examined in leaves of Citrus aurantium L. plants. Exogenous application of Pb and Cu resulted in an increase in leaf H2O2 and lipid peroxidation (MDA). Toxicity symptoms of both Pb and Cu treated plants were stunted growth and decreased pigments concentration. Furthermore, photosynthetic activity of treated plants exhibited a significant decline. The inhibition of growth in Pb and Cu-treated plants was accompanied by oxidative stress, as indicated by the enhanced lipid peroxidation and the high H2O2 concentration. Furthermore, antioxidants in citrus plants after exposure to high Pb and Cu concentrations were significantly increased compared to control and low Pb and Cu treatments. In conclusion, this study indicates that Pb and Cu promote lipid peroxidation, disrupt membrane integrity, reduces growth and photosynthesis and inhibit mineral nutrition. Considering the potential for adverse human health effects associated with high concentrations of Pb and Cu contained in edible parts of citrus plants the study signals that it is important to conduct further research into the accessibility and uptake of the tested heavy metals in the soil and whether they pose risks to humans.

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Molecular mechanistic model of plant heavy metal tolerance

BioMetals ◽

10.1007/s10534-012-9541-y ◽

2012 ◽

Vol 25 (3) ◽

pp. 489-505 ◽

Cited By ~ 61

Author(s):

Ganesh Thapa ◽

Ayan Sadhukhan ◽

Sanjib Kumar Panda ◽

Lingaraj Sahoo

Keyword(s):

Heavy Metal ◽

Metal Tolerance ◽

Mechanistic Model ◽

Heavy Metal Tolerance

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Intraspecific variation in metal tolerance modulate competition between two marine diatoms

The ISME Journal ◽

10.1038/s41396-021-01092-9 ◽

2021 ◽

Author(s):

Björn Andersson ◽

Anna Godhe ◽

Helena L. Filipsson ◽

Linda Zetterholm ◽

Lars Edler ◽

...

Keyword(s):

Competitive Advantage ◽

Dose Response ◽

Metal Tolerance ◽

Marine Phytoplankton ◽

Strain Selection ◽

Control Treatment ◽

Toxic Stress ◽

Marine Diatoms ◽

Toxic Dose ◽

Multiple Strains

AbstractDespite widespread metal pollution of coastal ecosystems, little is known of its effect on marine phytoplankton. We designed a co-cultivation experiment to test if toxic dose–response relationships can be used to predict the competitive outcome of two species under metal stress. Specifically, we took into account intraspecific strain variation and selection. We used 72 h dose–response relationships to model how silver (Ag), cadmium (Cd), and copper (Cu) affect both intraspecific strain selection and competition between taxa in two marine diatoms (Skeletonema marinoi and Thalassiosira baltica). The models were validated against 10-day co-culture experiments, using four strains per species. In the control treatment, we could predict the outcome using strain-specific growth rates, suggesting low levels of competitive interactions between the species. Our models correctly predicted which species would gain a competitive advantage under toxic stress. However, the absolute inhibition levels were confounded by the development of chronic toxic stress, resulting in a higher long-term inhibition by Cd and Cu. We failed to detect species differences in average Cu tolerance, but the model accounting for strain selection accurately predicted a competitive advantage for T. baltica. Our findings demonstrate the importance of incorporating multiple strains when determining traits and when performing microbial competition experiments.

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