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

AbstractThe present study was conducted to determine the culturable bacterial profile from Kestopur canal (Kolkata, India) and analyze their heavy metal tolerance. In addition to daily sewage including solid and soluble wastes, a considerable load of toxic metals are released into this water body from industries, tanneries and agriculture, household as well as health sectors. Screening out microbes from such an environment was done keeping in mind their multifunctional application especially for bioremediation. Heavy metals are major environmental pollutants when present in high concentration in soil and show potential toxic effects on growth and development in plants and animals. Some edible herbs growing in the canal vicinity, and consumed by people, were found to harbour these heavy metals at sub-toxic levels. The bioconcentration factor of these plants being <1 indicates that they probably only absorb but not accumulate heavy metals. All the thirteen Grampositive bacteria isolated from these plants rhizosphere were found to tolerate high concentration of heavy metals like Co, Ni, Pb, Cr, Fe. Phylogenetic analysis of their 16S rDNA genes revealed that they belonged to one main taxonomic group — the Firmicutes. Seven of them were found to be novel with 92–95% sequence homology with known bacterial strains. Further microbiological analyses show that the alkaliphilic Bacillus weihenstephanensis strain IA1 and Exiguobacterium aestuarii strain CE1, with selective antibiotic sensitivity along with high Ni2+ and Cr6+ removal capabilities, respectively, can be prospective candidates for bioremediation.

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Heavy Metal Tolerance Exhibited by Bacterial Strains Sourced from Adyar River

Water Science and Technology Library - Urban Ecology, Water Quality and Climate Change ◽

10.1007/978-3-319-74494-0_17 ◽

2018 ◽

pp. 215-226

Author(s):

K. C. Ramya Devi ◽

Krishnan Mary Elizabeth Gnanambal ◽

Yesupatham Babu

Keyword(s):

Heavy Metal ◽

Metal Tolerance ◽

Heavy Metal Tolerance ◽

Bacterial Strains

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Role of Bacillus cereus in Improving the Growth and Phytoextractability of Brassica nigra (L.) K. Koch in Chromium Contaminated Soil

Molecules ◽

10.3390/molecules26061569 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1569

Author(s):

Nosheen Akhtar ◽

Noshin Ilyas ◽

Humaira Yasmin ◽

R. Z. Sayyed ◽

Zuhair Hasnain ◽

...

Keyword(s):

Heavy Metal ◽

Seed Germination ◽

Plant Growth ◽

Bacillus Cereus ◽

Contaminated Soil ◽

Metal Tolerance ◽

Heavy Metal Tolerance ◽

Bacterial Strains ◽

Bacterial Inoculation ◽

Phytoextraction Potential

Plant growth-promoting rhizobacteria (PGPR) mediate heavy metal tolerance and improve phytoextraction potential in plants. The present research was conducted to find the potential of bacterial strains in improving the growth and phytoextraction abilities of Brassica nigra (L.) K. Koch. in chromium contaminated soil. In this study, a total of 15 bacterial strains were isolated from heavy metal polluted soil and were screened for their heavy metal tolerance and plant growth promotion potential. The most efficient strain was identified by 16S rRNA gene sequencing and was identified as Bacillus cereus. The isolate also showed the potential to solubilize phosphate and synthesize siderophore, phytohormones (indole acetic acid, cytokinin, and abscisic acid), and osmolyte (proline and sugar) in chromium (Cr+3) supplemented medium. The results of the present study showed that chromium stress has negative effects on seed germination and plant growth in B. nigra while inoculation of B. cereus improved plant growth and reduced chromium toxicity. The increase in seed germination percentage, shoot length, and root length was 28.07%, 35.86%, 19.11% while the fresh and dry biomass of the plant increased by 48.00% and 62.16%, respectively, as compared to the uninoculated/control plants. The photosynthetic pigments were also improved by bacterial inoculation as compared to untreated stress-exposed plants, i.e., increase in chlorophyll a, chlorophyll b, chlorophyll a + b, and carotenoid was d 25.94%, 10.65%, 20.35%, and 44.30%, respectively. Bacterial inoculation also resulted in osmotic adjustment (proline 8.76% and sugar 28.71%) and maintained the membrane stability (51.39%) which was also indicated by reduced malondialdehyde content (59.53% decrease). The antioxidant enzyme activities were also improved to 35.90% (superoxide dismutase), 59.61% (peroxide), and 33.33% (catalase) in inoculated stress-exposed plants as compared to the control plants. B. cereus inoculation also improved the uptake, bioaccumulation, and translocation of Cr in the plant. Data showed that B. cereus also increased Cr content in the root (2.71-fold) and shoot (4.01-fold), its bioaccumulation (2.71-fold in root and 4.03-fold in the shoot) and translocation (40%) was also high in B. nigra. The data revealed that B. cereus is a multifarious PGPR that efficiently tolerates heavy metal ions (Cr+3) and it can be used to enhance the growth and phytoextraction potential of B. nigra in heavy metal contaminated soil.

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Bacterial Tolerance to Heavy Metal Contents Present in Contaminated and Uncontaminated Soils

Bangladesh Journal of Microbiology ◽

10.3329/bjm.v29i2.28437 ◽

2016 ◽

Vol 29 (2) ◽

pp. 56-61

Author(s):

FZ Tanu ◽

S Hoque

Keyword(s):

Heavy Metal ◽

Bacillus Subtilis ◽

Bacillus Cereus ◽

Metal Tolerance ◽

Micrococcus Luteus ◽

Heavy Metal Tolerance ◽

Subtilis Strain ◽

Rrna Gene ◽

Bacterial Strains ◽

Metal Tolerant Bacteria

Present study dealt with identification of some heavy metal tolerant bacteria from contaminated industrial soils of Dhaka Export Processing Zone (DEPZ) at Savar, tannery area at Hazaribagh and uncontaminated agricultural soils of Dhamrai and Kushtia in Bangladesh and determination of their tolerance to chromium (Cr6+) and cadmium (Cd2+). A total of 15 isolates from four soil samples were provisionally identified as different species of Bacillus, Micrococcus and Pseudomonas based on their morphological, physiological, and biochemical characteristics. Among them eight colonies were separated based on high level of heavy metal tolerance and identified at molecular level by PCR technique and 16S rRNA gene sequencing as Micrococcus luteus strain P43 (E4), Bacillus pocheonensis strain TR2-6 (T6), Bacillus megaterium strain H2 (T8), Bacillus amyloliquefaciens strain SCSAAB0007 (D10), Bacillus cereus isolate PGBw4 (D11), Bacillus cereus strain ES-4a1 (K12), Bacillus subtilis strain 1320, (K13), and Bacillus subtilis strain DP14 (K14). The Maximum Tolerable Concentration (MTC) of bacterial strains to Cr6+ and Cd2+ ranged between 250-1250 ?g/ml and 30-150 ?g/ml, respectively in nutrient broth medium. From the metal tolerance investigation Bacillus was found as the most heavy metal tolerant to both Cr6+ and Cd2+ among the three genera. The identified heavy metal tolerant bacteria could be useful for the bioremediation of heavy metal contaminated environment.Bangladesh J Microbiol, Volume 29, Number 2, Dec 2012, pp 56-61

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Characterization of bacterial communities associated with the exotic and heavy metal tolerant wetland plant Spartina alterniflora

Scientific Reports ◽

10.1038/s41598-020-75041-5 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Ying Yang ◽

Jian Ding ◽

Yulang Chi ◽

Jianjun Yuan

Keyword(s):

Heavy Metal ◽

Spartina Alterniflora ◽

Metal Tolerance ◽

Bacterial Species ◽

Heavy Metal Tolerance ◽

Acc Deaminase ◽

Heavy Metal Stress ◽

Bacterial Strains ◽

Invasion Mechanisms ◽

Biochemical Assays

Abstract Heavy metal pollution has seriously disrupted eco-balance and transformed estuaries into sewage depots. Quanzhou bay is a typical heavy metal-contaminated estuary, in which Spartina alterniflora has widely invaded. Plant-associated microbial communities are crucial for biogeochemical cycles, studies of which would be helpful to demonstrate the invasion mechanisms of plants. Meanwhile, they are indispensable to phytoremediation by enhancing the heavy metal tolerance of plants, facilitating heavy metal absorption rate and promoting growth of plants. In the present study, S. alterniflora-associated rhizo- and endobacterial communities from 3 experimental sites were investigated by 454-pyrosequencing. Heavy metal screening generated 16 culturable isolates, further biochemical assays suggested these clones possess various abilities such as phosphate solubilization, indole-3-acetic acid (IAA) production and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production to accelerate heavy metal uptake and growth of the host. This study revealed the bacterial community structures and characterized the predominant resident bacterial strains of S. alterniflora-associated rhizo- and endobacteria under heavy metal stress, and isolated several bacterial species with potential ecological function.

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Heavy Metal Tolerance Trend in Extended-Spectrum β-Lactamase Encoding Strains Recovered from Food Samples

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18094718 ◽

2021 ◽

Vol 18 (9) ◽

pp. 4718

Author(s):

Kashaf Junaid ◽

Hasan Ejaz ◽

Iram Asim ◽

Sonia Younas ◽

Humaira Yasmeen ◽

...

Keyword(s):

Heavy Metal ◽

Metal Tolerance ◽

Heavy Metal Tolerance ◽

Heavy Metal Resistance ◽

Metal Resistance ◽

Food Samples ◽

Esbl Production ◽

Extended Spectrum ◽

Retail Food ◽

Esbl Producers

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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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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