Cellular and genetic mechanism of bacterial mercury resistance and their role in biogeochemistry and bioremediation

Priyadarshanee, Monika; Chatterjee, Suman; Rath, Sonalin; Dash, Hirak Ranjan; Das, Surajit

doi:10.1016/j.jhazmat.2021.126985

Cited by 71 publications

(42 citation statements)

References 202 publications

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“…The mer genomes and their cluster genes, in general, have played a crucial role in the current scenario of environmental contamination control mechanisms. This study agreed with the study conducted on biogeochemistry and bioremediation of mercury by bacteria [27].…”

Section: Discussionsupporting

confidence: 92%

In Silico Study of Mercury Resistance Genes Extracted from Pseudomonas spp. Involved in Bioremediation: Understanding the Promoter Regions and Regulatory Elements

Dibbisa

Wagari²

2022

International Journal of Genomics

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Microbial genes and their product were diverse and beneficial for heavy metal bioremediation from the contaminated sites. Screening of genes and gene products plays a significant role in the detoxification of pollutants. Understanding of the promoter region and its regulatory elements is a vital implication of microbial genes. To the best of our knowledge, there is no in silico study reported so far on mer gene families used for heavy metal bioremediation. The motif distribution was observed densely upstream of the TSSs (transcription start sites) between +1 and -350 bp and sparsely distributed above -350 bp, according to the current study. MEME identified the best common candidate motifs of TFs (transcription factors) binding with the lowest e value (7.2 e -033) and is the most statistically significant candidate motif. The EXPREG output of the 11 TFs with varying degrees of function such as activation, repression, transcription, and dual purposes was thoroughly examined. Data revealed that transcriptional gene regulation in terms of activation and repression was observed at 36.4% and 54.56%, respectively. This shows that most TFs are involved in transcription gene repression rather than activation. Likewise, EXPREG output revealed that transcriptional conformational modes, such as monomers, dimers, tetramers, and other factors, were also analyzed. The data indicated that most of the transcriptional conformation mode was dual, which accounts for 96%. CpG island analysis using online and offline tools revealed that the gene body had fewer CpG islands compared to the promoter regions. Understanding the common candidate motifs, transcriptional factors, and regulatory elements of the mer operon gene cluster using a machine learning approach could help us better understand gene expression patterns in heavy metal bioremediation.

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Section: Discussionsupporting

confidence: 92%

In Silico Study of Mercury Resistance Genes Extracted from Pseudomonas spp. Involved in Bioremediation: Understanding the Promoter Regions and Regulatory Elements

Dibbisa

Wagari²

2022

International Journal of Genomics

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“…The bacterial mer operon plays a crucial role in the Hg biogeochemistry and bioremediation by converting both the reactive inorganic and organic forms of Hg to relatively inert, volatile, and monoatomic forms [ 43 ]. Consistent with previous studies [ 4 , 44 ], almost all of the identified HRGs (96.29%) were grouped into clusters, which indicates that HRGs tend to work together.…”

Section: Resultsmentioning

confidence: 99%

Plasmid Genomes Reveal the Distribution, Abundance, and Organization of Mercury-Related Genes and Their Co-Distribution with Antibiotic Resistant Genes in Gammaproteobacteria

Yang

Zhang

et al. 2022

Genes

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Mercury (Hg) pollution poses human health and environmental risks worldwide, as it can have toxic effects and causes selective pressure that facilitates the spread of antibiotic resistant genes (ARGs) among microbes. More and more studies have revealed that numerous Hg-related genes (HRGs) can help to resist and transform Hg. In the present study, we systematically analyzed the HRG distribution, abundance, organization, and their co-distribution with ARGs, using 18,731 publicly available plasmid genomes isolated from a Gammaproteobacteria host. Our results revealed that there were many Hg-resistant (mer) operon genes but they were not extensively distributed across plasmids, with only 9.20% of plasmids harboring HRGs. Additionally, no hgcAB genes (which methylate Hg to create methylmercury) were identified in any of the analyzed plasmids. The host source significantly influenced the number of HRGs harbored by plasmids; plasmids isolated from humans and animals harbored a significantly smaller number of HRGs than plasmids isolated from the wastewater and sludge. HRG clusters displayed an extremely high organizational diversity (88 HRG cluster types), though incidences of more than half of the HRG cluster types was <5. This indicates the frequent rearrangement among HRGs in plasmids. The 1368 plasmids harboring both HRGs and ARGs, were dominated by Klebsiella, followed by Escherichia, Salmonella, and Enterobacter. The tightness of the HRG and ARG co-distribution in plasmids was affected by the host sources but not by pathogenicity. HRGs were more likely to co-occur with specific ARG classes (sulfonamide, macrolide-lincosamide-streptogramin, and aminoglycoside resistance genes). Collectively, our results reveal the distribution characteristics of HRGs in plasmids, and they have important implications for further understanding the environmental risks caused by the spread of ARGs through the plasmid-mediated co-transfer of ARGs and HRGs.

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“…This same type of activity should likewise be expected for suspended planktonic bacteria/archaea cells and thereby, if not consumed, assist in stabilizing Hg bioavailability to higher elements of the food chain in lake pelagic zones in a role currently ascribed to humics (French et al, 2014; Haitzer et al, 2003). Actually, Hg metabolic capacity is quite widespread among bacteria and archaea lineages (Christakis et al, 2021; Priyadarshanee et al, 2022), including bioaccumulation activity. Indeed, pure culture studies have documented significant bacterial uptake and accumulation of Hg (see Dranguet, Le Faucheur, Cosio, et al, 2017; Durand et al, 2020; Giovanella et al, 2017; Kiyono et al, 2003; Sayler et al, 1975; Zhang et al, 2020), with Hg bioaccumulation in some bacteria registering in the grams per liter range (Kis et al, 2017; Zhang et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

Arsenic and Mercury Distribution in an Aquatic Food Chain: Importance of Femtoplankton and Picoplankton Filtration Fractions

Alowaifeer

Clingenpeel

Kan

et al. 2022

Enviro Toxic and Chemistry

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Arsenic (As) and mercury (Hg) were examined in the Yellowstone Lake food chain, focusing on two lake locations separated by approximately 20 km and differing in lake floor hydrothermal vent activity. Sampling spanned from femtoplankton to the main fish species, Yellowstone cutthroat trout and the apex predator lake trout. Mercury bioaccumulated in muscle and liver of both trout species, biomagnifying with age, whereas As decreased in older fish, which indicates differential exposure routes for these metal(loid)s. Mercury and As concentrations were higher in all food chain filter fractions (0.1‐, 0.8‐, and 3.0‐μm filters) at the vent‐associated Inflated Plain site, illustrating the impact of localized hydrothermal inputs. Femtoplankton and picoplankton size biomass (0.1‐ and 0.8‐μm filters) accounted for 30%–70% of total Hg or As at both locations. By contrast, only approximately 4% of As and <1% of Hg were found in the 0.1‐μm filtrate, indicating that comparatively little As or Hg actually exists as an ionic form or intercalated with humic compounds, a frequent assumption in freshwaters and marine waters. Ribosomal RNA (18S) gene sequencing of DNA derived from the 0.1‐, 0.8‐, and 3.0‐μm filters showed significant eukaryote biomass in these fractions, providing a novel view of the femtoplankton and picoplankton size biomass, which assists in explaining why these fractions may contain such significant Hg and As. These results infer that femtoplankton and picoplankton metal(loid) loads represent aquatic food chain entry points that need to be accounted for and that are important for better understanding Hg and As biochemistry in aquatic systems. Environ Toxicol Chem 2023;42:225–241. © 2022 SETAC

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Cellular and genetic mechanism of bacterial mercury resistance and their role in biogeochemistry and bioremediation

Cited by 71 publications

References 202 publications

In Silico Study of Mercury Resistance Genes Extracted from Pseudomonas spp. Involved in Bioremediation: Understanding the Promoter Regions and Regulatory Elements

In Silico Study of Mercury Resistance Genes Extracted from Pseudomonas spp. Involved in Bioremediation: Understanding the Promoter Regions and Regulatory Elements

Plasmid Genomes Reveal the Distribution, Abundance, and Organization of Mercury-Related Genes and Their Co-Distribution with Antibiotic Resistant Genes in Gammaproteobacteria

Arsenic and Mercury Distribution in an Aquatic Food Chain: Importance of Femtoplankton and Picoplankton Filtration Fractions

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