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Microorganisms
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Microbial Stress Response to Toxic Metal(loid)s
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Microbial Stress Response to Toxic Metal(loid)s

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Environmental Microbiology".

Deadline for manuscript submissions: closed (31 July 2020) | Viewed by 13604

Special Issue Editor

Prof. Dr. Juan Carlos Gutiérrez

E-Mail Website
Guest Editor
Department of Genetics, Physiology and Microbiology, Faculty of Biology, Complutense University of Madrid, 28040 Madrid, Spain
Interests: microbial ecotoxicology; heavy metals; metallic nanoparticles; metallothioneins; gene expression regulation; biosensors; protozoa; ciliates
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Environmental pollutants can exert selective stresses on living organisms. Among environmental stressors, metal(loid)s are of special relevance as some of the most abundant, toxic, and persistent inorganic pollutants. Metal(loid) toxicity can arise from interaction with biomolecules, such as proteins or nucleic acids, whose native structure and function may be thereby altered. Likewise, metal(loid)s can produce oxidative stress giving rise to very toxic reactive oxygen species. Both, prokaryotic and eukaryotic microorganisms have evolved a range of mechanisms to reduce the metal(loid) toxicity, such as chelation or intracellular sequestration (bioaccumulation) of metal(loid) cations by specific oligopeptides (glutathione, phytochelatins) or proteins (metallothioneins), metal(loid) exclusion by blocking the usual access “gate” to the cell, metal(loid) exclusion by active export (efflux pump) from the cell, extracellular sequestration or biosorption (passive adsorption by extracellular polymers), metal(loid) biotransformation (redox chemistry or methylation), and/or bioprecipitation by excreted cellular metabolism products. In this Special Issue of Microorganisms, we invite you to send contributions concerning any aspect related with this topic, including genetic, physiological, molecular, and cell biology or ecological aspects of the microbial stress response to metal(loid)s.

Dr. Juan Carlos Gutiérrez
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Microorganisms is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Prokaryotic microorganisms
  • Eukaryotic microorganisms
  • Metal(loid)s
  • Stress
  • Phytochelatins
  • Metallothioneins
  • Biotransformation
  • Metabolism
  • Detoxification mechanisms
  • Oxidative stress
  • Adaptive response
  • Genetic
  • Molecular biology
  • Physiology

Published Papers (4 papers)

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Research

23 pages, 1564 KiB  
Article
Tetrahymena Glutathione Peroxidase Family: A Comparative Analysis of These Antioxidant Enzymes and Differential Gene Expression to Metals and Oxidizing Agents
by Liliana L. Cubas-Gaona, Patricia de Francisco, Ana Martín-González and Juan Carlos Gutiérrez
Microorganisms 2020, 8(7), 1008; https://doi.org/10.3390/microorganisms8071008 - 05 Jul 2020
Cited by 9 | Viewed by 2656
Abstract
In the present work, an extensive analysis of the putative glutathione peroxidases (GPx) of the eukaryotic microorganism model Tetrahymena thermophila is carried out. A comparative analysis with GPx present in other Tetrahymena species and other very taxonomically diverse ciliates is also performed. A [...] Read more.
In the present work, an extensive analysis of the putative glutathione peroxidases (GPx) of the eukaryotic microorganism model Tetrahymena thermophila is carried out. A comparative analysis with GPx present in other Tetrahymena species and other very taxonomically diverse ciliates is also performed. A majority of ciliate GPx have replaced the selenocysteine (Sec) by Cys in its catalytic center, so they can be considered as phospholipid hydroperoxide glutathione peroxidases (PHGPx). Selenocysteine insertion sequence (SECIS) elements have been detected in several ciliate GPx that do not incorporate Sec in their amino acid sequences, and conversely, in other ciliate GPx with Sec, no SECIS elements are detected. These anomalies are analyzed and discussed. From the phylogenetic analysis using the ciliate GPx amino acid sequences, the existence of extensive intra- and interspecific gene duplications that produced multiple GPx isoforms in each species is inferred. The ancestral character of the selenoproteins is also corroborated. The analysis by qRT-PCR of six selected T. thermophila GPx genes has shown a quantitative differential expression between them, depending on the stressor (oxidizing agents, apoptotic inducer or metals) and the time of exposure. Full article
(This article belongs to the Special Issue Microbial Stress Response to Toxic Metal(loid)s)
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18 pages, 2538 KiB  
Article
FurA-Dependent Microcystin Synthesis under Copper Stress in Microcystis aeruginosa
by Yuanyuan Chen, Jiaojiao Yin, Jin Wei and Xuezhen Zhang
Microorganisms 2020, 8(6), 832; https://doi.org/10.3390/microorganisms8060832 - 01 Jun 2020
Cited by 4 | Viewed by 2273
Abstract
Massive blooms of cyanobacteria frequently occur with microcystin (MC) production. Cyanobacteria are exposed to copper stresses such as copper algaecides which are often used to remove cyanobacterial blooms. However, copper increased the MC production of cyanobacteria, and the underlying mechanism remains unclear. The [...] Read more.
Massive blooms of cyanobacteria frequently occur with microcystin (MC) production. Cyanobacteria are exposed to copper stresses such as copper algaecides which are often used to remove cyanobacterial blooms. However, copper increased the MC production of cyanobacteria, and the underlying mechanism remains unclear. The present study investigated the relationship between copper exposure (0.5 and 3 µM) and MC synthesis in Microcystis aeruginosa PCC 7806. The study concluded that the content of intracellular MCs increased by nearly two times both in 0.5 and 3 µM copper. High-throughput RNA sequencing (RNA-seq) provided evidence that copper mainly attacked Fe–S clusters, with evidence of changes in iron, sulfur, iron uptake regulators (fur), glutaredoxins and dehydratase genes. The transcription of numbers of genes implicated in iron uptake, MC synthesis and furA was also evaluated with quantitative real-time PCR (qRT-PCR). In these three Cu treatment groups, the amount of MCs increased as copper elevated. As the expression of mcyD gene was directly regulated by FurA and copper ions affected the expression of the FurA-related genes, we believed that MC synthesis genes were controlled by copper. This study has made a further understanding of the mechanism of the increase in MC synthesis of M. aeruginosa PCC 7806 treated with copper-based algaecides. We aimed to understand the mechanism of copper ion influencing the synthesis of MCs. Full article
(This article belongs to the Special Issue Microbial Stress Response to Toxic Metal(loid)s)
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18 pages, 3260 KiB  
Article
Probing the Role of the Chloroplasts in Heavy Metal Tolerance and Accumulation in Euglena gracilis
by Bishal Khatiwada, Mafruha T. Hasan, Angela Sun, Karthik Shantharam Kamath, Mehdi Mirzaei, Anwar Sunna and Helena Nevalainen
Microorganisms 2020, 8(1), 115; https://doi.org/10.3390/microorganisms8010115 - 14 Jan 2020
Cited by 19 | Viewed by 3269
Abstract
The E. gracilis Zm-strain lacking chloroplasts, characterized in this study, was compared with the earlier assessed wild type Z-strain to explore the role of chloroplasts in heavy metal accumulation and tolerance. Comparison of the minimum inhibitory concentration (MIC) values indicated that both strains [...] Read more.
The E. gracilis Zm-strain lacking chloroplasts, characterized in this study, was compared with the earlier assessed wild type Z-strain to explore the role of chloroplasts in heavy metal accumulation and tolerance. Comparison of the minimum inhibitory concentration (MIC) values indicated that both strains tolerated similar concentrations of mercury (Hg) and lead (Pb), but cadmium (Cd) tolerance of the Z-strain was twice that of the Zm-strain. The ability of the Zm-strain to accumulate Hg was higher compared to the Z-strain, indicating the existence of a Hg transportation and accumulation mechanism not depending on the presence of chloroplasts. Transmission electron microscopy (TEM) showed maximum accumulation of Hg in the cytosol of the Zm-strain and highest accumulation of Cd in the chloroplasts of the Z-strain indicating a difference in the ability of the two strains to deposit heavy metals in the cell. The highly abundant heavy metal transporter MTP2 in the Z-strain may have a role in Cd transportation to the chloroplasts. A multidrug resistance-associated protein highly increased in abundance in the Zm-strain could be a potential Hg transporter to either cytosol or mitochondria. Overall, the chloroplasts appear to have major role in the tolerance and accumulation of Cd in E. gracilis. Full article
(This article belongs to the Special Issue Microbial Stress Response to Toxic Metal(loid)s)
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14 pages, 892 KiB  
Article
Enhanced Arsenic Tolerance in Triticum aestivum Inoculated with Arsenic-Resistant and Plant Growth Promoter Microorganisms from a Heavy Metal-Polluted Soil
by Javiera Soto, Javier Ortiz, Hector Herrera, Alejandra Fuentes, Leonardo Almonacid, Trevor C. Charles and César Arriagada
Microorganisms 2019, 7(9), 348; https://doi.org/10.3390/microorganisms7090348 - 12 Sep 2019
Cited by 40 | Viewed by 4684
Abstract
In soils multi-contaminated with heavy metal and metalloids, the establishment of plant species is often hampered due to toxicity. This may be overcome through the inoculation of beneficial soil microorganisms. In this study, two arsenic-resistant bacterial isolates, classified as Pseudomonas gessardii and Brevundimonas [...] Read more.
In soils multi-contaminated with heavy metal and metalloids, the establishment of plant species is often hampered due to toxicity. This may be overcome through the inoculation of beneficial soil microorganisms. In this study, two arsenic-resistant bacterial isolates, classified as Pseudomonas gessardii and Brevundimonas intermedia, and two arsenic-resistant fungi, classified as Fimetariella rabenhortii and Hormonema viticola, were isolated from contaminated soil from the Puchuncaví valley (Chile). Their ability to produce indoleacetic acid and siderophores and mediate phosphate solubilization as plant growth-promoting properties were evaluated, as well as levels of arsenic resistance. A real time PCR applied to Triticum aestivum that grew in soil inoculated with the bacterial and fungal isolates was performed to observe differences in the relative expression of heavy metal stress defense genes. The minimum inhibitory concentration of the bacterial strains to arsenate was up to 7000 mg·L−1 and that of the fungal strains was up to 2500 mg·L−1. P. gessardi was able to produce siderophores and solubilize phosphate; meanwhile, B. intermedia and both fungi produced indoleacetic acid. Plant dry biomass was increased and the relative expression of plant metallothionein, superoxide dismutase, ascorbate peroxidase and phytochelatin synthase genes were overexpressed when P. gessardii plus B. intermedia were inoculated. Full article
(This article belongs to the Special Issue Microbial Stress Response to Toxic Metal(loid)s)
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