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Jung H, Jiang V, Su Z, Inaba Y, Khoury FF, Banta S. Overexpression of a Designed Mutant Oxyanion Binding Protein ModA/WtpA in Acidithiobacillus ferrooxidans for the Low pH Recovery of Molybdenum and Rhenium. JACS AU 2024; 4:2957-2965. [PMID: 39211588 PMCID: PMC11350598 DOI: 10.1021/jacsau.4c00296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 05/02/2024] [Accepted: 05/03/2024] [Indexed: 09/04/2024]
Abstract
Molybdenum and rhenium are critically important metals for a number of emerging technologies. We identified and characterized a molybdenum/tungsten transport protein (ModA/WtpA) of Acidithiobacillus ferrooxidans and demonstrated the binding of tungstate, molybdate, and chromate. We used computational design to expand the binding capabilities of the protein to include perrhenate. A disulfide bond was engineered into the binding pocket of ModA/WtpA to introduce a more favorable geometric coordination and surface charge distribution for oxyanion binding. The mutant protein experimentally demonstrated a 2-fold higher binding affinity for molybdate and 6-fold higher affinity for perrhenate. The overexpression of the wild-type and mutant ModA/WtpA proteins in A. ferrooxidans cells enhanced the innate tungstate, molybdate, and chromate binding capacities of the cells to up to 2-fold higher. In addition, the engineered cells expressing the mutant protein exhibited enhanced perrhenate binding, showing 5-fold and 2-fold higher binding capacities compared to the wild-type and ModA/WtpA-overexpressing cells, respectively. Furthermore, the engineered cell lines enhanced biocorrosion of stainless steel as well as the recovered valuable metals from an acidic wastewater generated from molybdenite processing. The improved binding efficiency for the oxyanion metals, along with the high selectivity over nontargeted metals under mixed metal environments, highlights the potential value of the engineered strains for practical microbial metal reclamation under low pH conditions.
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Affiliation(s)
- Heejung Jung
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New
York, New York 10027, United States
| | - Virginia Jiang
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New
York, New York 10027, United States
| | - Zihang Su
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New
York, New York 10027, United States
| | - Yuta Inaba
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New
York, New York 10027, United States
| | - Farid F. Khoury
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New
York, New York 10027, United States
| | - Scott Banta
- Department of Chemical Engineering, Columbia University, 500 West 120th Street, New
York, New York 10027, United States
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Sun J, He X, LE Y, Al-Tohamy R, Ali SS. Potential applications of extremophilic bacteria in the bioremediation of extreme environments contaminated with heavy metals. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 352:120081. [PMID: 38237330 DOI: 10.1016/j.jenvman.2024.120081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Revised: 12/31/2023] [Accepted: 01/07/2024] [Indexed: 02/04/2024]
Abstract
Protecting the environment from harmful pollutants has become increasingly difficult in recent decades. The presence of heavy metal (HM) pollution poses a serious environmental hazard that requires intricate attention on a worldwide scale. Even at low concentrations, HMs have the potential to induce deleterious health effects in both humans and other living organisms. Therefore, various strategies have been proposed to address this issue, with extremophiles being a promising solution. Bacteria that exhibit resistance to metals are preferred for applications involving metal removal due to their capacity for rapid multiplication and growth. Extremophiles are a special group of microorganisms that are capable of surviving under extreme conditions such as extreme temperatures, pH levels, and high salt concentrations where other organisms cannot. Due to their unique enzymes and adaptive capabilities, extremophiles are well suited as catalysts for environmental biotechnology applications, including the bioremediation of HMs through various strategies. The mechanisms of resistance to HMs by extremophilic bacteria encompass: (i) metal exclusion by permeability barrier; (ii) extracellular metal sequestration by protein/chelator binding; (iii) intracellular sequestration of the metal by protein/chelator binding; (iv) enzymatic detoxification of a metal to a less toxic form; (v) active transport of HMs; (vi) passive tolerance; (vii) reduced metal sensitivity of cellular targets to metal ions; and (viii) morphological change of cells. This review provides comprehensive information on extremophilic bacteria and their potential roles for bioremediation, particularly in environments contaminated with HMs, which pose a threat due to their stability and persistence. Genetic engineering of extremophilic bacteria in stressed environments could help in the bioremediation of contaminated sites. Due to their unique characteristics, these organisms and their enzymes are expected to bridge the gap between biological and chemical industrial processes. However, the structure and biochemical properties of extremophilic bacteria, along with any possible long-term effects of their applications, need to be investigated further.
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Affiliation(s)
- Jianzhong Sun
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China.
| | - Xing He
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Yilin LE
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China.
| | - Rania Al-Tohamy
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Sameh S Ali
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China; Botany Department, Faculty of Science, Tanta University, Tanta, 31527, Egypt.
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Ullrich SR, Fuchs H, Ashworth-Güth C. Electrochemical and structural characterization of recombinant respiratory proteins of the acidophilic iron oxidizer Ferrovum sp. PN-J47-F6 suggests adaptations to the acidic pH at protein level. Front Microbiol 2024; 15:1357152. [PMID: 38384274 PMCID: PMC10879576 DOI: 10.3389/fmicb.2024.1357152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Accepted: 01/23/2024] [Indexed: 02/23/2024] Open
Abstract
The tendency of the periplasmic redox proteins in acidophiles to have more positive redox potentials (Em) than their homologous counterparts in neutrophiles suggests an adaptation to acidic pH at protein level, since thermodynamics of electron transfer processes are also affected by acidic pH. Since this conclusion is mainly based on the electrochemical characterization of redox proteins from extreme acidophiles of the genus Acidithiobacillus, we aimed to characterize three recombinant redox proteins of the more moderate acidophile Ferrovum sp. PN-J47-F6. We applied protein film voltammetry and linear sweep voltammetry coupled to UV/Vis spectroscopy to characterize the redox behavior of HiPIP-41, CytC-18, and CytC-78, respectively. The Em-values of HiPIP-41 (571 ± 16 mV), CytC-18 (276 ± 8 mV, 416 ± 2 mV), and CytC-78 (308 ± 7 mV, 399 ± 7 mV) were indeed more positive than those of homologous redox proteins in neutrophiles. Moreover, our findings suggest that the adaptation of redox proteins with respect to their Em occurs more gradually in response to the pH, since there are also differences between moderate and more extreme acidophiles. In order to address structure function correlations in these redox proteins with respect to structural features affecting the Em, we conducted a comparative structural analysis of the Ferrovum-derived redox proteins and homologs of Acidithiobacillus spp. and neutrophilic proteobacteria. Hydrophobic contacts in the redox cofactor binding pockets resulting in a low solvent accessibility appear to be the major factor contributing to the more positive Em-values in acidophile-derived redox proteins. While additional cysteines in HiPIPs of acidophiles might increase the effective shielding of the [4Fe-4S]-cofactor, the tight shielding of the heme centers in acidophile-derived cytochromes is achieved by a drastic increase in hydrophobic contacts (A.f. Cyc41), and by a larger fraction of aromatic residues in the binding pockets (CytC-18, CytC-78).
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Affiliation(s)
- Sophie R. Ullrich
- Environmental Microbiology Group, Institute for Biological Sciences, TU Bergakademie Freiberg, Freiberg, Germany
- Biohydrometallurgy Group, Institute for Biological Sciences, TU Bergakademie Freiberg, Freiberg, Germany
| | - Helena Fuchs
- Biohydrometallurgy Group, Institute for Biological Sciences, TU Bergakademie Freiberg, Freiberg, Germany
| | - Charlotte Ashworth-Güth
- Salt and Mineral Chemistry Group, Institute for Inorganic Chemistry, TU Bergakademie Freiberg, Freiberg, Germany
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Mitchell SL, Kearns DB, Carlson EE. Penicillin-binding protein redundancy in Bacillus subtilis enables growth during alkaline shock. Appl Environ Microbiol 2024; 90:e0054823. [PMID: 38126750 PMCID: PMC10807460 DOI: 10.1128/aem.00548-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 11/13/2023] [Indexed: 12/23/2023] Open
Abstract
Penicillin-binding proteins (PBPs) play critical roles in cell wall construction, cell shape maintenance, and bacterial replication. Bacteria maintain a diversity of PBPs, indicating that despite their apparent functional redundancy, there is differentiation across the PBP family. Apparently-redundant proteins can be important for enabling an organism to cope with environmental stressors. In this study, we evaluated the consequence of environmental pH on PBP enzymatic activity in Bacillus subtilis. Our data show that a subset of PBPs in B. subtilis change activity levels during alkaline shock and that one PBP isoform is rapidly modified to generate a smaller protein (i.e., PBP1a to PBP1b). Our results indicate that a subset of the PBPs are favored for growth under alkaline conditions, while others are readily dispensable. Indeed, we found that this phenomenon could also be observed in Streptococcus pneumoniae, implying that it may be generalizable across additional bacterial species and further emphasizing the evolutionary benefit of maintaining many, seemingly-redundant periplasmic enzymes.IMPORTANCEMicrobes adapt to ever-changing environments and thrive over a vast range of conditions. While bacterial genomes are relatively small, significant portions encode for "redundant" functions. Apparent redundancy is especially pervasive in bacterial proteins that reside outside of the inner membrane. While conditions within the cytoplasm are carefully controlled, those of the periplasmic space are largely determined by the cell's exterior environment. As a result, proteins within this environmentally exposed region must be capable of functioning under a vast array of conditions, and/or there must be several similar proteins that have evolved to function under a variety of conditions. This study examines the activity of a class of enzymes that is essential in cell wall construction to determine if individual proteins might be adapted for activity under particular growth conditions. Our results indicate that a subset of these proteins are preferred for growth under alkaline conditions, while others are readily dispensable.
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Affiliation(s)
| | - Daniel B. Kearns
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Erin E. Carlson
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
- Departments of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, United States
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
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Ullrich SR, Fuchs H, Schlömann M. Shedding light on the electron transfer chain of a moderately acidophilic iron oxidizer: characterization of recombinant HiPIP-41, CytC-18 and CytC-78 derived from Ferrovum sp. PN-J47-F6. Res Microbiol 2024; 175:104088. [PMID: 37348744 DOI: 10.1016/j.resmic.2023.104088] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/07/2023] [Accepted: 06/07/2023] [Indexed: 06/24/2023]
Abstract
Efficient electron transfer from the donor to the acceptor couple presents a necessary requirement for acidophilic and neutrophilic iron oxidizers due to the low energy yield of aerobic ferrous iron oxidation. Involved periplasmic electron carriers are very diverse in these bacteria and show adaptations to the respective thermodynamic constraints such as a more positive redox potential reported for extreme acidophilic Acidithiobacillus spp. Respiratory chain candidates of moderately acidophilic members of the genus Ferrovum share similarities with both their neutrophilic iron oxidizing relatives and the more distantly related Acidithiobacillus spp. We examined our previous omics-based conclusions on the potential electron transfer chain in Ferrovum spp. by characterizing the three redox protein candidates CytC-18, CytC-78 and HiPIP-41 of strain PN-J47-F6 which were produced as recombinant proteins in Eschericha coli. UV/Vis-based redox assays suggested that HiPIP-41 has a very positive redox potential while redox potentials of CytC-18 and CytC-78 are more negative than their counterparts in Acidithiobacillus spp. Far Western dot blotting demonstrated interactions between all three recombinant redox proteins while redox assays showed the electron transfer from HiPIP-41 to either of the cytochromes. Altogether, CytC-18, CytC-78 and HiPIP-41 indeed represent very likely candidates of the electron transfer in Ferrovum sp. PN-J4-F6.
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Affiliation(s)
- Sophie R Ullrich
- TU Bergakademie Freiberg, Institute for Biological Sciences, Leipziger Strasse 29, Freiberg, Germany.
| | - Helena Fuchs
- TU Bergakademie Freiberg, Institute for Biological Sciences, Leipziger Strasse 29, Freiberg, Germany
| | - Michael Schlömann
- TU Bergakademie Freiberg, Institute for Biological Sciences, Leipziger Strasse 29, Freiberg, Germany
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Páez-Pérez ED, Hernández-Sánchez A, Alfaro-Saldaña E, García-Meza JV. Disorder and amino acid composition in proteins: their potential role in the adaptation of extracellular pilins to the acidic media, where Acidithiobacillus thiooxidans grows. Extremophiles 2023; 27:31. [PMID: 37848738 DOI: 10.1007/s00792-023-01317-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 09/26/2023] [Indexed: 10/19/2023]
Abstract
There are few biophysical studies or structural characterizations of the type IV pilin system of extremophile bacteria, such as the acidophilic Acidithiobacillus thiooxidans. We set out to analyze their pili-comprising proteins, pilins, because these extracellular proteins are in constant interaction with protons of the acidic medium in which At. thiooxidans grows. We used the web server Operon Mapper to analyze and identify the cluster codified by the minor pilin of At. thiooxidans. In addition, we carried an in-silico characterization of such pilins using the VL-XT algorithm of PONDR® server. Our results showed that structural disorder prevails more in pilins of At. thiooxidans than in non-acidophilic bacteria. Further computational characterization showed that the pilins of At. thiooxidans are significantly enriched in hydroxy (serine and threonine) and amide (glutamine and asparagine) residues, and significantly reduced in charged residues (aspartic acid, glutamic acid, arginine and lysine). Similar results were obtained when comparing pilins from other Acidithiobacillus and other acidophilic bacteria from another genus versus neutrophilic bacteria, suggesting that these properties are intrinsic to pilins from acidic environments, most likely by maintaining solubility and stability in harsh conditions. These results give guidelines for the application of extracellular proteins of acidophiles in protein engineering.
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Affiliation(s)
- Edgar D Páez-Pérez
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, 78210, San Luis Potosí, SLP, Mexico.
| | - Araceli Hernández-Sánchez
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, 78210, San Luis Potosí, SLP, Mexico.
| | - Elvia Alfaro-Saldaña
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, 78210, San Luis Potosí, SLP, Mexico
| | - J Viridiana García-Meza
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, 78210, San Luis Potosí, SLP, Mexico
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Beard S, Moya-Beltrán A, Silva-García D, Valenzuela C, Pérez-Acle T, Loyola A, Quatrini R. Pangenome-level analysis of nucleoid-associated proteins in the Acidithiobacillia class: insights into their functional roles in mobile genetic elements biology. Front Microbiol 2023; 14:1271138. [PMID: 37817747 PMCID: PMC10561277 DOI: 10.3389/fmicb.2023.1271138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 09/01/2023] [Indexed: 10/12/2023] Open
Abstract
Mobile genetic elements (MGEs) are relevant agents in bacterial adaptation and evolutionary diversification. Stable appropriation of these DNA elements depends on host factors, among which are the nucleoid-associated proteins (NAPs). NAPs are highly abundant proteins that bind and bend DNA, altering its topology and folding, thus affecting all known cellular DNA processes from replication to expression. Even though NAP coding genes are found in most prokaryotic genomes, their functions in host chromosome biology and xenogeneic silencing are only known for a few NAP families. Less is known about the occurrence, abundance, and roles of MGE-encoded NAPs in foreign elements establishment and mobility. In this study, we used a combination of comparative genomics and phylogenetic strategies to gain insights into the diversity, distribution, and functional roles of NAPs within the class Acidithiobacillia with a special focus on their role in MGE biology. Acidithiobacillia class members are aerobic, chemolithoautotrophic, acidophilic sulfur-oxidizers, encompassing substantial genotypic diversity attributable to MGEs. Our search for NAP protein families (PFs) in more than 90 genomes of the different species that conform the class, revealed the presence of 1,197 proteins pertaining to 12 different NAP families, with differential occurrence and conservation across species. Pangenome-level analysis revealed 6 core NAP PFs that were highly conserved across the class, some of which also existed as variant forms of scattered occurrence, in addition to NAPs of taxa-restricted distribution. Core NAPs identified are reckoned as essential based on the conservation of genomic context and phylogenetic signals. In turn, various highly diversified NAPs pertaining to the flexible gene complement of the class, were found to be encoded in known plasmids or, larger integrated MGEs or, present in genomic loci associated with MGE-hallmark genes, pointing to their role in the stabilization/maintenance of these elements in strains and species with larger genomes. Both core and flexible NAPs identified proved valuable as markers, the former accurately recapitulating the phylogeny of the class, and the later, as seed in the bioinformatic identification of novel episomal and integrated mobile elements.
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Affiliation(s)
- Simón Beard
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
| | - Ana Moya-Beltrán
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Santiago, Chile
| | - Danitza Silva-García
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - Cesar Valenzuela
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - Tomás Pérez-Acle
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Santiago, Chile
| | - Alejandra Loyola
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
| | - Raquel Quatrini
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
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Izquierdo-Fiallo K, Muñoz-Villagrán C, Orellana O, Sjoberg R, Levicán G. Comparative genomics of the proteostasis network in extreme acidophiles. PLoS One 2023; 18:e0291164. [PMID: 37682893 PMCID: PMC10490939 DOI: 10.1371/journal.pone.0291164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 08/23/2023] [Indexed: 09/10/2023] Open
Abstract
Extreme acidophiles thrive in harsh environments characterized by acidic pH, high concentrations of dissolved metals and high osmolarity. Most of these microorganisms are chemolithoautotrophs that obtain energy from low redox potential sources, such as the oxidation of ferrous ions. Under these conditions, the mechanisms that maintain homeostasis of proteins (proteostasis), as the main organic components of the cells, are of utmost importance. Thus, the analysis of protein chaperones is critical for understanding how these organisms deal with proteostasis under such environmental conditions. In this work, using a bioinformatics approach, we performed a comparative genomic analysis of the genes encoding classical, periplasmic and stress chaperones, and the protease systems. The analysis included 35 genomes from iron- or sulfur-oxidizing autotrophic, heterotrophic, and mixotrophic acidophilic bacteria. The results showed that classical ATP-dependent chaperones, mostly folding chaperones, are widely distributed, although they are sub-represented in some groups. Acidophilic bacteria showed redundancy of genes coding for the ATP-independent holdase chaperones RidA and Hsp20. In addition, a systematically high redundancy of genes encoding periplasmic chaperones like HtrA and YidC was also detected. In the same way, the proteolytic ATPase complexes ClpPX and Lon presented redundancy and broad distribution. The presence of genes that encoded protein variants was noticeable. In addition, genes for chaperones and protease systems were clustered within the genomes, suggesting common regulation of these activities. Finally, some genes were differentially distributed between bacteria as a function of the autotrophic or heterotrophic character of their metabolism. These results suggest that acidophiles possess an abundant and flexible proteostasis network that protects proteins in organisms living in energy-limiting and extreme environmental conditions. Therefore, our results provide a means for understanding the diversity and significance of proteostasis mechanisms in extreme acidophilic bacteria.
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Affiliation(s)
- Katherin Izquierdo-Fiallo
- Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile (USACH), Santiago, Chile
| | - Claudia Muñoz-Villagrán
- Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile (USACH), Santiago, Chile
| | - Omar Orellana
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Rachid Sjoberg
- Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile (USACH), Santiago, Chile
| | - Gloria Levicán
- Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile (USACH), Santiago, Chile
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Mitchell SL, Kearns DB, Carlson EE. Penicillin-binding protein redundancy in Bacillus subtilis enables growth during alkaline shock. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.20.533529. [PMID: 36993441 PMCID: PMC10055284 DOI: 10.1101/2023.03.20.533529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Penicillin-binding proteins (PBPs) play critical roles in cell wall construction, cell shape, and bacterial replication. Bacteria maintain a diversity of PBPs, indicating that despite their apparent functional redundancy, there is differentiation across the PBP family. Seemingly redundant proteins can be important for enabling an organism to cope with environmental stressors. We sought to evaluate the consequence of environmental pH on PBP enzymatic activity in Bacillus subtilis. Our data show that a subset of B. subtilis PBPs change activity levels during alkaline shock and that one PBP isoform is rapidly modified to generate a smaller protein (i.e., PBP1a to PBP1b). Our results indicate that a subset of the PBPs are preferred for growth under alkaline conditions, while others are readily dispensable. Indeed, we found that this phenomenon could also be observed in Streptococcus pneumoniae, implying that it may be generalizable across additional bacterial species and further emphasizing the evolutionary benefit of maintaining many, seemingly redundant periplasmic enzymes.
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Affiliation(s)
| | - Daniel B. Kearns
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Erin E. Carlson
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
- Departments of Medicinal Chemistry, Biochemistry, Molecular Biology and Biophysics, and Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455
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Zhong YW, Zhou P, Cheng H, Zhou YD, Pan J, Xu L, Li M, Tao CH, Wu YH, Xu XW. Metagenomic Features Characterized with Microbial Iron Oxidoreduction and Mineral Interaction in Southwest Indian Ridge. Microbiol Spectr 2022; 10:e0061422. [PMID: 36286994 PMCID: PMC9769843 DOI: 10.1128/spectrum.00614-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 07/25/2022] [Indexed: 01/05/2023] Open
Abstract
The Southwest Indian Ridge (SWIR) is one of the typical representatives of deep-sea ultraslow-spreading ridges, and has increasingly become a hot spot of studying subsurface geological activities and deep-sea mining management. However, the understanding of microbial activities is still limited on active hydrothermal vent chimneys in SWIR. In this study, samples from an active black smoker and a diffuse vent located in the Longqi hydrothermal region were collected for deep metagenomic sequencing, which yielded approximately 290 GB clean data and 295 mid-to-high-quality metagenome-assembled genomes (MAGs). Sulfur oxidation conducted by a variety of Gammaproteobacteria, Alphaproteobacteria, and Campylobacterota was presumed to be the major energy source for chemosynthesis in Longqi hydrothermal vents. Diverse iron-related microorganisms were recovered, including iron-oxidizing Zetaproteobacteria, iron-reducing Deferrisoma, and magnetotactic bacterium. Twenty-two bacterial MAGs from 12 uncultured phyla harbored iron oxidase Cyc2 homologs and enzymes for organic carbon degradation, indicated novel chemolithoheterotrophic iron-oxidizing bacteria that affected iron biogeochemistry in hydrothermal vents. Meanwhile, potential interactions between microbial communities and chimney minerals were emphasized as enriched metabolic potential of siderophore transportation, and extracellular electron transfer functioned by multi-heme proteins was discovered. Composition of chimney minerals probably affected microbial iron metabolic potential, as pyrrhotite might provide more available iron for microbial communities. Collectively, this study provides novel insights into microbial activities and potential mineral-microorganism interactions in hydrothermal vents. IMPORTANCE Microbial activities and interactions with minerals and venting fluid in active hydrothermal vents remain unclear in the ultraslow-spreading SWIR (Southwest Indian Ridge). Understanding about how minerals influence microbial metabolism is currently limited given the obstacles in cultivating microorganisms with sulfur or iron oxidoreduction functions. Here, comprehensive descriptions on microbial composition and metabolic profile on 2 hydrothermal vents in SWIR were obtained based on cultivation-free metagenome sequencing. In particular, autotrophic sulfur oxidation supported by minerals was presumed, emphasizing the role of chimney minerals in supporting chemosynthesis. Presence of novel heterotrophic iron-oxidizing bacteria was also indicated, suggesting overlooked biogeochemical pathways directed by microorganisms that connected sulfide mineral dissolution and organic carbon degradation in hydrothermal vents. Our findings offer novel insights into microbial function and biotic interactions on minerals in ultraslow-spreading ridges.
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Affiliation(s)
- Ying-Wen Zhong
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, PR China
- Key Laboratory of Marine Ecosystem Dynamics, Ministry of Natural Resources & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, PR China
| | - Peng Zhou
- Key Laboratory of Marine Ecosystem Dynamics, Ministry of Natural Resources & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, PR China
| | - Hong Cheng
- Key Laboratory of Marine Ecosystem Dynamics, Ministry of Natural Resources & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, PR China
| | - Ya-Dong Zhou
- Key Laboratory of Marine Ecosystem Dynamics, Ministry of Natural Resources & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, PR China
| | - Jie Pan
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong, PR China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong, PR China
| | - Lin Xu
- Key Laboratory of Marine Ecosystem Dynamics, Ministry of Natural Resources & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, PR China
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, PR China
| | - Meng Li
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong, PR China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong, PR China
| | - Chun-Hui Tao
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, PR China
- Key Laboratory of Submarine Geosciences, Ministry of Natural Resources & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, PR China
| | - Yue-Hong Wu
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, PR China
- Key Laboratory of Marine Ecosystem Dynamics, Ministry of Natural Resources & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, PR China
| | - Xue-Wei Xu
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, PR China
- Key Laboratory of Marine Ecosystem Dynamics, Ministry of Natural Resources & Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, PR China
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11
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Sarkodie EK, Jiang L, Li K, Yang J, Guo Z, Shi J, Deng Y, Liu H, Jiang H, Liang Y, Yin H, Liu X. A review on the bioleaching of toxic metal(loid)s from contaminated soil: Insight into the mechanism of action and the role of influencing factors. Front Microbiol 2022; 13:1049277. [PMID: 36569074 PMCID: PMC9767989 DOI: 10.3389/fmicb.2022.1049277] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 11/18/2022] [Indexed: 12/12/2022] Open
Abstract
The anthropogenic activities in agriculture, industrialization, mining, and metallurgy combined with the natural weathering of rocks, have led to severe contamination of soils by toxic metal(loid)s. In an attempt to remediate these polluted sites, a plethora of conventional approaches such as Solidification/Stabilization (S/S), soil washing, electrokinetic remediation, and chemical oxidation/reduction have been used for the immobilization and removal of toxic metal(loid)s in the soil. However, these conventional methods are associated with certain limitations. These limitations include high operational costs, high energy demands, post-waste disposal difficulties, and secondary pollution. Bioleaching has proven to be a promising alternative to these conventional approaches in removing toxic metal(loid)s from contaminated soil as it is cost-effective, environmentally friendly, and esthetically pleasing. The bioleaching process is influenced by factors including pH, temperature, oxygen, and carbon dioxide supply, as well as nutrients in the medium. It is crucial to monitor these parameters before and throughout the reaction since a change in any, for instance, pH during the reaction, can alter the microbial activity and, therefore, the rate of metal leaching. However, research on these influencing factors and recent innovations has brought significant progress in bioleaching over the years. This critical review, therefore, presents the current approaches to bioleaching and the mechanisms involved in removing toxic metal(loid)s from contaminated soil. We further examined and discussed the fundamental principles of various influencing factors that necessitate optimization in the bioleaching process. Additionally, the future perspectives on adding omics for bioleaching as an emerging technology are discussed.
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Affiliation(s)
- Emmanuel Konadu Sarkodie
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Luhua Jiang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Kewei Li
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Jiejie Yang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Ziwen Guo
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Jiaxin Shi
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Yan Deng
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Hongwei Liu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Huidan Jiang
- Hunan Agricultural Biotechnology Research Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Yili Liang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Huaqun Yin
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Xueduan Liu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
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12
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Shen J, Luo Y, Tao Q, White PJ, Sun G, Li M, Luo J, He Y, Li B, Li Q, Xu Q, Cai Y, Li H, Wang C. The exacerbation of soil acidification correlates with structural and functional succession of the soil microbiome upon agricultural intensification. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 828:154524. [PMID: 35288138 DOI: 10.1016/j.scitotenv.2022.154524] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 02/28/2022] [Accepted: 03/08/2022] [Indexed: 06/14/2023]
Abstract
Agricultural intensification driven by land-use changes has caused continuous and cumulative soil acidification (SA) throughout the global agroecosystem. Microorganisms mediate acid-generating reactions; however, the microbial mechanisms responsible for exacerbating SA feedback remain largely unknown. To determine the microbial community composition and putative function associated with SA, we conducted a metagenomic analysis of soils across a chronosequence that has elapsed since the conversion of rice-wheat (RW) to rice-vegetable (RV) rotations. Compared to RW rotations, soil pH decreased by 0.50 and 1.56 units (p < 0.05) in response to 10-year and 20-year RV rotations, respectively. Additionally, acid saturation ratios were increased by 7.3% and 36.2% (p < 0.05), respectively. The loss of microbial beta-diversity was a key element that contributed to the exacerbation of SA in the RV. Notably, the 20-year RV-enriched microbial taxa were more hydrogen (H+)-, aluminium (Al3+)-, and nitrate nitrogen (NO3--N) -dependent and contained more genera exhibiting dehydrogenation functions than did RW-enriched taxa. "M00115, M00151, M00417, and M00004" and "M00531 and M00135" that are the "proton-pumping" and "proton-consuming" gene modules, respectively, were linked to the massive recruitment of acid-dependent biomarkers in 20-year RV soils, particularly Rhodanobacter, Gemmatirosa, Sphingomonas, and Streptomyces. Collectively, soils in long-term RV rotations were highly acidified and acid-sensitive, as the enrichment of microbial dehydrogenation genes allowing for soil buffering capacity is more vulnerable to H+ loading and consequently promotes the colonization of more acid-tolerant and acidogenic microbes, and ultimately provide new clues for researchers to elucidate the interaction between SA and the soil microbiome.
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Affiliation(s)
- Jie Shen
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China; Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | - Youlin Luo
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China
| | - Qi Tao
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China
| | - Philip J White
- The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Geng Sun
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | - Meng Li
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China
| | - Jipeng Luo
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yuting He
- Chengdu Popularization of Agricultural Technique Station, Chengdu 610041, China
| | - Bing Li
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China
| | - Qiquan Li
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China
| | - Qiang Xu
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China
| | - Yan Cai
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China
| | - Huanxiu Li
- Fruit and Vegetable Research Institute, Sichuan Agricultural University, Chengdu 611130, China
| | - Changquan Wang
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China.
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13
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Cortez D, Neira G, González C, Vergara E, Holmes DS. A Large-Scale Genome-Based Survey of Acidophilic Bacteria Suggests That Genome Streamlining Is an Adaption for Life at Low pH. Front Microbiol 2022; 13:803241. [PMID: 35387071 PMCID: PMC8978632 DOI: 10.3389/fmicb.2022.803241] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 02/07/2022] [Indexed: 01/04/2023] Open
Abstract
The genome streamlining theory suggests that reduction of microbial genome size optimizes energy utilization in stressful environments. Although this hypothesis has been explored in several cases of low-nutrient (oligotrophic) and high-temperature environments, little work has been carried out on microorganisms from low-pH environments, and what has been reported is inconclusive. In this study, we performed a large-scale comparative genomics investigation of more than 260 bacterial high-quality genome sequences of acidophiles, together with genomes of their closest phylogenetic relatives that live at circum-neutral pH. A statistically supported correlation is reported between reduction of genome size and decreasing pH that we demonstrate is due to gene loss and reduced gene sizes. This trend is independent from other genome size constraints such as temperature and G + C content. Genome streamlining in the evolution of acidophilic bacteria is thus supported by our results. The analyses of predicted Clusters of Orthologous Genes (COG) categories and subcellular location predictions indicate that acidophiles have a lower representation of genes encoding extracellular proteins, signal transduction mechanisms, and proteins with unknown function but are enriched in inner membrane proteins, chaperones, basic metabolism, and core cellular functions. Contrary to other reports for genome streamlining, there was no significant change in paralog frequencies across pH. However, a detailed analysis of COG categories revealed a higher proportion of genes in acidophiles in the following categories: "replication and repair," "amino acid transport," and "intracellular trafficking". This study brings increasing clarity regarding the genomic adaptations of acidophiles to life at low pH while putting elements, such as the reduction of average gene size, under the spotlight of streamlining theory.
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Affiliation(s)
- Diego Cortez
- Center for Bioinformatics and Genome Biology, Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - Gonzalo Neira
- Center for Bioinformatics and Genome Biology, Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - Carolina González
- Center for Bioinformatics and Genome Biology, Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - Eva Vergara
- Center for Bioinformatics and Genome Biology, Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - David S. Holmes
- Center for Bioinformatics and Genome Biology, Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastian, Santiago, Chile
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14
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Li M, Wen J. Recent progress in the application of omics technologies in the study of bio-mining microorganisms from extreme environments. Microb Cell Fact 2021; 20:178. [PMID: 34496835 PMCID: PMC8425152 DOI: 10.1186/s12934-021-01671-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 08/30/2021] [Indexed: 11/11/2022] Open
Abstract
Bio-mining microorganisms are a key factor affecting the metal recovery rate of bio-leaching, which inevitably produces an extremely acidic environment. As a powerful tool for exploring the adaptive mechanisms of microorganisms in extreme environments, omics technologies can greatly aid our understanding of bio-mining microorganisms and their communities on the gene, mRNA, and protein levels. These omics technologies have their own advantages in exploring microbial diversity, adaptive evolution, changes in metabolic characteristics, and resistance mechanisms of single strains or their communities to extreme environments. These technologies can also be used to discover potential new genes, enzymes, metabolites, metabolic pathways, and species. In addition, integrated multi-omics analysis can link information at different biomolecular levels, thereby obtaining more accurate and complete global adaptation mechanisms of bio-mining microorganisms. This review introduces the current status and future trends in the application of omics technologies in the study of bio-mining microorganisms and their communities in extreme environments.
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Affiliation(s)
- Min Li
- Key Laboratory of Systems Bioengineering, Tianjin University, Tianjin, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, China
- Frontier Science Center of Ministry of Education, Tianjin University, Tianjin, China
| | - Jianping Wen
- Key Laboratory of Systems Bioengineering, Tianjin University, Tianjin, China.
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, China.
- Frontier Science Center of Ministry of Education, Tianjin University, Tianjin, China.
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15
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Leucine-Responsive Regulatory Protein in Acetic Acid Bacteria Is Stable and Functions at a Wide Range of Intracellular pH Levels. J Bacteriol 2021; 203:e0016221. [PMID: 34228496 DOI: 10.1128/jb.00162-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acetic acid bacteria grow while producing acetic acid, resulting in acidification of the culture. Limited reports elucidate the effect of changes in intracellular pH on transcriptional factors. In the present study, the intracellular pH of Komagataeibacter europaeus was monitored with a pH-sensitive green fluorescent protein, showing that the intracellular pH decreased from 6.3 to 4.7 accompanied by acetic acid production during cell growth. The leucine-responsive regulatory protein of K. europaeus (KeLrp) was used as a model to examine pH-dependent effects, and its properties were compared with those of the Escherichia coli ortholog (EcLrp) at different pH levels. The DNA-binding activities of EcLrp and KeLrp with the target DNA (Ec-ilvI and Ke-ilvI) were examined by gel mobility shift assays under various pH conditions. EcLrp showed the highest affinity with the target at pH 8.0 (Kd [dissociation constant], 0.7 μM), decreasing to a minimum of 3.4 μM at pH 4.0. Conversely, KeLrp did not show significant differences in binding affinity between pH 4 and 7 (Kd, 1.0 to 1.5 μM), and the highest affinity was at pH 5.0 (Kd, 1.0 μM). Circular dichroism spectroscopy revealed that the α-helical content of KeLrp was the highest at pH 5.0 (49%) and was almost unchanged while being maintained at >45% over a range of pH levels examined, while that of EcLrp decreased from its maximum (49% at pH 7.0) to its minimum (36% at pH 4.0). These data indicate that KeLrp is stable and functions over a wide range of intracellular pH levels. IMPORTANCE Lrp is a highly conserved transcriptional regulator found in bacteria and archaea and regulates transcriptions of various genes. The intracellular pH of acetic acid bacteria (AAB) changes accompanied by acetic acid production during cell growth. The Lrp of AAB K. europaeus (KeLrp) was structurally stable over a wide range of pH and maintained DNA-binding activity even at low pH compared with Lrp from E. coli living in a neutral environment. An in vitro experiment showed DNA-binding activity of KeLrp to the target varied with changes in pH. In AAB, change of the intracellular pH during a cell growth would be an important trigger in controlling the activity of Lrp in vivo.
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16
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Feng S, Qiu Y, Huang Z, Yin Y, Zhang H, Zhu D, Tong Y, Yang H. The adaptation mechanisms of Acidithiobacillus caldus CCTCC M 2018054 to extreme acid stress: Bioleaching performance, physiology, and transcriptomics. ENVIRONMENTAL RESEARCH 2021; 199:111341. [PMID: 34015291 DOI: 10.1016/j.envres.2021.111341] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 05/09/2023]
Abstract
To understand the acid-resistant mechanism of bioleaching microorganism Acidithiobacillus caldus CCTCC M 2018054, its physiology and metabolic changes at the transcriptional level under extreme acid stress were systemically studied. Scanning electron microscopy (SEM), Fourier transform infrared reflection (FTIR) and X-ray diffraction (XRD) showed that with an increase in acidity, the absorption peak of sulfur oxidation-related functional groups such as S-O decreased significantly, and a dense sulfur passivation film appeared on the surface of the ore. Confocal laser scanning microscopy (CLSM) revealed that coverage scale of extracellular polymeric substance (EPS) and biofilm fluctuated accordingly along with the increasing acid stress (pH-stat 1.5, 1.2 0.9 and 0.6) during the bioleaching process. In response to acid stress, the increased levels of intracellular glutamic acid, alanine, cysteine, and proline contributed to the maintenance of intracellular pH homeostasis via decarboxylation and alkaline neutralization. Higher unsaturated fatty acid content was closely related to membrane fluidity. Up to 490 and 447 differentially expressed genes (DEGs) were identified at pH 1.5 vs pH 1.2 and pH 1.2 vs pH 0.9, respectively, and 177 common DEGs were associated with two-component system (TCS) regulation, transporter regulation, energy metabolism, and stress response. The upregulation of kdpB helped cells defend against proton invasion, whereas the downregulation of cysB and cbl implied stronger oxidation of sulfur compounds. The transcriptional level of sqr, sor, and soxA was significantly increased and consolidated the energy supply needed for resisting acid stress. Furthermore, eight of the identified DEGs (sor, cbl, ompA, atpF, nuoH, nuoC, sqr, grxB) were verified as being related to the acid stress response process. This study contributes toward expanding the application of these acidophiles in industrial bioleaching.
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Affiliation(s)
- Shoushuai Feng
- Key Laboratory of Carbohydrate Chemistry and Biotechnology (Jiangnan University) Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Yongkang Qiu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology (Jiangnan University) Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Zhuangzhuang Huang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology (Jiangnan University) Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Yijun Yin
- Key Laboratory of Carbohydrate Chemistry and Biotechnology (Jiangnan University) Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Hailing Zhang
- Department of Biological Engineering, College of Life Science, Yantai University, Shandong, 408100, China
| | - Deqiang Zhu
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan, 250353, China
| | - Yanjun Tong
- Key Laboratory of Carbohydrate Chemistry and Biotechnology (Jiangnan University) Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China.
| | - Hailin Yang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology (Jiangnan University) Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, China.
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17
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Barahona S, Castro-Severyn J, Dorador C, Saavedra C, Remonsellez F. Determinants of Copper Resistance in Acidithiobacillus Ferrivorans ACH Isolated from the Chilean Altiplano. Genes (Basel) 2020; 11:genes11080844. [PMID: 32722087 PMCID: PMC7463520 DOI: 10.3390/genes11080844] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/22/2020] [Accepted: 07/22/2020] [Indexed: 11/16/2022] Open
Abstract
The use of microorganisms in mining processes is a technology widely employed around the world. Leaching bacteria are characterized by having resistance mechanisms for several metals found in their acidic environments, some of which have been partially described in the Acidithiobacillus genus (mainly on ferrooxidans species). However, the response to copper has not been studied in the psychrotolerant Acidithiobacillus ferrivorans strains. Therefore, we propose to elucidate the response mechanisms of A. ferrivorans ACH to high copper concentrations (0-800 mM), describing its genetic repertoire and transcriptional regulation. Our results show that A. ferrivorans ACH can grow in up to 400 mM of copper. Moreover, we found the presence of several copper-related makers, belonging to cop and cus systems, as well as rusticyanins and periplasmatic acop protein in the genome. Interestingly, the ACH strain is the only one in which we find three copies of copB and copZ genes. Moreover, transcriptional expression showed an up-regulation response (acop, copZ, cusA, rusA, and rusB) to high copper concentrations. Finally, our results support the important role of these genes in A. ferrivorans copper stress resistance, promoting the use of the ACH strain in industrial leaching under low temperatures, which could decrease the activation times of oxidation processes and the energy costs.
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Affiliation(s)
- Sergio Barahona
- Laboratorio de Microbiología Aplicada y Extremófilos, Departamento de Ingeniería Química, Universidad Católica del Norte, Antofagasta 1240000, Chile;
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Departamento de Biotecnología, Facultad de Ciencias del Mar y Recurso Biológicos, Universidad de Antofagasta, Antofagasta 1240000, Chile;
- Programa de Doctorado en Ingeniería de Procesos de Minerales, Facultad de Ingeniería, Universidad de Antofagasta, Antofagasta 1240000, Chile
- Correspondence: (S.B.); (F.R.)
| | - Juan Castro-Severyn
- Laboratorio de Microbiología Aplicada y Extremófilos, Departamento de Ingeniería Química, Universidad Católica del Norte, Antofagasta 1240000, Chile;
| | - Cristina Dorador
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Departamento de Biotecnología, Facultad de Ciencias del Mar y Recurso Biológicos, Universidad de Antofagasta, Antofagasta 1240000, Chile;
- Centro de Biotecnología y Bioingeniería (CeBiB), Universidad de Antofagasta, Antofagasta 1240000, Chile
| | - Claudia Saavedra
- Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago 8320000, Chile;
| | - Francisco Remonsellez
- Laboratorio de Microbiología Aplicada y Extremófilos, Departamento de Ingeniería Química, Universidad Católica del Norte, Antofagasta 1240000, Chile;
- Centro de Investigación Tecnológica del Agua en el Desierto (CEITSAZA), Universidad Católica del Norte, Antofagasta 1240000, Chile
- Correspondence: (S.B.); (F.R.)
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18
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Vargas-Straube MJ, Beard S, Norambuena R, Paradela A, Vera M, Jerez CA. High copper concentration reduces biofilm formation in Acidithiobacillus ferrooxidans by decreasing production of extracellular polymeric substances and its adherence to elemental sulfur. J Proteomics 2020; 225:103874. [PMID: 32569817 DOI: 10.1016/j.jprot.2020.103874] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/04/2020] [Accepted: 06/06/2020] [Indexed: 12/14/2022]
Abstract
Acidithiobacillus ferrooxidans is an acidophilic bacterium able to grow in environments with high concentrations of metals. It is a chemolithoautotroph able to form biofilms on the surface of solid minerals to obtain its energy. The response of both planktonic and sessile cells of A. ferrooxidans ATCC 23270 grown in elemental sulfur and adapted to high copper concentration was analyzed by quantitative proteomics. It was found that 137 proteins varied their abundance when comparing both lifestyles. Copper effllux proteins, some subunits of the ATP synthase complex, porins, and proteins involved in cell wall modification increased their abundance in copper-adapted sessile lifestyle cells. On the other hand, planktonic copper-adapted cells showed increased levels of proteins such as: cupreredoxins involved in copper cell sequestration, some proteins related to sulfur metabolism, those involved in biosynthesis and transport of lipopolysaccharides, and in assembly of type IV pili. During copper adaptation a decreased formation of biofilms was measured as determined by epifluorescence microscopy. This was apparently due not only to a diminished number of sessile cells but also to their exopolysaccharides production. This is the first study showing that copper, a prevalent metal in biomining environments causes dispersion of A. ferrooxidans biofilms. SIGNIFICANCE: Copper is a metal frequently found in high concentrations at mining environments inhabitated by acidophilic microorganisms. Copper resistance determinants of A. ferrooxidans have been previously studied in planktonic cells. Although biofilms are recurrent in these types of environments, the effect of copper on their formation has not been studied so far. The results obtained indicate that high concentrations of copper reduce the capacity of A. ferrooxidans ATCC 23270 to form biofilms on sulfur. These findings may be relevant to consider for a bacterium widely used in copper bioleaching processes.
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Affiliation(s)
- M J Vargas-Straube
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - S Beard
- Fundación Ciencia y Vida, Santiago, Chile
| | - R Norambuena
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - A Paradela
- Proteomics Laboratory, National Biotechnology Center, CSIC, Madrid, Spain
| | - M Vera
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.; Department of Hydraulic and Environmental Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - C A Jerez
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile..
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19
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Evolution of Predicted Acid Resistance Mechanisms in the Extremely Acidophilic Leptospirillum Genus. Genes (Basel) 2020; 11:genes11040389. [PMID: 32260256 PMCID: PMC7231039 DOI: 10.3390/genes11040389] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/02/2020] [Accepted: 03/04/2020] [Indexed: 02/01/2023] Open
Abstract
Organisms that thrive in extremely acidic environments (≤pH 3.5) are of widespread importance in industrial applications, environmental issues, and evolutionary studies. Leptospirillum spp. constitute the only extremely acidophilic microbes in the phylogenetically deep-rooted bacterial phylum Nitrospirae. Leptospirilli are Gram-negative, obligatory chemolithoautotrophic, aerobic, ferrous iron oxidizers. This paper predicts genes that Leptospirilli use to survive at low pH and infers their evolutionary trajectory. Phylogenetic and other bioinformatic approaches suggest that these genes can be classified into (i) "first line of defense", involved in the prevention of the entry of protons into the cell, and (ii) neutralization or expulsion of protons that enter the cell. The first line of defense includes potassium transporters, predicted to form an inside positive membrane potential, spermidines, hopanoids, and Slps (starvation-inducible outer membrane proteins). The "second line of defense" includes proton pumps and enzymes that consume protons. Maximum parsimony, clustering methods, and gene alignments are used to infer the evolutionary trajectory that potentially enabled the ancestral Leptospirillum to transition from a postulated circum-neutral pH environment to an extremely acidic one. The hypothesized trajectory includes gene gains/loss events driven extensively by horizontal gene transfer, gene duplications, gene mutations, and genomic rearrangements.
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20
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González D, Álamos P, Rivero M, Orellana O, Norambuena J, Chávez R, Levicán G. Deciphering the Role of Multiple Thioredoxin Fold Proteins of Leptospirillum sp. in Oxidative Stress Tolerance. Int J Mol Sci 2020; 21:E1880. [PMID: 32164170 PMCID: PMC7084401 DOI: 10.3390/ijms21051880] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 12/22/2022] Open
Abstract
Thioredoxin fold proteins (TFPs) form a family of diverse proteins involved in thiol/disulfide exchange in cells from all domains of life. Leptospirillum spp. are bioleaching bacteria naturally exposed to extreme conditions like acidic pH and high concentrations of metals that can contribute to the generation of reactive oxygen species (ROS) and consequently the induction of thiol oxidative damage. Bioinformatic studies have predicted 13 genes that encode for TFP proteins in Leptospirillum spp. We analyzed the participation of individual tfp genes from Leptospirillum sp. CF-1 in the response to oxidative conditions. Genomic context analysis predicted the involvement of these genes in the general thiol-reducing system, cofactor biosynthesis, carbon fixation, cytochrome c biogenesis, signal transduction, and pilus and fimbria assembly. All tfp genes identified were transcriptionally active, although they responded differentially to ferric sulfate and diamide stress. Some of these genes confer oxidative protection to a thioredoxin-deficient Escherichia coli strain by restoring the wild-type phenotype under oxidative stress conditions. These findings contribute to our understanding of the diversity and complexity of thiol/disulfide systems, and of adaptations that emerge in acidophilic microorganisms that allow them to thrive in highly oxidative environments. These findings also give new insights into the physiology of these microorganisms during industrial bioleaching operations.
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Affiliation(s)
- Daniela González
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Avenida Libertador Bernardo O’Higgins 3363, Estación Central Santiago 917022, Chile; (D.G.); (P.Á.); (M.R.); (J.N.); (R.C.)
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile;
| | - Pamela Álamos
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Avenida Libertador Bernardo O’Higgins 3363, Estación Central Santiago 917022, Chile; (D.G.); (P.Á.); (M.R.); (J.N.); (R.C.)
| | - Matías Rivero
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Avenida Libertador Bernardo O’Higgins 3363, Estación Central Santiago 917022, Chile; (D.G.); (P.Á.); (M.R.); (J.N.); (R.C.)
| | - Omar Orellana
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile;
| | - Javiera Norambuena
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Avenida Libertador Bernardo O’Higgins 3363, Estación Central Santiago 917022, Chile; (D.G.); (P.Á.); (M.R.); (J.N.); (R.C.)
| | - Renato Chávez
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Avenida Libertador Bernardo O’Higgins 3363, Estación Central Santiago 917022, Chile; (D.G.); (P.Á.); (M.R.); (J.N.); (R.C.)
| | - Gloria Levicán
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Avenida Libertador Bernardo O’Higgins 3363, Estación Central Santiago 917022, Chile; (D.G.); (P.Á.); (M.R.); (J.N.); (R.C.)
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21
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Blake RC, White RA. In situ absorbance measurements: a new means to study respiratory electron transfer in chemolithotrophic microorganisms. Adv Microb Physiol 2020; 76:81-127. [PMID: 32408948 DOI: 10.1016/bs.ampbs.2020.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Absorbance measurements on intact chemolithotrophic microorganisms that respire aerobically on soluble iron are described that used a novel integrating cavity absorption meter to eliminate the effects of light scattering on the experimental results. Steady state kinetic measurements on ferric iron production by intact cells revealed that the Michaelis Menten equation described the initial rates of product formation for at least 8 different chemolithotrophic microorganisms in 6 phyla distributed equally among the archaea and the Gram negative and Gram positive eubacteria. Cell-monitored turnover measurements during aerobic respiration on soluble iron by the same 12 intact microorganisms revealed six different patterns of iron-dependent absorbance changes, suggesting that there may be at least six different sets of prosthetic groups and biomolecules that can accomplish aerobic respiration on soluble iron. Detailed kinetic studies revealed that the 3-component iron respiratory chain of Acidithiobacillus ferrooxidans functioned as an ensemble with a single macroscopic rate constant when the iron-reduced proteins were oxidized in the presence of excess molecular oxygen. The principal member of this 3-component system was a cupredoxin called rusticyanin that was present in the periplasm of At. ferrooxidans at an approximate concentration of 350 mg/mL, an observation that provides new insights into the crowded environments in the periplasms of Gram negative eubacteria that conduct electrons across their periplasm. The ability to conduct direct spectrophotometric measurements under noninvasive physiological conditions represents a new and powerful approach to examine the rates and extents of biological events in situ without disrupting the complexity of the live cellular environment.
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Affiliation(s)
- Robert C Blake
- College of Pharmacy, Xavier University of Louisiana, New Orleans, United States
| | - Richard A White
- Department of Plant Pathology, Washington State University, Pullman, WA, United States; RAW Molecular Systems (RMS) LLC, Spokane, WA, United States; Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW, Australia
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22
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Giovanella P, Vieira GAL, Ramos Otero IV, Pais Pellizzer E, de Jesus Fontes B, Sette LD. Metal and organic pollutants bioremediation by extremophile microorganisms. JOURNAL OF HAZARDOUS MATERIALS 2020; 382:121024. [PMID: 31541933 DOI: 10.1016/j.jhazmat.2019.121024] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 07/17/2019] [Accepted: 08/14/2019] [Indexed: 06/10/2023]
Abstract
Extremophiles comprise microorganisms that are able to grow and thrive in extreme environments, including in an acidic or alkaline pH, high or low temperatures, high concentrations of pollutants, and salts, among others. These organisms are promising for environmental biotechnology due to their unique physiological and enzymatic characteristics, which allow them to survive in harsh environments. Due to the stability and persistence of these microorganisms under adverse environmental conditions, they can be used for the bioremediation of environments contaminated with extremely recalcitrant pollutants. Here, we provide an overview of extremophiles and the role of "omics" in the field of bioremediation of environmental pollutants, including hydrocarbons, textile dyes and metals.
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Affiliation(s)
- Patricia Giovanella
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho, Rio Claro, SP, Brazil.
| | - Gabriela A L Vieira
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho, Rio Claro, SP, Brazil
| | - Igor V Ramos Otero
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho, Rio Claro, SP, Brazil
| | - Elisa Pais Pellizzer
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho, Rio Claro, SP, Brazil
| | - Bruno de Jesus Fontes
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho, Rio Claro, SP, Brazil
| | - Lara D Sette
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho, Rio Claro, SP, Brazil.
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23
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Insights into the Periplasmic Proteins of Acinetobacter baumannii AB5075 and the Impact of Imipenem Exposure: A Proteomic Approach. Int J Mol Sci 2019; 20:ijms20143451. [PMID: 31337077 PMCID: PMC6679007 DOI: 10.3390/ijms20143451] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 07/09/2019] [Accepted: 07/10/2019] [Indexed: 02/08/2023] Open
Abstract
Carbapenem-resistant Acinetobacter baumannii strains cause life-threatening infections due to the lack of therapeutic options. Although the main mechanisms underlying antibiotic-resistance have been extensively studied, the general response to maintain bacterial viability under antibiotic exposure deserves to be fully investigated. Since the periplasmic space contains several proteins with crucial cellular functions, besides carbapenemases, we decided to study the periplasmic proteome of the multidrug-resistant (MDR) A. baumannii AB5075 strain, grown in the absence and presence of imipenem (IMP). Through the proteomic approach, 65 unique periplasmic proteins common in both growth conditions were identified: eight proteins involved in protein fate, response to oxidative stress, energy metabolism, antibiotic-resistance, were differentially expressed. Among them, ABUW_1746 and ABUW_2363 gene products presented the tetratricopeptide repeat motif, mediating protein-protein interactions. The expression switch of these proteins might determine specific protein interactions to better adapt to changing environmental conditions. ABUW_2868, encoding a heat shock protein likely involved in protection against oxidative stress, was upregulated in IMP-exposed bacteria. Accordingly, the addition of periplasmic proteins from A. baumannii cultured with IMP increased bacterial viability in an antioxidant activity assay. Overall, this study provides the first insights about the composition of the periplasmic proteins of a MDR A. baumannii strain, its biological response to IMP and suggests possible new targets to develop alternative antibiotic drugs.
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24
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Zhan Y, Yang M, Zhang S, Zhao D, Duan J, Wang W, Yan L. Iron and sulfur oxidation pathways of Acidithiobacillus ferrooxidans. World J Microbiol Biotechnol 2019; 35:60. [PMID: 30919119 DOI: 10.1007/s11274-019-2632-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 03/08/2019] [Indexed: 12/13/2022]
Abstract
Acidithiobacillus ferrooxidans is a gram-negative, autotrophic and rod-shaped bacterium. It can gain energy through the oxidation of Fe(II) and reduced inorganic sulfur compounds for bacterial growth when oxygen is sufficient. It can be used for bio-leaching and bio-oxidation and contributes to the geobiochemical circulation of metal elements and nutrients in acid mine drainage environments. The iron and sulfur oxidation pathways of A. ferrooxidans play key roles in bacterial growth and survival under extreme circumstances. Here, the electrons transported through the thermodynamically favourable pathway for the reduction to H2O (downhill pathway) and against the redox potential gradient reduce to NAD(P)(H) (uphill pathway) during the oxidation of Fe(II) were reviewed, mainly including the electron transport carrier, relevant operon and regulation of its expression. Similar to the electron transfer pathway, the sulfur oxidation pathway of A. ferrooxidans, related genes and operons, sulfur oxidation mechanism and sulfur oxidase system are systematically discussed.
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Affiliation(s)
- Yue Zhan
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China
| | - Mengran Yang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China
| | - Shuang Zhang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China
| | - Dan Zhao
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China
| | - Jiangong Duan
- School of Pharmacy, Lanzhou University, Donggang West Road No. 199, Lanzhou, 730020, Gansu Province, People's Republic of China
| | - Weidong Wang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China
| | - Lei Yan
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China. .,College of Food Science, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China.
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25
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Electrochemical Behavior of Ocean Polymetallic Nodules and Low-Grade Nickel Sulfide Ore in Acidithiobacillus Ferrooxidans-Coupled Bio-Leaching. MINERALS 2019. [DOI: 10.3390/min9020070] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Efficient extraction of Ni, Co, Cu, and Mn from low-grade and refractory ores is a common technical challenge. The present study proposes an Acidithiobacillus ferrooxidans-coupled leaching of Ni, Cu, Co, and Mn from oceanic polymetallic nodules and low-grade nickel sulfide ore, and focuses on the electrochemical behavior of the ores in simulated bio-leaching solutions. In the dissolution of polymetallic nodules, A. ferrooxidans facilitates the diffusion of H+ and accelerates electron transfer, producing a decrease in charge transfer resistance and promoting the Mn(IV)-preceding reaction. The use of A. ferrooxidans is beneficial for lower impedance of sulfur-nickel ore, faster diffusion rate of product layer, and better transformation of the Fe3+/Fe2+ couple and S0/S2− couple. A. ferrooxidans increases the potential difference between the nodule cathode and sulfide anode, and increases electron liberation from the sulfide ore. This motivates a significant increase in the average extraction rates of Ni, Co, Cu, and Mn in the bacterial solution. The bio-leaching efficiencies of Ni, Co, Cu, and Mn were as high as 95.4%, 97.8%, 92.2% and 97.3%, respectively, representing improvements of 17.1%, 11.5%, 14.3% and 12.9% relative to that of the germ- and Fe(III)-free acidic 9 K basic system.
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26
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Oetiker N, Norambuena R, Martínez-Bussenius C, Navarro CA, Amaya F, Álvarez SA, Paradela A, Jerez CA. Possible Role of Envelope Components in the Extreme Copper Resistance of the Biomining Acidithiobacillus ferrooxidans. Genes (Basel) 2018; 9:genes9070347. [PMID: 29996532 PMCID: PMC6070983 DOI: 10.3390/genes9070347] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 06/30/2018] [Accepted: 07/03/2018] [Indexed: 01/01/2023] Open
Abstract
Acidithiobacillus ferrooxidans resists extremely high concentrations of copper. Strain ATCC 53993 is much more resistant to the metal compared with strain ATCC 23270, possibly due to the presence of a genomic island in the former one. The global response of strain ATCC 53993 to copper was analyzed using iTRAQ (isobaric tag for relative and absolute quantitation) quantitative proteomics. Sixty-seven proteins changed their levels of synthesis in the presence of the metal. On addition of CusCBA efflux system proteins, increased levels of other envelope proteins, such as a putative periplasmic glucan biosynthesis protein (MdoG) involved in the osmoregulated synthesis of glucans and a putative antigen O polymerase (Wzy), were seen in the presence of copper. The expression of A. ferrooxidansmdoG or wzy genes in a copper sensitive Escherichia coli conferred it a higher metal resistance, suggesting the possible role of these components in copper resistance of A. ferrooxidans. Transcriptional levels of genes wzy, rfaE and wzz also increased in strain ATCC 23270 grown in the presence of copper, but not in strain ATCC 53993. Additionally, in the absence of this metal, lipopolysaccharide (LPS) amounts were 3-fold higher in A. ferrooxidans ATCC 53993 compared with strain 23270. Nevertheless, both strains grown in the presence of copper contained similar LPS quantities, suggesting that strain 23270 synthesizes higher amounts of LPS to resist the metal. On the other hand, several porins diminished their levels in the presence of copper. The data presented here point to an essential role for several envelope components in the extreme copper resistance by this industrially important acidophilic bacterium.
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Affiliation(s)
- Nia Oetiker
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, Santiago 7800003, Chile.
| | - Rodrigo Norambuena
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, Santiago 7800003, Chile.
| | - Cristóbal Martínez-Bussenius
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, Santiago 7800003, Chile.
| | - Claudio A Navarro
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, Santiago 7800003, Chile.
| | - Fernando Amaya
- Department of Biochemistry and Molecular Biology, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 7800003, Chile.
| | - Sergio A Álvarez
- Department of Biochemistry and Molecular Biology, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago 7800003, Chile.
| | - Alberto Paradela
- Proteomics Laboratory, National Biotechnology Center, CSIC, 28049 Madrid, Spain.
| | - Carlos A Jerez
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, Santiago 7800003, Chile.
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27
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Zhang S, Yan L, Xing W, Chen P, Zhang Y, Wang W. Acidithiobacillus ferrooxidans and its potential application. Extremophiles 2018; 22:563-579. [PMID: 29696439 DOI: 10.1007/s00792-018-1024-9] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 04/02/2018] [Indexed: 11/30/2022]
Abstract
The widely distributed Acidithiobacillus ferrooxidans (A. ferrooxidans) lives in extremely acidic conditions by fixing CO2 and nitrogen, and by obtaining energy from Fe2+ oxidation with either downhill or uphill electron transfer pathway and from reduced sulfur oxidation. A. ferrooxidans exists as different genomovars and its genome size is 2.89-4.18 Mb. The chemotactic movement of A. ferrooxidans is regulated by quorum sensing. A. ferrooxidans shows weak magnetotaxis due to formation of 15-70 nm magnetite magnetosomes with surface functional groups. The room- and low-temperature magnetic features of A. ferrooxidans are different from other magnetotactic bacteria. A. ferrooxidans has potential for removing sulfur from solids and gases, metals recycling from metal-bearing ores, electric wastes and sludge, biochemical production synthesizing, and metal workpiece machining.
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Affiliation(s)
- Shuang Zhang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University (HBAU), 5 Xinfeng Road, Daqing High-Tech Industrial Development Zone, Daqing, 163319, Heilongjiang, People's Republic of China
| | - Lei Yan
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University (HBAU), 5 Xinfeng Road, Daqing High-Tech Industrial Development Zone, Daqing, 163319, Heilongjiang, People's Republic of China.
| | - Weijia Xing
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University (HBAU), 5 Xinfeng Road, Daqing High-Tech Industrial Development Zone, Daqing, 163319, Heilongjiang, People's Republic of China
| | - Peng Chen
- School of Pharmacy, Lanzhou University, Donggang West Road No. 199, Lanzhou, 730020, People's Republic of China
| | - Yu Zhang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University (HBAU), 5 Xinfeng Road, Daqing High-Tech Industrial Development Zone, Daqing, 163319, Heilongjiang, People's Republic of China
| | - Weidong Wang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University (HBAU), 5 Xinfeng Road, Daqing High-Tech Industrial Development Zone, Daqing, 163319, Heilongjiang, People's Republic of China
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28
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Guiral M, Neitzel C, Salvador Castell M, Martinez N, Giudici-Orticoni MT, Peters J. The effect of pH on the dynamics of natural membranes. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2018; 41:22. [PMID: 29464436 DOI: 10.1140/epje/i2018-11630-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 01/25/2018] [Indexed: 06/08/2023]
Abstract
Pure phospholipids and membrane fragments from bacterial cells living under various conditions were studied against the influence of the surrounding acidity on the internal dynamics. For that we compared mean square displacements extracted from elastic incoherent neutron scattering data, measured both at low and at neutral pH, of the phospholipids 1,2-dimyristoyl-sn-glycero-3-phosphocholine and of samples from neutralophilic and acidophilic micro-organisms (some being hyperthermophilic and others mesophilic). The lipids showed a slight shift in the phase transition temperature of about 4 degrees under pH variation and became slightly more mobile at lower pH. The membrane fragments not used to extreme acidic conditions were significantly more sensitive to variations in the pH values, whereas the acidophilic and -tolerant samples were much less influenced by this parameter. They presented the higher softness at low pH, which was closer to their native condition. Such findings might be a hint for adaptation mechanisms to different acidity conditions.
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Affiliation(s)
- M Guiral
- Aix Marseille Univ, CNRS, BIP, Marseille, France
| | - C Neitzel
- Univ. Grenoble Alpes, CNRS, LiPhy, F-38000, Grenoble, France
- Institut Laue Langevin, Cedex 9, F-38042, Grenoble, France
| | - M Salvador Castell
- Univ. Grenoble Alpes, CNRS, LiPhy, F-38000, Grenoble, France
- Institut Laue Langevin, Cedex 9, F-38042, Grenoble, France
| | - N Martinez
- Univ. Grenoble Alpes, CNRS, LiPhy, F-38000, Grenoble, France
- Institut Laue Langevin, Cedex 9, F-38042, Grenoble, France
| | | | - J Peters
- Univ. Grenoble Alpes, CNRS, LiPhy, F-38000, Grenoble, France.
- Institut Laue Langevin, Cedex 9, F-38042, Grenoble, France.
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29
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Martínez-Bussenius C, Navarro CA, Jerez CA. Microbial copper resistance: importance in biohydrometallurgy. Microb Biotechnol 2016; 10:279-295. [PMID: 27790868 PMCID: PMC5328820 DOI: 10.1111/1751-7915.12450] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 09/30/2016] [Accepted: 10/03/2016] [Indexed: 11/29/2022] Open
Abstract
Industrial biomining has been extensively used for many years to recover valuable metals such as copper, gold, uranium and others. Furthermore, microorganisms involved in these processes can also be used to bioremediate places contaminated with acid and metals. These uses are possible due to the great metal resistance that these extreme acidophilic microorganisms possess. In this review, the most recent findings related to copper resistance mechanisms of bacteria and archaea related to biohydrometallurgy are described. The recent search for novel metal resistance determinants is not only of scientific interest but also of industrial importance, as reflected by the genomic sequencing of microorganisms present in mining operations and the search of those bacteria with extreme metal resistance to improve the extraction processes used by the biomining companies.
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Affiliation(s)
- Cristóbal Martínez-Bussenius
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Claudio A Navarro
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Carlos A Jerez
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
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30
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Merino MP, Andrews BA, Parada P, Asenjo JA. Characterization of Ferroplasma acidiphilum growing in pure and mixed culture with Leptospirillum ferriphilum. Biotechnol Prog 2016; 32:1390-1396. [PMID: 27535541 DOI: 10.1002/btpr.2340] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 05/27/2016] [Indexed: 11/07/2022]
Abstract
Biomining is defined as biotechnology for metal recovery from minerals, and is promoted by the concerted effort of a consortium of acidophile prokaryotes, comprised of members of the Bacteria and Archaea domains. Ferroplasma acidiphilum and Leptospirillum ferriphilum are the dominant species in extremely acid environments and have great use in bioleaching applications; however, the role of each species in this consortia is still a subject of research. The hypothesis of this work is that F. acidiphilum uses the organic matter secreted by L. ferriphilum for growth, maintaining low levels of organic compounds in the culture medium, preventing their toxic effects on L. ferriphilum. To test this hypothesis, a characterization of Ferroplasma acidiphilum strain BRL-115 was made with the objective of determining its optimal growth conditions. Subsequently, under the optimal conditions, L. ferriphilum and F. acidiphilum were tested growing in each other's supernatant, in order to define if there was exchange of metabolites between the species. With these results, a mixed culture in batch cyclic operation was performed to obtain main specific growth rates, which were used to evaluate a mixed metabolic model previously developed by our group. It was observed that F. acidiphilum, strain BRL-115 is a chemomixotrophic organism, and its growth is maximized with yeast extract at a concentration of 0.04% wt/vol. From the experiments of L. ferriphilum growing on F. acidiphilum supernatant and vice versa, it was observed that in both cases cell growth is favorably affected by the presence of the filtered medium of the other microorganism, proving a synergistic interaction between these species. Specific growth rates were obtained in cyclic batch operation of the mixed culture and were used as input data for a Flux Balance Analysis of the mixed metabolic model, obtaining a reasonable behavior of the metabolic fluxes and the system as a whole, therefore consolidating the model previously developed. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1390-1396, 2016.
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Affiliation(s)
- M P Merino
- Centre for Biotechnology and Bioengineering, CeBiB, Dept. of Chemical Engineering and Biotechnology, University of Chile, Beauchef 851, Santiago, Chile
| | - B A Andrews
- Centre for Biotechnology and Bioengineering, CeBiB, Dept. of Chemical Engineering and Biotechnology, University of Chile, Beauchef 851, Santiago, Chile
| | - P Parada
- Biosigma S.A, Carretera Gral. San Martín 16500, Loteo Industrial Los Libertadores, Lote 106, Colina, Chile
| | - J A Asenjo
- Centre for Biotechnology and Bioengineering, CeBiB, Dept. of Chemical Engineering and Biotechnology, University of Chile, Beauchef 851, Santiago, Chile
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Latorre M, Ehrenfeld N, Cortés MP, Travisany D, Budinich M, Aravena A, González M, Bobadilla-Fazzini RA, Parada P, Maass A. Global transcriptional responses of Acidithiobacillus ferrooxidans Wenelen under different sulfide minerals. BIORESOURCE TECHNOLOGY 2016; 200:29-34. [PMID: 26476161 DOI: 10.1016/j.biortech.2015.09.110] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 09/28/2015] [Accepted: 09/29/2015] [Indexed: 06/05/2023]
Abstract
In order to provide new information about the adaptation of Acidithiobacillus ferrooxidans during the bioleaching process, the current analysis presents the first report of the global transcriptional response of the native copper mine strain Wenelen (DSM 16786) oxidized under different sulfide minerals. Microarrays were used to measure the response of At. ferrooxidans Wenelen to shifts from iron supplemented liquid cultures (reference state) to the addition of solid substrates enriched in pyrite or chalcopyrite. Genes encoding for energy metabolism showed a similar transcriptional profile for the two sulfide minerals. Interestingly, four operons related to sulfur metabolism were over-expressed during growth on a reduced sulfur source. Genes associated with metal tolerance (RND and ATPases type P) were up-regulated in the presence of pyrite or chalcopyrite. These results suggest that At. ferrooxidans Wenelen presents an efficient transcriptional system developed to respond to environmental conditions, namely the ability to withstand high copper concentrations.
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Affiliation(s)
- Mauricio Latorre
- Mathomics, Center for Mathematical Modeling, Universidad de Chile, Beauchef 851, 7th Floor, Santiago, Chile; Center for Genome Regulation (Fondap 15090007), Universidad de Chile, Blanco Encalada 2085, Santiago, Chile; Laboratorio de Bioinformática y Expresión Génica, INTA, Universidad de Chile, El Líbano 5524, Macul, Santiago, Chile
| | - Nicole Ehrenfeld
- BioSigma S.A., Loteo Los Libertadores, Lote 106, Colina, Chile; Austral Biotech S.A., Francisco Noguera 41, Santiago, Chile
| | - María Paz Cortés
- Mathomics, Center for Mathematical Modeling, Universidad de Chile, Beauchef 851, 7th Floor, Santiago, Chile; Center for Genome Regulation (Fondap 15090007), Universidad de Chile, Blanco Encalada 2085, Santiago, Chile
| | - Dante Travisany
- Mathomics, Center for Mathematical Modeling, Universidad de Chile, Beauchef 851, 7th Floor, Santiago, Chile; Center for Genome Regulation (Fondap 15090007), Universidad de Chile, Blanco Encalada 2085, Santiago, Chile
| | - Marko Budinich
- Mathomics, Center for Mathematical Modeling, Universidad de Chile, Beauchef 851, 7th Floor, Santiago, Chile; Center for Genome Regulation (Fondap 15090007), Universidad de Chile, Blanco Encalada 2085, Santiago, Chile
| | - Andrés Aravena
- Department of Molecular Biology and Genetics, Istanbul University, Istanbul, Turkey
| | - Mauricio González
- Center for Genome Regulation (Fondap 15090007), Universidad de Chile, Blanco Encalada 2085, Santiago, Chile; Laboratorio de Bioinformática y Expresión Génica, INTA, Universidad de Chile, El Líbano 5524, Macul, Santiago, Chile
| | | | - Pilar Parada
- BioSigma S.A., Loteo Los Libertadores, Lote 106, Colina, Chile
| | - Alejandro Maass
- Mathomics, Center for Mathematical Modeling, Universidad de Chile, Beauchef 851, 7th Floor, Santiago, Chile; Center for Genome Regulation (Fondap 15090007), Universidad de Chile, Blanco Encalada 2085, Santiago, Chile; BioSigma S.A., Loteo Los Libertadores, Lote 106, Colina, Chile; Department of Mathematical Engineering, Universidad de Chile, Beauchef 851, 5th Floor, Santiago, Chile.
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Evidence of cell surface iron speciation of acidophilic iron-oxidizing microorganisms in indirect bioleaching process. Biometals 2015; 29:25-37. [PMID: 26645388 DOI: 10.1007/s10534-015-9893-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Accepted: 11/04/2015] [Indexed: 10/22/2022]
Abstract
While indirect model has been widely accepted in bioleaching, but the evidence of cell surface iron speciation has not been reported. In the present work the iron speciation on the cell surfaces of four typically acidophilic iron-oxidizing microorganism (mesophilic Acidithiobacillus ferrooxidans ATCC 23270, moderately thermophilic Leptospirillum ferriphilum YSK and Sulfobacillus thermosulfidooxidans St, and extremely thermophilic Acidianus manzaensis YN25) grown on different energy substrates (chalcopyrite, pyrite, ferrous sulfate and elemental sulfur (S(0))) were studied in situ firstly by using synchrotron-based micro- X-ray fluorescence analysis and X-ray absorption near-edge structure spectroscopy. Results showed that the cells grown on iron-containing substrates had apparently higher surface iron content than the cells grown on S(0). Both ferrous iron and ferric iron were detected on the cell surface of all tested AIOMs, and the Fe(II)/Fe(III) ratios of the same microorganism were affected by different energy substrates. The iron distribution and bonding state of single cell of A. manzaensis were then studied in situ by scanning transmission soft X-ray microscopy based on dual-energy contrast analysis and stack analysis. Results showed that the iron species distributed evenly on the cell surface and bonded with amino, carboxyl and hydroxyl groups.
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Cytoplasmic CopZ-Like Protein and Periplasmic Rusticyanin and AcoP Proteins as Possible Copper Resistance Determinants in Acidithiobacillus ferrooxidans ATCC 23270. Appl Environ Microbiol 2015; 82:1015-1022. [PMID: 26637599 DOI: 10.1128/aem.02810-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 11/20/2015] [Indexed: 11/20/2022] Open
Abstract
Acidophilic organisms, such as Acidithiobacillus ferrooxidans, possess high-level resistance to copper and other metals. A. ferrooxidans contains canonical copper resistance determinants present in other bacteria, such as CopA ATPases and RND efflux pumps, but these components do not entirely explain its high metal tolerance. The aim of this study was to find other possible copper resistance determinants in this bacterium. Transcriptional expression of A. ferrooxidans genes coding for a cytoplasmic CopZ-like copper-binding chaperone and the periplasmic copper-binding proteins rusticyanin and AcoP, which form part of an iron-oxidizing supercomplex, was found to increase when the microorganism was grown in the presence of copper. All of these proteins conferred more resistance to copper when expressed heterologously in a copper-sensitive Escherichia coli strain. This effect was absent when site-directed-mutation mutants of these proteins with altered copper-binding sites were used in this metal sensitivity assay. These results strongly suggest that the three copper-binding proteins analyzed here are copper resistance determinants in this extremophile and contribute to the high-level metal resistance of this industrially important biomining bacterium.
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Martinez P, Vera M, Bobadilla-Fazzini RA. Omics on bioleaching: current and future impacts. Appl Microbiol Biotechnol 2015; 99:8337-50. [PMID: 26278538 PMCID: PMC4768214 DOI: 10.1007/s00253-015-6903-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 07/27/2015] [Accepted: 07/30/2015] [Indexed: 11/28/2022]
Abstract
Bioleaching corresponds to the microbial-catalyzed process of conversion of insoluble metals into soluble forms. As an applied biotechnology globally used, it represents an extremely interesting field of research where omics techniques can be applied in terms of knowledge development, but moreover in terms of process design, control, and optimization. In this mini-review, the current state of genomics, proteomics, and metabolomics of bioleaching and the major impacts of these analytical methods at industrial scale are highlighted. In summary, genomics has been essential in the determination of the biodiversity of leaching processes and for development of conceptual and functional metabolic models. Proteomic impacts are mostly related to microbe-mineral interaction analysis, including copper resistance and biofilm formation. Early steps of metabolomics in the field of bioleaching have shown a significant potential for the use of metabolites as industrial biomarkers. Development directions are given in order to enhance the future impacts of the omics in biohydrometallurgy.
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Affiliation(s)
- Patricio Martinez
- BioSigma 'S.A.', Parque Industrial Los Libertadores, Lote 106, Colina, Chile
| | - Mario Vera
- Biofilm Centre, Aquatische Biotechnologie, Universität Duisburg-Essen, Universitätstraße 5, 45141, Essen, Germany
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System-level understanding of the potential acid-tolerance components of Acidithiobacillus thiooxidans ZJJN-3 under extreme acid stress. Extremophiles 2015; 19:1029-39. [DOI: 10.1007/s00792-015-0780-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 08/03/2015] [Indexed: 10/23/2022]
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Li TF, Painter RG, Ban B, Blake RC. The Multicenter Aerobic Iron Respiratory Chain of Acidithiobacillus ferrooxidans Functions as an Ensemble with a Single Macroscopic Rate Constant. J Biol Chem 2015; 290:18293-303. [PMID: 26041781 PMCID: PMC4513090 DOI: 10.1074/jbc.m115.657551] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 05/26/2015] [Indexed: 11/06/2022] Open
Abstract
Electron transfer reactions among three prominent colored proteins in intact cells of Acidithiobacillus ferrooxidans were monitored using an integrating cavity absorption meter that permitted the acquisition of accurate absorbance data in suspensions of cells that scattered light. The concentrations of proteins in the periplasmic space were estimated to be 350 and 25 mg/ml for rusticyanin and cytochrome c, respectively; cytochrome a was present as one molecule for every 91 nm(2) in the cytoplasmic membrane. All three proteins were rapidly reduced to the same relative extent when suspensions of live bacteria were mixed with different concentrations of ferrous ions at pH 1.5. The subsequent molecular oxygen-dependent oxidation of the multicenter respiratory chain occurred with a single macroscopic rate constant, regardless of the proteins' in vitro redox potentials or their putative positions in the aerobic iron respiratory chain. The crowded electron transport proteins in the periplasm of the organism constituted an electron conductive medium where the network of protein interactions functioned in a concerted fashion as a single ensemble with a standard reduction potential of 650 mV. The appearance of product ferric ions was correlated with the reduction levels of the periplasmic electron transfer proteins; the limiting first-order catalytic rate constant for aerobic respiration on iron was 7,400 s(-1). The ability to conduct direct spectrophotometric studies under noninvasive physiological conditions represents a new and powerful approach to examine the extent and rates of biological events in situ without disrupting the complexity of the live cellular environment.
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Affiliation(s)
- Ting-Feng Li
- From the College of Pharmacy, Xavier University of Louisiana, New Orleans, Louisiana 70125
| | - Richard G Painter
- From the College of Pharmacy, Xavier University of Louisiana, New Orleans, Louisiana 70125
| | - Bhupal Ban
- From the College of Pharmacy, Xavier University of Louisiana, New Orleans, Louisiana 70125
| | - Robert C Blake
- From the College of Pharmacy, Xavier University of Louisiana, New Orleans, Louisiana 70125
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37
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Liu HC, Xia JL, Nie ZY, Zhen XJ, Zhang LJ. Differential expression of extracellular thiol groups of moderately thermophilic Sulfobacillus thermosulfidooxidans and extremely thermophilic Acidianus manzaensis grown on S0 and Fe2+. Arch Microbiol 2015; 197:823-31. [DOI: 10.1007/s00203-015-1111-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 03/23/2015] [Accepted: 04/08/2015] [Indexed: 01/17/2023]
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Metal resistance in acidophilic microorganisms and its significance for biotechnologies. Appl Microbiol Biotechnol 2014; 98:8133-44. [PMID: 25104030 DOI: 10.1007/s00253-014-5982-2] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 07/18/2014] [Accepted: 07/22/2014] [Indexed: 10/24/2022]
Abstract
Extremely acidophilic microorganisms have an optimal pH of <3 and are found in all three domains of life. As metals are more soluble at acid pH, acidophiles are often challenged by very high metal concentrations. Acidophiles are metal-tolerant by both intrinsic, passive mechanisms as well as active systems. Passive mechanisms include an internal positive membrane potential that creates a chemiosmotic gradient against which metal cations must move, as well as the formation of metal sulfate complexes reducing the concentration of the free metal ion. Active systems include efflux proteins that pump metals out of the cytoplasm and conversion of the metal to a less toxic form. Acidophiles are exploited in a number of biotechnologies including biomining for sulfide mineral dissolution, biosulfidogenesis to produce sulfide that can selectively precipitate metals from process streams, treatment of acid mine drainage, and bioremediation of acidic metal-contaminated milieux. This review describes how acidophilic microorganisms tolerate extremely high metal concentrations in biotechnological processes and identifies areas of future work that hold promise for improving the efficiency of these applications.
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39
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Almárcegui RJ, Navarro CA, Paradela A, Albar JP, von Bernath D, Jerez CA. New copper resistance determinants in the extremophile acidithiobacillus ferrooxidans: a quantitative proteomic analysis. J Proteome Res 2014; 13:946-60. [PMID: 24380576 DOI: 10.1021/pr4009833] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Acidithiobacillus ferrooxidans is an extremophilic bacterium used in biomining processes to recover metals. The presence in A. ferrooxidans ATCC 23270 of canonical copper resistance determinants does not entirely explain the extremely high copper concentrations this microorganism is able to stand, suggesting the existence of other efficient copper resistance mechanisms. New possible copper resistance determinants were searched by using 2D-PAGE, real time PCR (qRT-PCR) and quantitative proteomics with isotope-coded protein labeling (ICPL). A total of 594 proteins were identified of which 120 had altered levels in cells grown in the presence of copper. Of this group of proteins, 76 were up-regulated and 44 down-regulated. The up-regulation of RND-type Cus systems and different RND-type efflux pumps was observed in response to copper, suggesting that these proteins may be involved in copper resistance. An overexpression of most of the genes involved in histidine synthesis and several of those annotated as encoding for cysteine production was observed in the presence of copper, suggesting a possible direct role for these metal-binding amino acids in detoxification. Furthermore, the up-regulation of putative periplasmic disulfide isomerases was also seen in the presence of copper, suggesting that they restore copper-damaged disulfide bonds to allow cell survival. Finally, the down-regulation of the major outer membrane porin and some ionic transporters was seen in A. ferrooxidans grown in the presence of copper, indicating a general decrease in the influx of the metal and other cations into the cell. Thus, A. ferrooxidans most likely uses additional copper resistance strategies in which cell envelope proteins are key components. This knowledge will not only help to understand the mechanism of copper resistance in this extreme acidophile but may help also to select the best fit members of the biomining community to attain more efficient industrial metal leaching processes.
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Affiliation(s)
- Rodrigo J Almárcegui
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile , Santiago Casilla 653 Chile
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40
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Zhu C, Liu L, Fan M, Liu L, Dai B, Yang J, Sun D. Microbial oxidation of graphite by Acidithiobacillus ferrooxidans CFMI-1. RSC Adv 2014. [DOI: 10.1039/c4ra09827g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A simple and environmentally-friendly bio-oxidation approach to produce graphite oxide nanosheets is described.
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Affiliation(s)
- Chunlin Zhu
- Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology
- Nanjing, China
| | - Linzhi Liu
- Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology
- Nanjing, China
| | - Mengmeng Fan
- Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology
- Nanjing, China
| | - Lin Liu
- Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology
- Nanjing, China
| | - Beibei Dai
- Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology
- Nanjing, China
| | - Jiazhi Yang
- Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology
- Nanjing, China
| | - Dongping Sun
- Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology
- Nanjing, China
- Key Laboratory for Soft Chemistry and Functional Materials of Ministry Education
- Nanjing University of Science and Technology
- Nanjing, China
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Heterodisulfide Reductase from Acidithiobacilli is a Key Component Involved in Metabolism of Reduced Inorganic Sulfur Compounds. ACTA ACUST UNITED AC 2013. [DOI: 10.4028/www.scientific.net/amr.825.194] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Heterodisulfide reductase (Hdr), is an iron-sulfur protein which in anaerobic methanogenic archaea catalyzes the reduction of the disulphide bond between coenzyme M and coenzyme B and is coupled to methane formation. In aerobic acidophilic chemolithotrophic bacteria (e.g., biomining bacteria) the function of this enzyme is unclear. Inspection of the genomic sequences of Acidithiobacillus ferrooxidans DSM 16786 and Acidithiobacillus thiooxidans DSM 17318 and reverse transcriptase-PCR results revealed a cluster of six co-transcribed genes, hdrC1, hdrB1, hdrA, orf1, hdrC2 and hdrB2, encoding proteins with high similarity to catalytic Hdr subunits. Additionally, microarray expression profiling and quantitative RT-PCR experiments demonstrated that the hdr genes of A.ferrooxidans and A. thiooxidans were highly expressed when bacteria are grown in the presence of sulfur and tetrathionate. Moreover, hdr genes in A. ferrooxidans were greatly up-regulated when this microorganism was grown in sulfur compared to ferrous medium. These results strongly support a role for Hdr in oxidative metabolism of reduced sulfur compounds in aerobic chemolithotrophic bacteria.
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Xia JL, Liu HC, Nie ZY, Peng AA, Zhen XJ, Yang Y, Zhang XL. Synchrotron radiation based STXM analysis and micro-XRF mapping of differential expression of extracellular thiol groups by Acidithiobacillus ferrooxidans grown on Fe2+ and S0. J Microbiol Methods 2013; 94:257-61. [DOI: 10.1016/j.mimet.2013.06.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 06/17/2013] [Accepted: 06/24/2013] [Indexed: 11/26/2022]
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Top-Down Characterization of the Post-Translationally Modified Intact Periplasmic Proteome from the Bacterium Novosphingobium aromaticivorans. INTERNATIONAL JOURNAL OF PROTEOMICS 2013; 2013:279590. [PMID: 23555055 PMCID: PMC3608174 DOI: 10.1155/2013/279590] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Revised: 01/31/2013] [Accepted: 02/04/2013] [Indexed: 11/17/2022]
Abstract
The periplasm of Gram-negative bacteria is a dynamic and physiologically important subcellular compartment where the constant exposure to potential environmental insults amplifies the need for proper protein folding and modifications. Top-down proteomics analysis of the periplasmic fraction at the intact protein level provides unrestricted characterization and annotation of the periplasmic proteome, including the post-translational modifications (PTMs) on these proteins. Here, we used single-dimension ultra-high pressure liquid chromatography coupled with the Fourier transform mass spectrometry (FTMS) to investigate the intact periplasmic proteome of Novosphingobium aromaticivorans. Our top-down analysis provided the confident identification of 55 proteins in the periplasm and characterized their PTMs including signal peptide removal, N-terminal methionine excision, acetylation, glutathionylation, pyroglutamate, and disulfide bond formation. This study provides the first experimental evidence for the expression and periplasmic localization of many hypothetical and uncharacterized proteins and the first unrestrictive, large-scale data on PTMs in the bacterial periplasm.
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44
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Vera M, Krok B, Bellenberg S, Sand W, Poetsch A. Shotgun proteomics study of early biofilm formation process of Acidithiobacillus ferrooxidans ATCC 23270 on pyrite. Proteomics 2013; 13:1133-44. [PMID: 23319327 DOI: 10.1002/pmic.201200386] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Revised: 12/17/2012] [Accepted: 12/18/2012] [Indexed: 12/15/2022]
Abstract
Acidithiobacillus ferrooxidans is a chemolithoautotrophic, mesophilic Gram-negative bacterium able to oxidize ferrous iron, sulfur, and metal sulfides. It forms monolayer biofilms where extracellular polymeric substances are essential for cell attachment and metal sulfide leaching. High-throughput proteomics has been applied to study the early process of biofilm formation on pyrite by At. ferrooxidans ATCC 23270. After 24 h contact with the mineral, planktonic and sessile (biofilm) cell subpopulations were separated and proteins extracted. In total, 1319 proteins were detected in both samples. Sixty-two of these were found to be increased in biofilms. Additionally, 25 proteins were found to be decreased in the biofilm cell subpopulation. Three transcriptional factors were found to be increased or decreased among both cell subpopulations, suggesting their potential involvement in the regulation of these processes. Although no significant differences were observed for the known proteins related to ferrous iron and sulfur oxidation pathways among both cell subpopulations, the results presented here show that the early steps of At. ferrooxidans biofilm formation consist of a set of metabolic adaptations following cell attachment to the mineral surface. Functions such as extracellular polymeric substances biosynthesis seem to be pivotal. This first high-throughput proteomic study may also contribute to the annotation of several unknown At. ferrooxidans proteins found.
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Affiliation(s)
- Mario Vera
- Biofilm Centre, University of Duisburg-Essen, Duisburg-Essen, Germany
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45
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Anaerobic sulfur metabolism coupled to dissimilatory iron reduction in the extremophile Acidithiobacillus ferrooxidans. Appl Environ Microbiol 2013; 79:2172-81. [PMID: 23354702 DOI: 10.1128/aem.03057-12] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Gene transcription (microarrays) and protein levels (proteomics) were compared in cultures of the acidophilic chemolithotroph Acidithiobacillus ferrooxidans grown on elemental sulfur as the electron donor under aerobic and anaerobic conditions, using either molecular oxygen or ferric iron as the electron acceptor, respectively. No evidence supporting the role of either tetrathionate hydrolase or arsenic reductase in mediating the transfer of electrons to ferric iron (as suggested by previous studies) was obtained. In addition, no novel ferric iron reductase was identified. However, data suggested that sulfur was disproportionated under anaerobic conditions, forming hydrogen sulfide via sulfur reductase and sulfate via heterodisulfide reductase and ATP sulfurylase. Supporting physiological evidence for H2S production came from the observation that soluble Cu(2+) included in anaerobically incubated cultures was precipitated (seemingly as CuS). Since H(2)S reduces ferric iron to ferrous in acidic medium, its production under anaerobic conditions indicates that anaerobic iron reduction is mediated, at least in part, by an indirect mechanism. Evidence was obtained for an alternative model implicating the transfer of electrons from S(0) to Fe(3+) via a respiratory chain that includes a bc(1) complex and a cytochrome c. Central carbon pathways were upregulated under aerobic conditions, correlating with higher growth rates, while many Calvin-Benson-Bassham cycle components were upregulated during anaerobic growth, probably as a result of more limited access to carbon dioxide. These results are important for understanding the role of A. ferrooxidans in environmental biogeochemical metal cycling and in industrial bioleaching operations.
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46
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Ferrous iron oxidation by sulfur-oxidizing Acidithiobacillus ferrooxidans and analysis of the process at the levels of transcription and protein synthesis. Antonie van Leeuwenhoek 2013; 103:905-19. [DOI: 10.1007/s10482-012-9872-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 12/24/2012] [Indexed: 11/26/2022]
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47
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Mineral respiration under extreme acidic conditions: from a supramolecular organization to a molecular adaptation in Acidithiobacillus ferrooxidans. Biochem Soc Trans 2012; 40:1324-9. [DOI: 10.1042/bst20120141] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Acidithiobacillus ferrooxidans is an acidophilic chemolithoautotrophic Gram-negative bacterium that can derive energy from the oxidation of ferrous iron at pH 2 using oxygen as electron acceptor. The study of this bacterium has economic and fundamental biological interest because of its use in the industrial extraction of copper and uranium from ores. For this reason, its respiratory chain has been analysed in detail in recent years. Studies have shown the presence of a functional supercomplex that spans the outer and the inner membranes and allows a direct electron transfer from the extracellular Fe2+ ions to the inner membrane cytochrome c oxidase. Iron induces the expression of two operons encoding proteins implicated in this complex as well as in the regeneration of the reducing power. Most of these are metalloproteins that have been characterized biochemically, structurally and biophysically. For some of them, the molecular basis of their adaptation to the periplasmic acidic environment has been described. Modifications in the metal surroundings have been highlighted for cytochrome c and rusticyanin, whereas, for the cytochrome c oxidase, an additional partner that maintains its stability and activity has been demonstrated recently.
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48
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Tetrathionate-forming thiosulfate dehydrogenase from the acidophilic, chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans. Appl Environ Microbiol 2012; 79:113-20. [PMID: 23064330 DOI: 10.1128/aem.02251-12] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thiosulfate dehydrogenase is known to play a significant role in thiosulfate oxidation in the acidophilic, obligately chemolithoautotroph, Acidithiobacillus ferrooxidans. Enzyme activity measured using ferricyanide as the electron acceptor was detected in cell extracts of A. ferrooxidans ATCC 23270 grown on tetrathionate or sulfur, but no activity was detected in ferrous iron-grown cells. The enzyme was enriched 63-fold from cell extracts of tetrathionate-grown cells. Maximum enzyme activity (13.8 U mg(-1)) was observed at pH 2.5 and 70°C. The end product of the enzyme reaction was tetrathionate. The enzyme reduced neither ubiquinone nor horse heart cytochrome c, which serves as an electron acceptor. A major protein with a molecular mass of ∼25 kDa was detected in the partially purified preparation. Heme was not detected in the preparation, according to the results of spectroscopic analysis and heme staining. The open reading frame of AFE_0042 was identified by BLAST by using the N-terminal amino acid sequence of the protein. The gene was found within a region that was previously noted for sulfur metabolism-related gene clustering. The recombinant protein produced in Escherichia coli had a molecular mass of ∼25 kDa and showed thiosulfate dehydrogenase activity, with maximum enzyme activity (6.5 U mg(-1)) observed at pH 2.5 and 50°C.
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49
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Dopson M, Johnson DB. Biodiversity, metabolism and applications of acidophilic sulfur-metabolizing microorganisms. Environ Microbiol 2012; 14:2620-31. [PMID: 22510111 DOI: 10.1111/j.1462-2920.2012.02749.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Extremely acidic, sulfur-rich environments can be natural, such as solfatara fields in geothermal and volcanic areas, or anthropogenic, such as acid mine drainage waters. Many species of acidophilic bacteria and archaea are known to be involved in redox transformations of sulfur, using elemental sulfur and inorganic sulfur compounds as electron donors or acceptors in reactions involving between one and eight electrons. This minireview describes the nature and origins of acidic, sulfur-rich environments, the biodiversity of sulfur-metabolizing acidophiles, and how sulfur is metabolized and assimilated by acidophiles under aerobic and anaerobic conditions. Finally, existing and developing technologies that harness the abilities of sulfur-oxidizing and sulfate-reducing acidophiles to extract and capture metals, and to remediate sulfur-polluted waste waters are outlined.
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Affiliation(s)
- Mark Dopson
- School of Natural Sciences, Linnaeus University, Kalmar, Sweden
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Development of a markerless gene replacement system for Acidithiobacillus ferrooxidans and construction of a pfkB mutant. Appl Environ Microbiol 2011; 78:1826-35. [PMID: 22210219 DOI: 10.1128/aem.07230-11] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The extremely acidophilic, chemolithoautotrophic Acidithiobacillus ferrooxidans is an important bioleaching bacterium of great value in the metallurgical industry and environmental protection. In this report, a mutagenesis system based on the homing endonuclease I-SceI was developed to produce targeted, unmarked gene deletions in the strain A. ferrooxidans ATCC 23270. A targeted phosphofructokinase (PFK) gene (pfkB) mutant of A. ferrooxidans ATCC 23270 was constructed by homologous recombination and identified by PCR with specific primers as well as Southern blot analysis. This potential pfkB gene (AFE_1807) was also characterized by expression in PFK-deficient Escherichia coli cells, and heteroexpression of the PFKB protein demonstrated that it had functional PFK activity, though it was significantly lower (about 800-fold) than that of phosphofructokinase-2 (PFK-B) expressed by the pfkB gene from E. coli K-12. The function of the potential PFKB protein in A. ferrooxidans was demonstrated by comparing the properties of the pfkB mutant with those of the wild type. The pfkB mutant strain displayed a relatively reduced growth capacity in S(0) medium (0.5% [wt/vol] elemental sulfur in 9K basal salts solution adjusted to pH 3.0 with H(2)SO(4)), but the mutation did not completely prevent A. ferrooxidans from assimilating exogenous glucose. The transcriptional analysis of some related genes in central carbohydrate metabolism in the wild-type and mutant strains with or without supplementation of glucose was carried out by quantitative reverse transcription-PCR. This report suggests that the markerless mutagenesis strategy could serve as a model for functional studies of other genes of interest from A. ferrooxidans and multiple mutations could be made in a single A. ferrooxidans strain.
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