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Olaya‐Abril A, Biełło K, Rodríguez‐Caballero G, Cabello P, Sáez LP, Moreno‐Vivián C, Luque‐Almagro VM, Roldán MD. Bacterial tolerance and detoxification of cyanide, arsenic and heavy metals: Holistic approaches applied to bioremediation of industrial complex wastes. Microb Biotechnol 2024; 17:e14399. [PMID: 38206076 PMCID: PMC10832572 DOI: 10.1111/1751-7915.14399] [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: 07/11/2023] [Revised: 12/19/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024] Open
Abstract
Cyanide is a highly toxic compound that is found in wastewaters generated from different industrial activities, such as mining or jewellery. These residues usually contain high concentrations of other toxic pollutants like arsenic and heavy metals that may form different complexes with cyanide. To develop bioremediation strategies, it is necessary to know the metabolic processes involved in the tolerance and detoxification of these pollutants, but most of the current studies are focused on the characterization of the microbial responses to each one of these environmental hazards individually, and the effect of co-contaminated wastes on microbial metabolism has been hardly addressed. This work summarizes the main strategies developed by bacteria to alleviate the effects of cyanide, arsenic and heavy metals, analysing interactions among these toxic chemicals. Additionally, it is discussed the role of systems biology and synthetic biology as tools for the development of bioremediation strategies of complex industrial wastes and co-contaminated sites, emphasizing the importance and progress derived from meta-omic studies.
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Affiliation(s)
- Alfonso Olaya‐Abril
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Karolina Biełło
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Gema Rodríguez‐Caballero
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Purificación Cabello
- Departamento de Botánica, Ecología y Fisiología Vegetal, Edificio Celestino Mutis, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Lara P. Sáez
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Conrado Moreno‐Vivián
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Víctor Manuel Luque‐Almagro
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - María Dolores Roldán
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
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Recalde A, González-Madrid G, Acevedo-López J, Jerez CA. Sessile Lifestyle Offers Protection against Copper Stress in Saccharolobus solfataricus. Microorganisms 2023; 11:1421. [PMID: 37374923 DOI: 10.3390/microorganisms11061421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 05/22/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023] Open
Abstract
Some archaea from the genus Sulfolobus are important for bioleaching of copper, where metal resistant microorganisms are required. Biofilm generation is one of the ways microorganisms cope with some stimuli in nature, including heavy metals. The response to external factors, particularly in the biofilm form of life, is still underexplored in archaea. To explore how model thermoacidophilic archaeon Saccharolobus solfataricus faces copper stress during this lifestyle, changes in biofilms were studied using crystal violet staining, confocal fluorescence microscopy, and qPCR approaches. It was found that biofilm formation reached a maximum at 0.5 mM Cu, before starting to decrease at higher metal concentrations. The morphology of biofilms at 0.5 mM Cu was observed to be different, displaying lower thickness, different sugar patterns, and higher amounts of cells compared to standard growing conditions. Furthermore, copA, which is responsive to intracellular Cu concentration, was downregulated in biofilm cells when compared with planktonic cells exposed to the same metal concentration. The latest results suggests that cells in biofilms are less exposed to Cu than those in planktonic culture. In a PolyP-deficient strain, Cu was not able to induce biofilm formation at 0.5 mM. In summary, the findings reported here suggest that the biofilm form of life confers S. solfataricus advantages to face stress caused by Cu.Biofilm formation remains a relatively unexplored topic in archaeal research. Therefore, this knowledge in model organisms such as S. solfataricus, and how they use it to face stress, could be of great importance to engineer organisms with improved capabilities to be applied in biotechnological processes, such as bioleaching of metals.
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Affiliation(s)
- Alejandra Recalde
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, 8330111 Santiago, Chile
- Molecular Biology of Archaea, Institute of Biology II-Microbiology, University of Freiburg, 79104 Freiburg, Germany
| | - Gabriela González-Madrid
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, 8330111 Santiago, Chile
| | - José Acevedo-López
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, 8330111 Santiago, Chile
| | - Carlos A Jerez
- Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, University of Chile, 8330111 Santiago, Chile
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Molecular Insights into a Novel Cu(I)-Sensitive ArsR/SmtB Family Repressor in Extremophile Acidithiobacillus caldus. Appl Environ Microbiol 2023; 89:e0126622. [PMID: 36602357 PMCID: PMC9888290 DOI: 10.1128/aem.01266-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Acidithiobacillus caldus is a common bioleaching bacterium that is inevitably exposed to extreme copper stress in leachates. The ArsR/SmtB family of metalloregulatory repressors regulates homeostasis and resistance in bacteria by specifically responding to metals. Here, we characterized A. caldus Cu(I)-sensitive repressor (AcsR) and gained molecular insights into this new member of the ArsR/SmtB family. Transcriptional analysis indicated that the promoter (PIII) of acsR was highly active in Escherichia coli but inhibited upon AcsR binding to the PIII-acsR region. Size exclusion chromatography and circular dichroism spectra revealed that CuI-AcsR shared an identical assembly state with apo-AcsR, as a dimer with fewer α helices, more extended strands, and more β turns. Mutation of the cysteine site in AcsR did not affect its assembly state. Copper(I) titrations revealed that apo-AcsR bound two Cu(I) molecules per monomer in vitro with an average dissociation constant (KD) for bicinchoninic acid competition of 2.55 × 10-9 M. Site-directed mutation of putative Cu(I)-binding ligands in AcsR showed that replacing Cys64 with Ala reduces copper binding ability from two Cu(I) molecules per monomer to one, with an average KD of 6.05 × 10-9 M. Electrophoretic mobility shift assays revealed that apo-AcsR has high affinity for the 12-2-12 imperfect inverted repeats P2245 and P2270 in the acsR gene cluster and that Cu-loaded AcsR had lower affinity for DNA fragments than apo-AcsR. We developed a hypothetical working model of AcsR to better understand Cu resistance mechanisms in A. caldus. IMPORTANCE Copper (Cu) resistance among various microorganisms is attracting interest. The chemolithoautotrophic bacterium A. caldus, which can tolerate extreme copper stress (≥10 g/L Cu ions), is typically used to bioleach chalcopyrite (CuFeS2). Understanding of Cu resistance in A. caldus is limited due to scant investigation and the absence of efficient gene manipulation tools. Here, we characterized a new member of the ArsR/SmtB family of prokaryotic metalloregulatory transcriptional proteins that repress operons linked to stress-inducing concentrations of heavy metal ions. This protein can bind two Cu(I) molecules per monomer and negatively regulate its gene cluster. Members of the ArsR/SmtB family have not been investigated in A. caldus until now. The discovery of this novel protein enriches understanding of Cu homeostasis in A. caldus.
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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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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] [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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