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Jillian F Banfield - One of the best experts on this subject based on the ideXlab platform.
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New Group in the Leptospirillum Clade: Cultivation-Independent Community Genomics, Proteomics, and Transcriptomics of the New Species “Leptospirillum Group IV UBA BS”
Applied and environmental microbiology, 2013Co-Authors: Daniela S. Aliaga Goltsman, Mauna Dasari, Brian C. Thomas, Manesh B Shah, Nathan C Verberkmoes, Robert L. Hettich, Jillian F BanfieldAbstract:Leptospirillum spp. are widespread members of acidophilic microbial communities that catalyze ferrous iron oxidation, thereby increasing sulfide mineral dissolution rates. These bacteria play important roles in environmental acidification and are harnessed for bioleaching-based metal recovery. Known members of the Leptospirillum clade of the Nitrospira phylum are Leptospirillum ferrooxidans (group I), Leptospirillum ferriphilum and “Leptospirillum rubarum” (group II), and Leptospirillum ferrodiazotrophum (group III). In the Richmond Mine acid mine drainage (AMD) system, biofilm formation is initiated by L. rubarum; L. ferrodiazotrophum appears in later developmental stages. Here we used community metagenomic data from unusual, thick floating biofilms to identify distinguishing metabolic traits in a rare and uncultivated community member, the new species “Leptospirillum group IV UBA BS.” These biofilms typically also contain a variety of Archaea, Actinobacteria, and a few other Leptospirillum spp. The Leptospirillum group IV UBA BS species shares 98% 16S rRNA sequence identity and 70% average amino acid identity between orthologs with its closest relative, L. ferrodiazotrophum. The presence of nitrogen fixation and reverse tricarboxylic acid (TCA) cycle proteins suggest an autotrophic metabolism similar to that of L. ferrodiazotrophum, while hydrogenase proteins suggest anaerobic metabolism. Community transcriptomic and proteomic analyses demonstrate expression of a multicopper oxidase unique to this species, as well as hydrogenases and core metabolic genes. Results suggest that the Leptospirillum group IV UBA BS species might play important roles in carbon fixation, nitrogen fixation, hydrogen metabolism, and iron oxidation in some acidic environments.
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Deuterium-exchange metabolomics identifies N-methyl lyso phosphatidylethanolamines as abundant lipids in acidophilic mixed microbial communities
Metabolomics, 2012Co-Authors: Curt R. Fischer, Paul Wilmes, Benjamin P. Bowen, Trent R. Northen, Jillian F BanfieldAbstract:Natural microbial communities are extremely diverse and contain uncharacterized but functionally important small molecules. By coupling a deuterium (D) labeling technique to high mass accuracy untargeted liquid chromatography-electrospray ionization-mass spectrometry (LC–ESI–MS) metabolomic analysis, we found that natural acidophilic microbial biofilms dominated by bacteria of the genus Leptospirillum contained unusual lyso phosphatidylethanolamine (PE) lipids in high abundance (more than 10 nmol/mg of dry biomass). The unusual polar head group structure of these lipids is similar to lipids found in phylogenetically unrelated acidophilic chemoautolithotrophs and may be related to the affinity of these lipids for iron and calcium ions. Correlations of lyso phospholipid and proteome abundance patterns suggest a link between the lyso phospholipids and the UBA-type substrain of Leptospirillum group II. By combining untargeted metabolomics with D exchange we demonstrate the ability to identify cryptic but biologically functional small molecules in mixed microbial communities.
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Population Genomic Analysis of Strain Variation in Leptospirillum Group II Bacteria Involved in Acid Mine Drainage Formation
PLoS biology, 2008Co-Authors: Sheri L. Simmons, Daniela S. Aliaga Goltsman, Vincent J. Denef, Genevieve Dibartolo, Michael P. Thelen, Jillian F BanfieldAbstract:Deeply sampled community genomic (metagenomic) datasets enable comprehensive analysis of heterogeneity in natural microbial populations. In this study, we used sequence data obtained from the dominant member of a low-diversity natural chemoautotrophic microbial community to determine how coexisting closely related individuals differ from each other in terms of gene sequence and gene content, and to uncover evidence of evolutionary processes that occur over short timescales. DNA sequence obtained from an acid mine drainage biofilm was reconstructed, taking into account the effects of strain variation, to generate a nearly complete genome tiling path for a Leptospirillum group II species closely related to L. ferriphilum (sampling depth ∼20×). The population is dominated by one sequence type, yet we detected evidence for relatively abundant variants (>99.5% sequence identity to the dominant type) at multiple loci, and a few rare variants. Blocks of other Leptospirillum group II types (∼94% sequence identity) have recombined into one or more variants. Variant blocks of both types are more numerous near the origin of replication. Heterogeneity in genetic potential within the population arises from localized variation in gene content, typically focused in integrated plasmid/phage-like regions. Some laterally transferred gene blocks encode physiologically important genes, including quorum-sensing genes of the LuxIR system. Overall, results suggest inter- and intrapopulation genetic exchange involving distinct parental genome types and implicate gain and loss of phage and plasmid genes in recent evolution of this Leptospirillum group II population. Population genetic analyses of single nucleotide polymorphisms indicate variation between closely related strains is not maintained by positive selection, suggesting that these regions do not represent adaptive differences between strains. Thus, the most likely explanation for the observed patterns of polymorphism is divergence of ancestral strains due to geographic isolation, followed by mixing and subsequent recombination.
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Genome-Directed Isolation of the Key Nitrogen Fixer Leptospirillum ferrodiazotrophum sp. nov. from an Acidophilic Microbial Community
Applied and environmental microbiology, 2005Co-Authors: Gene W. Tyson, Brett J Baker, Eric E. Allen, Philip Hugenholtz, Jillian F BanfieldAbstract:Analysis of assembled random shotgun sequence data from a low-diversity, subsurface acid mine drainage (AMD) biofilm revealed a single nif operon. This was found on a genome fragment belonging to a member of Leptospirillum group III, a lineage in the Nitrospirae phylum with no cultivated representatives. Based on the prediction that this organism is solely responsible for nitrogen fixation in the community, we pursued a selective isolation strategy to obtain the organism in pure culture. An AMD biofilm sample naturally abundant in Leptospirillum group III cells was homogenized, filtered, and serially diluted into a nitrogen-free liquid medium. The resulting culture in the terminal dilution grew autotrophically to a maximum cell density of ∼106 cells/ml, oxidizing ferrous iron as the sole energy source. 16S rRNA-internal transcribed spacer region clone library analysis confirmed that the isolate is a member of Leptospirillum group III and that the culture is axenic. We propose the name Leptospirillum ferrodiazotrophum sp. nov. for this iron-oxidizing, free-living diazotroph. This study highlights how environmental sequence data can provide insights for culturing previously uncultured microorganisms.
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Community structure and metabolism through reconstruction of microbial genomes from the environment
Nature, 2004Co-Authors: Gene W. Tyson, Rachna J. Ram, Paul M. Richardson, Vladimirovich Valery Solovyev, Edward M. Rubin, Jarrod Chapman, Daniel S Rokhsar, Eric E. Allen, Philip Hugenholtz, Jillian F BanfieldAbstract:Microbial communities are vital in the functioning of all ecosystems; however, most microorganisms are uncultivated, and their roles in natural systems are unclear. Here, using random shotgun sequencing of DNA from a natural acidophilic biofilm, we report reconstruction of near-complete genomes of Leptospirillum group II and Ferroplasma type II, and partial recovery of three other genomes. This was possible because the biofilm was dominated by a small number of species populations and the frequency of genomic rearrangements and gene insertions or deletions was relatively low. Because each sequence read came from a different individual, we could determine that single-nucleotide polymorphisms are the predominant form of heterogeneity at the strain level. The Leptospirillum group II genome had remarkably few nucleotide polymorphisms, despite the existence of low-abundance variants. The Ferroplasma type II genome seems to be a composite from three ancestral strains that have undergone homologous recombination to form a large population of mosaic genomes. Analysis of the gene complement for each organism revealed the pathways for carbon and nitrogen fixation and energy generation, and provided insights into survival strategies in an extreme environment.
Gloria Levicán - One of the best experts on this subject based on the ideXlab platform.
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Deciphering the role of multiple thioredoxin fold proteins of Leptospirillum sp. in oxidative stress tolerance
International journal of molecular sciences, 2020Co-Authors: Daniela González, Omar Orellana, Renato Chávez, Pamela Álamos, Matías Rivero, Javiera Norambuena, Gloria LevicánAbstract: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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Cobalamin Protection against Oxidative Stress in the Acidophilic Iron-oxidizing Bacterium Leptospirillum Group II CF-1
Frontiers in microbiology, 2016Co-Authors: Alonso Ferrer, Omar Orellana, Renato Chávez, Javiera Norambuena, Javier Rivera, Claudia Zapata, Álvaro Sandoval, Gloria LevicánAbstract:Members of the genus Leptospirillum are aerobic iron-oxidizing bacteria belonging to the phylum Nitrospira. They are important members of microbial communities that catalyze the biomining of sulfidic ores, thereby solubilizing metal ions. These microorganisms live under extremely acidic and metal-loaded environments and thus must tolerate high concentrations of reactive oxygen species. Cobalamin (vitamin B12) is a cobalt-containing tetrapyrrole cofactor involved in intramolecular rearrangement reactions and has recently been suggested to be an intracellular antioxidant. In this work, we investigated the effect of the exogenous addition of cobalamin on oxidative stress parameters in Leptospirillum group II strain CF-1. Our results revealed that the external supplementation of cobalamin reduces the levels of intracellular reactive oxygen species and the damage to biomolecules, and also stimulates the growth and survival of cells exposed to oxidative stress exerted by ferric ion, hydrogen peroxide, chromate and diamide. Furthermore, exposure of strain CF-1 to oxidative stress elicitors resulted in the transcriptional activation of the cbiA gene encoding CbiA of the cobalamin biosynthetic pathway. Altogether, these data suggest that cobalamin plays an important role in redox protection of Leptospirillum strain CF-1, supporting survival of this microorganism under extremely oxidative environmental conditions. Understanding the mechanisms underlying the protective effect of cobalamin against oxidative stress may help to develop strategies to make biomining processes more effective.
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Complete genome sequence of the bioleaching bacterium Leptospirillum sp. group II strain CF-1.
Journal of biotechnology, 2016Co-Authors: Alonso Ferrer, Boyke Bunk, Cathrin Spröer, Rebekka Biedendieck, Natalia Valdés, Martina Jahn, Dieter Jahn, Omar Orellana, Gloria LevicánAbstract:We describe the complete genome sequence of Leptospirillum sp. group II strain CF-1, an acidophilic bioleaching bacterium isolated from an acid mine drainage (AMD). This work provides data to gain insights about adaptive response of Leptospirillum spp. to the extreme conditions of bioleaching environments.
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Comparative genomic analysis reveals novel facts about Leptospirillum spp. cytochromes.
Journal of molecular microbiology and biotechnology, 2012Co-Authors: Gloria Levicán, Omar Orellana, Mercedes Moreno-paz, Manuel J. Gómez, Renato Chávez, Víctor ParroAbstract:Chemolithoautotrophic acidophilic bacteria, which belong to the genus Leptospirillum , can only grow with Fe(II) as electron donor and oxygen as an electron acceptor. Members of this
Daniela S. Aliaga Goltsman - One of the best experts on this subject based on the ideXlab platform.
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New Group in the Leptospirillum Clade: Cultivation-Independent Community Genomics, Proteomics, and Transcriptomics of the New Species “Leptospirillum Group IV UBA BS”
Applied and environmental microbiology, 2013Co-Authors: Daniela S. Aliaga Goltsman, Mauna Dasari, Brian C. Thomas, Manesh B Shah, Nathan C Verberkmoes, Robert L. Hettich, Jillian F BanfieldAbstract:Leptospirillum spp. are widespread members of acidophilic microbial communities that catalyze ferrous iron oxidation, thereby increasing sulfide mineral dissolution rates. These bacteria play important roles in environmental acidification and are harnessed for bioleaching-based metal recovery. Known members of the Leptospirillum clade of the Nitrospira phylum are Leptospirillum ferrooxidans (group I), Leptospirillum ferriphilum and “Leptospirillum rubarum” (group II), and Leptospirillum ferrodiazotrophum (group III). In the Richmond Mine acid mine drainage (AMD) system, biofilm formation is initiated by L. rubarum; L. ferrodiazotrophum appears in later developmental stages. Here we used community metagenomic data from unusual, thick floating biofilms to identify distinguishing metabolic traits in a rare and uncultivated community member, the new species “Leptospirillum group IV UBA BS.” These biofilms typically also contain a variety of Archaea, Actinobacteria, and a few other Leptospirillum spp. The Leptospirillum group IV UBA BS species shares 98% 16S rRNA sequence identity and 70% average amino acid identity between orthologs with its closest relative, L. ferrodiazotrophum. The presence of nitrogen fixation and reverse tricarboxylic acid (TCA) cycle proteins suggest an autotrophic metabolism similar to that of L. ferrodiazotrophum, while hydrogenase proteins suggest anaerobic metabolism. Community transcriptomic and proteomic analyses demonstrate expression of a multicopper oxidase unique to this species, as well as hydrogenases and core metabolic genes. Results suggest that the Leptospirillum group IV UBA BS species might play important roles in carbon fixation, nitrogen fixation, hydrogen metabolism, and iron oxidation in some acidic environments.
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Community Genomic and Proteomic Analyses of Chemoautotrophic Iron-Oxidizing “Leptospirillum rubarum” (Group II) and “Leptospirillum ferrodiazotrophum” (Group III) Bacteria in Acid Mine Drainage Biofilms
Applied and environmental microbiology, 2009Co-Authors: Daniela S. Aliaga Goltsman, Nathan C Verberkmoes, Vincent J. Denef, Steven W. Singer, Mark Lefsrud, Ryan S. Mueller, Gregory J. Dick, Christine L. Sun, Korin E. Wheeler, Adam ZemlaAbstract:We analyzed near-complete population (composite) genomic sequences for coexisting acidophilic iron-oxidizing Leptospirillum group II and III bacteria (phylum Nitrospirae) and an extrachromosomal plasmid from a Richmond Mine, Iron Mountain, CA, acid mine drainage biofilm. Community proteomic analysis of the genomically characterized sample and two other biofilms identified 64.6% and 44.9% of the predicted proteins of Leptospirillum groups II and III, respectively, and 20% of the predicted plasmid proteins. The bacteria share 92% 16S rRNA gene sequence identity and >60% of their genes, including integrated plasmid-like regions. The extrachromosomal plasmid carries conjugation genes with detectable sequence similarity to genes in the integrated conjugative plasmid, but only those on the extrachromosomal element were identified by proteomics. Both bacterial groups have genes for community-essential functions, including carbon fixation and biosynthesis of vitamins, fatty acids, and biopolymers (including cellulose); proteomic analyses reveal these activities. Both Leptospirillum types have multiple pathways for osmotic protection. Although both are motile, signal transduction and methyl-accepting chemotaxis proteins are more abundant in Leptospirillum group III, consistent with its distribution in gradients within biofilms. Interestingly, Leptospirillum group II uses a methyl-dependent and Leptospirillum group III a methyl-independent response pathway. Although only Leptospirillum group III can fix nitrogen, these proteins were not identified by proteomics. The abundances of core proteins are similar in all communities, but the abundance levels of unique and shared proteins of unknown function vary. Some proteins unique to one organism were highly expressed and may be key to the functional and ecological differentiation of Leptospirillum groups II and III.
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Community genomic and proteomic analysis of chemoautotrophic, iron-oxidizing "Leptospirillum rubarum" (Group II) and Leptospirillum ferrodiazotrophum (Group III) in acid mine drainage biofilms
Applied Microbiology and Biotechnology, 2009Co-Authors: Daniela S. Aliaga Goltsman, Nathan C Verberkmoes, Vincent J. Denef, Steven W. Singer, Mark Lefsrud, Ryan S. Mueller, Gregory J. Dick, Christine L. Sun, Korin E. Wheeler, Adam ZelmaAbstract:We analyzed near-complete population (composite) genomic sequences for coexisting acidophilic iron-oxidizing Leptospirillum Groups II and III bacteria (phylum Nitrospirae) and an extrachromosomal plasmid from a Richmond Mine, CA acid mine drainage (AMD) biofilm. Community proteomic analysis of the genomically characterized sample and two other biofilms identified 64.6% and 44.9% of the predicted proteins of Leptospirillum Groups II and III, respectively and 20% of the predicted plasmid proteins. The bacteria share 92% 16S rRNA gene sequence identity and > 60% of their genes, including integrated plasmid-like regions. The extrachromosomal plasmid encodes conjugation genes with detectable sequence similarity to genes in the integrated conjugative plasmid, but only those on the extrachromosomal element were identified by proteomics. Both bacteria have genes for community-essential functions, including carbon fixation, biosynthesis of vitamins, fatty acids and biopolymers (including cellulose); proteomic analyses reveal these activities. Both Leptospirillum types have multiple pathways for osmotic protection. Although both are motile, signal transduction and methyl-accepting chemotaxis proteins are more abundant in Leptospirillum Group III, consistent with its distribution in gradients within biofilms. Interestingly, Leptospirillum Group II uses a methyl-dependent and Leptospirillum Group III a methyl-independent response pathway. Although only Leptospirillum Group III can fix nitrogen, these proteins were not identifiedmore » by proteomics. Abundances of core proteins are similar in all communities, but abundance levels of unique and shared proteins of unknown function vary. Some proteins unique to one organism were highly expressed and may be key to the functional and ecological differentiation of Leptospirillum Groups II and III.« less
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Population Genomic Analysis of Strain Variation in Leptospirillum Group II Bacteria Involved in Acid Mine Drainage Formation
PLoS biology, 2008Co-Authors: Sheri L. Simmons, Daniela S. Aliaga Goltsman, Vincent J. Denef, Genevieve Dibartolo, Michael P. Thelen, Jillian F BanfieldAbstract:Deeply sampled community genomic (metagenomic) datasets enable comprehensive analysis of heterogeneity in natural microbial populations. In this study, we used sequence data obtained from the dominant member of a low-diversity natural chemoautotrophic microbial community to determine how coexisting closely related individuals differ from each other in terms of gene sequence and gene content, and to uncover evidence of evolutionary processes that occur over short timescales. DNA sequence obtained from an acid mine drainage biofilm was reconstructed, taking into account the effects of strain variation, to generate a nearly complete genome tiling path for a Leptospirillum group II species closely related to L. ferriphilum (sampling depth ∼20×). The population is dominated by one sequence type, yet we detected evidence for relatively abundant variants (>99.5% sequence identity to the dominant type) at multiple loci, and a few rare variants. Blocks of other Leptospirillum group II types (∼94% sequence identity) have recombined into one or more variants. Variant blocks of both types are more numerous near the origin of replication. Heterogeneity in genetic potential within the population arises from localized variation in gene content, typically focused in integrated plasmid/phage-like regions. Some laterally transferred gene blocks encode physiologically important genes, including quorum-sensing genes of the LuxIR system. Overall, results suggest inter- and intrapopulation genetic exchange involving distinct parental genome types and implicate gain and loss of phage and plasmid genes in recent evolution of this Leptospirillum group II population. Population genetic analyses of single nucleotide polymorphisms indicate variation between closely related strains is not maintained by positive selection, suggesting that these regions do not represent adaptive differences between strains. Thus, the most likely explanation for the observed patterns of polymorphism is divergence of ancestral strains due to geographic isolation, followed by mixing and subsequent recombination.
Douglas E. Rawlings - One of the best experts on this subject based on the ideXlab platform.
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Resistance determinants of a highly arsenic-resistant strain of Leptospirillum ferriphilum isolated from a commercial biooxidation tank.
Applied and environmental microbiology, 2006Co-Authors: I. Marla Tuffin, Stanton Bevan Ernest Hector, Shelly M. Deane, Douglas E. RawlingsAbstract:Two sets of arsenic resistance genes were isolated from the highly arsenic-resistant Leptospirillum ferriphilum Fairview strain. One set is located on a transposon, TnLfArs, and is related to the previously identified TnAtcArs from Acidithiobacillus caldus isolated from the same arsenopyrite biooxidation tank as L. ferriphilum. TnLfArs conferred resistance to arsenite and arsenate and was transpositionally active in Escherichia coli. TnLfArs and TnAtcArs were sufficiently different for them not to have been transferred from one type of bacterium to the other in the biooxidation tank. The second set of arsenic resistance genes conferred very low levels of resistance in E. coli and appeared to be poorly expressed in both L. ferriphilum and E. coli.
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Isolation, Sequence Analysis, and Comparison of Two Plasmids (28 and 29 Kilobases) from the Biomining Bacterium Leptospirillum ferrooxidans ATCC 49879
Applied and environmental microbiology, 2005Co-Authors: Nicolette J. Coram, Leonardo Joaquim Van Zyl, Douglas E. RawlingsAbstract:Two plasmids, of 28,878 bp and 28,012 bp, were isolated from Leptospirillum ferrooxidans ATCC 49879. Altogether, a total of 67 open reading frames (ORFs) were identified on both plasmids, of which 32 had predicted products with high homology to proteins of known function, while 11 ORFs had predicted products with homology to previously identified proteins of unknown function. Twenty-four ORFs had products with no homologues in the GenBank/NCBI database. An analysis of the ORFs and other features of the two plasmids, the first to be isolated from a bacterium of the genus Leptospirillum, is presented.
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Molecular relationship between two groups of the genus Leptospirillum and the finding that Leptospirillum ferriphilum sp. nov. Dominates south African commercial biooxidation tanks that operate at 40°C
Applied and environmental microbiology, 2002Co-Authors: Nicolette J. Coram, Douglas E. RawlingsAbstract:Iron-oxidizing bacteria belonging to the genus Leptospirillum are of great importance in continuous-flow commercial biooxidation reactors, used for extracting metals from minerals, that operate at 40°C or less. They also form part of the microbial community responsible for the generation of acid mine drainage. More than 16 isolates of leptospirilla were included in this study, and they were clearly divisible into two major groups. Group I leptospirilla had G+C moles percent ratios within the range 49 to 52% and had three copies of rrn genes, and based on 16S rRNA sequence data, these isolates clustered together with the Leptospirillum ferrooxidans type strain (DSM2705 or L15). Group II leptospirilla had G+C moles percent ratios of 55 to 58% and had two copies of rrn genes, and based on 16S rRNA sequence data, they form a separate cluster. Genome DNA-DNA hybridization experiments indicated that three similarity subgroups were present among the leptospirilla tested, with two DNA-DNA hybridization similarity subgroups found within group I. The two groups could also be distinguished based on the sizes of their 16S-23S rRNA gene spacer regions. We propose that the group II leptospirilla should be recognized as a separate species with the name Leptospirillum ferriphilum sp. nov. Members of the two species can be rapidly distinguished from each other by amplification of their 16S rRNA genes and by carrying out restriction enzyme digests of the products. Several, but not all, isolates of the group II leptospirilla, but none from group I (L. ferrooxidans), were capable of growth at 45°C. All the leptospirilla isolated from commercial biooxidation tanks in South Africa were from group II.
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Thiobacillus caldus and Leptospirillum ferrooxidans are widely distributed in continuous flow biooxidation tanks used to treat a variety of metal containing ores and concentrates
Biohydrometallurgy and the Environment Toward the Mining of the 21st Century - Proceedings of the International Biohydrometallurgy Symposium, 1999Co-Authors: Douglas E. Rawlings, N.j. Coram, Murray N. Gardner, Shelly M. DeaneAbstract:Using 16S rDNA-based techniques, several workers have reported that Leptospirillum ferrooxidans and Thiobacillus thiooxidans are the bacteria most commonly encountered in biooxidation processes for the treatment of copper by heap leaching as well as the treatment of zinc-lead or arsenopyrite concentrates by continuous-flow tank leaching. We have compared the 16S rRNA genes from four strains of Thiobacillus caldus and identified two restriction enzymes which permit the 16S rDNA from T. caldus to be distinguished from closely related strains of T. thiooxidans . DNA has been isolated directly from continuous-flow biooxidation tanks treating copper, nickel or arsenopyrite concentrates at 40–55 °.By examining the restriction enzyme patterns of the amplified 16S rDNA, we report that even at 40 °C it is the moderate thermophile T. caldus , rather than T. thiooxidans , which is the dominant sulphur-oxidising bacterium in these tanks. By examining the restriction enzyme patterns of the 16S rDNA from fifteen strains of Leptospirillum spp isolated from different parts of the world, we have confirmed that the leptospirilli can be divided into two major groups. Furthermore, we have found that the leptospirilli which dominate the iron-oxidising bacteria in the continuous-flow biooxidation tanks belong to the same sub-group as the L. ferrooxidans type strain (DSM2705).Restriction enzyme maps of the 16S rDNA which enable isolates of T. ferrooxidans, T. thiooxidans, T. caldus and the subgroups of the genus Leptospirillum to be readily distinguished from each other are presented.
Víctor Parro - One of the best experts on this subject based on the ideXlab platform.
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Comparative genomic analysis reveals novel facts about Leptospirillum spp. cytochromes.
Journal of molecular microbiology and biotechnology, 2012Co-Authors: Gloria Levicán, Omar Orellana, Mercedes Moreno-paz, Manuel J. Gómez, Renato Chávez, Víctor ParroAbstract:Chemolithoautotrophic acidophilic bacteria, which belong to the genus Leptospirillum , can only grow with Fe(II) as electron donor and oxygen as an electron acceptor. Members of this
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Differential Gene Expression of Industrial Bioleaching Transcriptomes by Leptospirillum Ferrooxidans DNA Microarray
Advanced Materials Research, 2009Co-Authors: Francisco Remonsellez, Mercedes Moreno-paz, Víctor Parro, Cecilia DemergassoAbstract:Heap bioleaching is presently the most successful technology for copper extraction from low-grade sulfide ores. Metabolic behaviors and adaptation mechanisms of microbial communities to this system remain unknown. A combination of molecular approaches has been used to determine the key microorganisms in the Escondida Sulphide Heap. This work reports the global gene expression in industrial bioleaching samples by using a specific DNA microarray of Leptospirillum ferrooxidans to better understand the metabolic functions displayed by Leptospirillum spp. iron oxidizers as mineral leaching proceeds. Quantitative real-time PCR analysis showed low cell numbers of Leptospirillum species during the first part of the irrigation period, however, it became the most abundant and active in the second part of the cycle. Transcriptome analysis by DNA microarray could provide specifics transcription patterns in the different stages of the industrial process. We studied the gene expression from bioleaching heap samples with variable Leptospirillum cell numbers, operation times and with different chemical and physical conditions. The results showed induction of genes involved in energetic metabolism, electron transport, ribosomal proteins, DNA repair and response to heavy metals when Leptospirillum species were most abundant and active. We suggest that up- and down-regulation of specifics genes could be used as indicators of physiological responses to operational conditions in the bioleaching systems.
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Evaluation of Leptospirillum spp. in the Río Tinto, a model of interest to biohydrometallurgy
Hydrometallurgy, 2008Co-Authors: Antonio García-moyano, Mercedes Moreno-paz, Víctor Parro, Elena González-toril, Ricardo AmilsAbstract:ARTICLE I NFO Members of the Leptospirillum genus have recently been found to be not only the most representative prokaryotes in the Rio Tinto, a natural extreme acidic habitat, but also in other acidic environments (AMD), as well as in biohydrometallurgical operations. The main objective of this work was to better understand and control industrial biohydrometallurgical processes by studying the role of chemolithoautotrophic bacteria of this genus in the Tinto ecosystem. Different strains of Leptospirillum were isolated from the Tinto basin and physiologically and genetically characterized by Pulsed Field Gel Electrophoresis (PFGE) and DNA microarrays. Certain metabolic capabilities, such as iron oxidation, pyrite leaching and nitrogen fixation, were determined for each strain. Complementary molecular ecology techniques (fluorescence in situ hybridization (FISH and CARD-FISH) and 16S rRNA gene cloning) were used to study the microbial diversity and the distribution of leptospirilli along the iron gradient of the Tinto ecosystem.
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Microbial Ecology of Leptospirillum spp. in Río Tinto, a Model of Interest to Biohydrometallurgy
Advanced Materials Research, 2007Co-Authors: Antonio García-moyano, Mercedes Moreno-paz, Víctor Parro, Elena González-toril, Ricardo AmilsAbstract:Members of Leptospirillum genus have emerged not only as one of the most representative bacteria in the Rio Tinto ecosystem, but also in other acidic environments (AMD), and in biohydrometallurgical operations. The main objective of this work was to study the role of chemolithoautotrophic bacteria of the genus Leptospirillum in the Rio Tinto iron cycle (an extreme acidic environment, characterized by its constant low pH) to better understand and control industrial biohydrometallurgical processes. Different strains of Leptospirillum were isolated from the Rio Tinto basin and physiologically and genetically characterized. Certain metabolic capabilities, such as pyrite leaching, iron oxidation and nitrogen fixation, were determined for each strain. Complementary molecular ecology techniques (FISH, CARD-FISH and cloning) were used to study the microbial diversity and the distribution of leptospirilli along the iron gradient in the different phases of Rio Tinto: water column, anaerobic sediments and biofilms.
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Nitrogen fixation in acidophile iron-oxidizing bacteria: the nif regulon of Leptospirillum ferrooxidans.
Research in microbiology, 2004Co-Authors: Víctor Parro, Mercedes Moreno-pazAbstract:The Gram-negative iron-oxidizing bacterium Leptospirillum ferrooxidans contains all genes necessary for nitrogen fixation, from genes encoding the Mo-Fe nitrogenase, the specific regulator (nifA), global regulators like glnB and ntrC like genes, to other sensors and transport systems somehow related to nitrogen assimilation. We review current knowledge about the nif regulon and its connection with other metabolic functions in L. ferrooxidans.