Examinando por Autor "Quatrini, R."
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Ítem Comparative Genomics Analysis of a New Exiguobacterium Strain from Salar de Huasco Reveals a Repertoire of Stress-Related Genes and Arsenic Resistance(FRONTIERS MEDIA, 2017-03) Castro-Severyn, J.; Remonsellez, F.; Valenzuela, S.L.; Salinas, C.; Fortt, J.; Aguilar, P.; Pardo-Esté, C.; Dorador, C.; Quatrini, R.; Molina, F.; Aguayo, D.; Castro-Nallar, E.; Saavedra, C.P.The Atacama Desert hosts diverse ecosystems including salt flats and shallow Andean lakes. Several heavy metals are found in the Atacama Desert, and microorganisms growing in this environment show varying levels of resistance/tolerance to copper, tellurium, and arsenic, among others. Herein, we report the genome sequence and comparative genomic analysis of a new Exiguobacterium strain, sp. SH31, isolated from an altiplanic shallow athalassohaline lake. Exiguobacterium sp. SH31 belongs to the phylogenetic Group II and its closest relative is Exiguobacterium sp. S17, isolated from the Argentinian Altiplano (95% average nucleotide identity). Strain SH31 encodes a wide repertoire of proteins required for cadmium, copper, mercury, tellurium, chromium, and arsenic resistance. Of the 34 Exiguobacterium genomes that were inspected, only isolates SH31 and S17 encode the arsenic efflux pump Acr3. Strain SH31 was able to grow in up to 10 mM arsenite and 100 mM arsenate, indicating that it is arsenic resistant. Further, expression of the ars operon and acr3 was strongly induced in response to both toxics, suggesting that the arsenic efflux pump Acr3 mediates arsenic resistance in Exiguobacterium sp. SH31.Ítem DNA, cell wall and general oxidative damage underlie the tellurite/cefotaxime synergistic effect in Escherichia coli(Public Library of Science, 2013-11) Molina-Quiroz, R.; Loyola, D.; Muñoz-Villagrán, C.; Quatrini, R.; Vásquez, C.; Pérez-Donoso, J.The constant emergence of antibiotic multi-resistant pathogens is a concern worldwide. An alternative for bacterial treatment using nM concentrations of tellurite was recently proposed to boost antibiotic-toxicity and a synergistic effect of tellurite/cefotaxime (CTX) was described. In this work, the molecular mechanism underlying this phenomenon is proposed. Global changes of the transcriptional profile of Escherichia coli exposed to tellurite/CTX were determined by DNA microarrays. Induction of a number of stress regulators (as SoxS), genes related to oxidative damage and membrane transporters was observed. Accordingly, increased tellurite adsorption/uptake and oxidative injuries to proteins and DNA were determined in cells exposed to the mixture of toxicants, suggesting that the tellurite-mediated CTX-potentiating effect is dependent, at least in part, on oxidative stress. Thus, the synergistic tellurite-mediated CTX-potentiating effect depends on increased tellurite uptake/adsorption which results in damage to proteins, DNA and probably other macromolecules. Our findings represent a contribution to the current knowledge of bacterial physiology under antibiotic stress and can be of great interest in the development of new antibiotic-potentiating strategies.Ítem Draft genome sequence of Acidithiobacillus thiooxidans CLST isolated from the acidic hypersaline Gorbea salt flat in northern Chile(BioMed Central, 2017-12) Quatrini, R.; Escudero, L.V.; Moya-Beltrán, A.; Galleguillos, P.A.; Issotta, F.; Acosta, M.; Cárdenas, J.P.; Nuñez, H.; Salinas, K.; Holmes, D.S.; Demergasso, C.Acidithiobacillus thiooxidansCLST is an extremely acidophilic gamma-proteobacteria that was isolated from the Gorbea salt flat, an acidic hypersaline environment in northern Chile. This kind of environment is considered a terrestrial analog of ancient Martian terrains and a source of new material for biotechnological applications. A. thiooxidansplays a key role in industrial bioleaching; it has the capacity of generating and maintaining acidic conditions by producing sulfuric acid and it can also remove sulfur layers from the surface of minerals, which are detrimental for their dissolution. CLST is a strain of A. thiooxidansable to tolerate moderate chloride concentrations (up to 15 g L-1 Cl-), a feature that is quite unusual in extreme acidophilic microorganisms. Basic microbiological features and genomic properties of this biotechnologically relevant strain are described in this work. The 3,974,949 bp draft genome is arranged into 40 scaffolds of 389 contigs containing 3866 protein-coding genes and 75 RNAs encoding genes. This is the first draft genome of a halotolerant A. thiooxidansstrain. The release of the genome sequence of this strain improves representation of these extreme acidophilic Gram negative bacteria in public databases and strengthens the framework for further investigation of the physiological diversity and ecological function of A. thiooxidans populations.Ítem Draft genome sequence of the type strain of the sulfur-oxidizing acidophile, Acidithiobacillus albertensis (DSM 14366)(BioMed Central, 2017-12) Castro, M.; Moya-Beltrán, A.; Covarrubias, P.C.; Gonzalez, M.; Cardenas, J.P.; Issotta, F.; Nuñez, H.; Acuña, L.G.; Encina, G.; Holmes, D.S.; Johnson, D.B.; Quatrini, R.Acidithiobacillus albertensis is an extremely acidophilic, mesophilic, obligatory autotrophic sulfur-oxidizer, with potential importance in the bioleaching of sulfidic metal ores, first described in the 1980s. Here we present the draft genome sequence of Acidithiobacillus albertensis DSM 14366T, thereby both filling a long-standing gap in the genomics of the acidithiobacilli, and providing further insight into the understanding of the biology of the non iron-oxidizing members of the Acidithiobacillus genus. The assembled genome is 3,1 Mb, and contains 47 tRNAs, tmRNA gene and 2 rRNA operons, along with 3149 protein-coding predicted genes. The Whole Genome Shotgun project was deposited in DDBJ/EMBL/GenBank under the accessionÍtem Microbial iron management mechanisms in extremely acidic environments: Comparative genomics evidence for diversity and versatility(BioMed Central, 2008-11) Osorio, H.; Martínez, V.; Nieto, P.A.; Holmes, D.S.; Quatrini, R.Background. Iron is an essential nutrient but can be toxic at high intracellular concentrations and organisms have evolved tightly regulated mechanisms for iron uptake and homeostasis. Information on iron management mechanisms is available for organisms living at circumneutral pH. However, very little is known about how acidophilic bacteria, especially those used for industrial copper bioleaching, cope with environmental iron loads that can be 1018 times the concentration found in pH neutral environments. This study was motivated by the need to fill this lacuna in knowledge. An understanding of how microorganisms thrive in acidic ecosystems with high iron loads requires a comprehensive investigation of the strategies to acquire iron and to coordinate this acquisition with utilization, storage and oxidation of iron through metal responsive regulation. In silico prediction of iron management genes and Fur regulation was carried out for three Acidithiobacilli: Acidithiobacillus ferrooxidans (iron and sulfur oxidizer) A. thiooxidans and A. caldus (sulfur oxidizers) that can live between pH 1 and pH 5 and for three strict iron oxidizers of the Leptospirillum genus that live at pH 1 or below. Results. Acidithiobacilli have predicted FeoB-like Fe(II) and Nramp-like Fe(II)-Mn(II) transporters. They also have 14 different TonB dependent ferri-siderophore transporters of diverse siderophore affinity, although they do not produce classical siderophores. Instead they have predicted novel mechanisms for dicitrate synthesis and possibly also for phosphate-chelation mediated iron uptake. It is hypothesized that the unexpectedly large number and diversity of Fe(III)-uptake systems confers versatility to this group of acidophiles, especially in higher pH environments (pH 4-5) where soluble iron may not be abundant. In contrast, Leptospirilla have only a FtrI-Fet3P-like permease and three TonB dependent ferri-dicitrate siderophore systems. This paucity of iron uptake systems could reflect their obligatory occupation of extremely low pH environments where high concentrations of soluble iron may always be available and were oxidized sulfur species might not compromise iron speciation dynamics. Presence of bacterioferritin in the Acidithiobacilli, polyphosphate accumulation functions and variants of FieF-like diffusion facilitators in both Acidithiobacilli and Leptospirilla, indicate that they may remove or store iron under conditions of variable availability. In addition, the Fe(II)-oxidizing capacity of both A. ferrooxidans and Leptospirilla could itself be a way to evade iron stress imposed by readily available Fe(II) ions at low pH. Fur regulatory sites have been predicted for a number of gene clusters including iron related and non-iron related functions in both the Acidithiobacilli and Leptospirilla, laying the foundation for the future discovery of iron regulated and iron-phosphate coordinated regulatory control circuits. Conclusion. In silico analyses of the genomes of acidophilic bacteria are beginning to tease apart the mechanisms that mediate iron uptake and homeostasis in low pH environments. Initial models pinpoint significant differences in abundance and diversity of iron management mechanisms between Leptospirilla and Acidithiobacilli, and begin to reveal how these two groups respond to iron cycling and iron fluctuations in naturally acidic environments and in industrial operations. Niche partitions and ecological successions between acidophilic microorganisms may be partially explained by these observed differences. Models derived from these analyses pave the way for improved hypothesis testing and well directed experimental investigation. In addition, aspects of these models should challenge investigators to evaluate alternative iron management strategies in non-acidophilic model organisms. © 2008 Osorio et al; licensee BioMed Central Ltd.Ítem The ferric iron uptake regulator (Fur) from the extreme acidophile Acidithiobacillus ferrooxidans(Microbiology Society, 2005-06) Quatrini, R.; Lefimil, C.; Holmes, D.; Jedlicki, E.Acidithiobacillus ferrooxidans is a Gram-negative bacterium that lives at pH 2 in high concentrations of soluble ferrous and ferric iron, making it an interesting model for understanding the biological mechanisms of bacterial iron uptake and homeostasis in extremely acid conditions. A candidate furAF (Ferric Uptake Regulator) gene was identified in the A. ferrooxidans ATCC 23270 genome. FurAF has significant sequence similarity, including conservation of functional motifs, to known Fur orthologues and exhibits cross-reactivity to Escherichia coli Fur antiserum. The furAF gene is able to complement fur deficiency in E. coli in an iron-responsive manner. FurAF is also able to bind specifically to E. coli Fur regulatory regions (Fur boxes) and to a candidate Fur box from A. ferrooxidans, as judged by electrophoretic mobility shift assays. FurAF represses gene expression from E. coli Fur-responsive promoters fiu and fhuF when expressed at high protein levels. However, it increases gene expression from these promoters at low concentrations and possibly from other Fur-regulated promoters involved in iron-responsive oxidative stress respon.