Arsenic Nanoparticles Trigger Apoptosis via Induction in OECM-1 Cells.

Arsenic compounds have been used as therapeutic alternatives for several diseases including cancer. In the following work, we obtained arsenic nanoparticles (AsNPs) produced by an anaerobic bacterium from the , in northern Chile, and evaluated their effects on the human oral squamous carcinoma cell line OECM-1. Resazurin reduction assays were carried out on these cells using 1-100 µM of AsNPs, finding a concentration-dependent reduction in cell viability that was not observed for the non-tumoral gastric mucosa-derived cell line GES-1.

Corrigendum: Hyperarid soil microbial community response to simulated rainfall.

[This corrects the article DOI: 10.3389/fmicb.2023.

The dynamics of two iron-oxidizing Acidithiobacillus strains in industrial copper sulfide heap-leaching.

Several species within the Acidithiobacillus (At.) genus can derive energy from oxidizing ferrous iron and sulfur. Two bacterial strains according to their 16S rRNA gene sequences closely related to At.

Hyperarid soil microbial community response to simulated rainfall.

The exceptionally long and protracted aridity in the Atacama Desert (AD), Chile, provides an extreme, terrestrial ecosystem that is ideal for studying microbial community dynamics under hyperarid conditions. Our aim was to characterize the temporal response of hyperarid soil AD microbial communities to simulated rainfall (5% g water/g dry soil for 4 weeks) without nutrient amendment. We conducted replicated microcosm experiments with surface soils from two previously well-characterized AD hyperarid locations near Yungay at 1242 and 1609 masl (YUN1242 and YUN1609) with distinct microbial community compositions and average soil relative humidity levels of 21 and 17%, respectively.

Looking for the mechanism of arsenate respiration of sp. strain 3D3, independent of ArrAB.

The literature has reported the isolation of arsenate-dependent growing microorganisms which lack a canonical homolog for respiratory arsenate reductase, ArrAB. We recently isolated an arsenate-dependent growing bacterium from volcanic arsenic-bearing environments in Northern Chile, sp. strain 3D3 () and studied the arsenic metabolism in this Gram-positive isolate.

Physical, chemical, and microbial feedbacks controlling brine geochemistry and lake morphology in polyextreme salar environments.

Despite the harsh environmental conditions in the world's oldest and driest desert, some salt flat or 'salar' environments in the Atacama Desert host standing bodies of water known as saline lakes. Evaporite minerals deposited within saline lakes result from the equilibrium of environmental, sedimentological, and biogeochemical processes that occur in the salar; consequently, these minerals are sensitive records of human activities and ecological, evolutionary, and geological changes. The objective of this study was to evaluate feedbacks between physical, chemical, and microbial processes that culminate in distinct trends in brine chemistry, saline lake morphology, and associated evaporite sediments.

From Laboratory towards Industrial Operation: Biomarkers for Acidophilic Metabolic Activity in Bioleaching Systems.

In the actual mining scenario, copper bioleaching, mainly raw mined material known as run-of-mine (ROM) copper bioleaching, is the best alternative for the treatment of marginal resources that are not currently considered part of the profitable reserves because of the cost associated with leading technologies in copper extraction. It is foreseen that bioleaching will play a complementary role in either concentration-as it does in Minera Escondida Ltd. (MEL)-or chloride main leaching plants.

An indigenous bacterium with enhanced performance of microbially-induced Ca-carbonate biomineralization under extreme alkaline conditions for concrete and soil-improvement industries.

The advantages of microbial induced carbonate mineralization for soil-stabilization and building-material industries are under extensive investigation. The pH is one of the influential parameters on the desired calcium carbonate mineralization due to the resulting textures of this mineral. Moreover, the decrease in microbial growth under the extreme alkaline environment compatible with the sustainability of concrete has been the bottleneck for an effective application of Microbial Induced Carbonate Precipitation (MICP) in the concrete industry.

Validation of Genetic Markers Associated to Oxygen Availability in Low-Grade Copper Bioleaching Systems: An Industrial Application.

Forced aeration is one of the major energy consumption factors of the bioleaching process of run-of-mine ore. The effect of aeration in the microbial community has scarcely been studied at industrial level. is one of the most representative species of the Fe producing population in this kind of systems.

Microbiology and Nitrogen Cycle in the Benthic Sediments of a Glacial Oligotrophic Deep Andean Lake as Analog of Ancient Martian Lake-Beds.

Potential benthic habitats of early Mars lakes, probably oligotrophic, could range from hydrothermal to cold sediments. Dynamic processes in the water column (such as turbidity or UV penetration) as well as in the benthic bed (temperature gradients, turbation, or sedimentation rate) contribute to supply nutrients to a potential microbial ecosystem. High altitude, oligotrophic, and deep Andean lakes with active deglaciation processes and recent or past volcanic activity are natural models to assess the feasibility of life in other planetary lake/ocean environments and to develop technology for their exploration.

Identification of trehalose as a compatible solute in different species of acidophilic bacteria.

The major industrial heap bioleaching processes are located in desert regions (mainly Chile and Australia) where fresh water is scarce and the use of resources with low water activity becomes an attractive alternative. However, in spite of the importance of the microbial populations involved in these processes, little is known about their response or adaptation to osmotic stress. In order to investigate the response to osmotic stress in these microorganisms, six species of acidophilic bacteria were grown at elevated osmotic strength in liquid media, and the compatible solutes synthesised were identified using ion chromatography and MALDI-TOF mass spectrometry.

Correction to: A thiotrophic microbial community in an acidic brine lake in Northern Chile.

In Table 1 of the original article, the unit mg/L was incorrectly published as ng/L in the aluminum, chloride, sulphate and OM columns.

A thiotrophic microbial community in an acidic brine lake in Northern Chile.

The endorheic basins of the Northern Chilean Altiplano contain saline lakes and salt flats. Two of the salt flats, Gorbea and Ignorado, have high acidic brines. The causes of the local acidity have been attributed to the occurrence of volcanic native sulfur, the release of sulfuric acid by oxidation, and the low buffering capacity of the rocks in the area.

Watershed-Induced Limnological and Microbial Status in Two Oligotrophic Andean Lakes Exposed to the Same Climatic Scenario.

Laguna Negra and Lo Encañado are two oligotrophic Andean lakes forming part of the system fed by meltwater from distinct glacial tongues of the Echaurren glacier in central Chile, which is in a recession period. The recent increase in temperature and decline in precipitation have led to an increase of glacial meltwater and sediments entering these lakes. Although the lacustrine systems are also hydrogeologically connected, the limnology of the lakes is strongly controlled by the surface processes related to the respective sub-watersheds and hydrology.

Draft genome sequence of CLST isolated from the acidic hypersaline Gorbea salt flat in northern Chile.

10.1601/nm.2199 CLST is an extremely acidophilic gamma-proteobacteria that was isolated from the Gorbea salt flat, an acidic hypersaline environment in northern Chile.

Microbial Community Structure and the Persistence of Cyanobacterial Populations in Salt Crusts of the Hyperarid Atacama Desert from Genome-Resolved Metagenomics.

Although once thought to be devoid of biology, recent studies have identified salt deposits as oases for life in the hyperarid Atacama Desert. To examine spatial patterns of microbial species and key nutrient sources, we genomically characterized 26 salt crusts from three sites along a fog gradient. The communities are dominated by a large variety of Halobacteriales and Bacteroidetes, plus a few algal and Cyanobacterial species.

First draft genome sequence of a strain from the genus isolated from Salar de Ascotán in Northern Chile.

sp 3D3 (ATCC BAA-2418) is an arsenate-reducing halotolerant strain within the phylum, isolated from the Salar de Ascotán, a hypersaline salt flat in Northern Chile. This high-Andean closed basin is an athalassohaline environment located at the bottom of a tectonic basin surrounded by mountain range, including some active volcanoes. This landscape can be an advantageous system to explore the effect of salinity on microorganisms that mediate biogeochemical reactions.

The Ecological Coherence of Temperature and Salinity Tolerance Interaction and Pigmentation in a Non-marine Isolated from Salar de Atacama.

The occurrence of microorganisms from the genus in saline lakes from northern Chile had been evidenced using Numerical Taxonomy decades before and, more recently, by phylogenetic analyses of environmental samples and isolates. Most of the knowledge about this genus came from marine isolates and showed temperature and salinity to be integral agents in shaping the niche of the populations. The stress tolerance phenotypes of sp.

Biomarkers and Metabolic Patterns in the Sediments of Evolving Glacial Lakes as a Proxy for Planetary Lake Exploration.

Oligotrophic glacial lakes in the Andes Mountains serve as models to study the effects of climate change on natural biological systems. The persistent high UV regime and evolution of the lake biota due to deglaciation make Andean lake ecosystems potential analogues in the search for life on other planetary bodies. Our objective was to identify microbial biomarkers and metabolic patterns that represent time points in the evolutionary history of Andean glacial lakes, as these may be used in long-term studies as microscale indicators of climate change processes.

Draft genome sequence of chloride-tolerant Leptospirillum ferriphilum Sp-Cl from industrial bioleaching operations in northern Chile.

Leptospirillum ferriphilum Sp-Cl is a Gram negative, thermotolerant, curved, rod-shaped bacterium, isolated from an industrial bioleaching operation in northern Chile, where chalcocite is the major copper mineral and copper hydroxychloride atacamite is present in variable proportions in the ore. This strain has unique features as compared to the other members of the species, namely resistance to elevated concentrations of chloride, sulfate and metals. Basic microbiological features and genomic properties of this biotechnologically relevant strain are described in this work.

Draft Genome Sequence of Nitrincola sp. Strain A-D6, an Arsenic-Resistant Gammaproteobacterium Isolated from a Salt Flat.

We report Nitrincola sp. strain A-D6, which was characterized as an arsenic-resistant bacterium isolated from the Ascotán Salt Flat in northern Chile. The size of the genome is 3,795,776 bp, with a G+C content of 49.

Distribution of microbial arsenic reduction, oxidation and extrusion genes along a wide range of environmental arsenic concentrations.

The presence of the arsenic oxidation, reduction, and extrusion genes arsC, arrA, aioA, and acr3 was explored in a range of natural environments in northern Chile, with arsenic concentrations spanning six orders of magnitude. A combination of primers from the literature and newly designed primers were used to explore the presence of the arsC gene, coding for the reduction of As (V) to As (III) in one of the most common detoxification mechanisms. Enterobacterial related arsC genes appeared only in the environments with the lowest As concentration, while Firmicutes-like genes were present throughout the range of As concentrations.

AHL signaling molecules with a large acyl chain enhance biofilm formation on sulfur and metal sulfides by the bioleaching bacterium Acidithiobacillus ferrooxidans.

Biofilm formation plays a pivotal role in bioleaching activities of bacteria in both industrial and natural environments. Here, by visualizing attached bacterial cells on energetic substrates with different microscopy techniques, we obtained the first direct evidence that it is possible to positively modulate biofilm formation of the extremophilic bacterium Acidithiobacillus ferrooxidans on sulfur and pyrite surfaces by using Quorum Sensing molecules of the N-acylhomoserine lactone type (AHLs). Our results revealed that AHL-signaling molecules with a long acyl chain (12 or 14 carbons) increased the adhesion of A.

Enrichment of arsenic transforming and resistant heterotrophic bacteria from sediments of two salt lakes in Northern Chile.

Microbial populations are involved in the arsenic biogeochemical cycle in catalyzing arsenic transformations and playing indirect roles. To investigate which ecotypes among the diverse microbial communities could have a role in cycling arsenic in salt lakes in Northern Chile and to obtain clues to facilitate their isolation in pure culture, sediment samples from Salar de Ascotán and Salar de Atacama were cultured in diluted LB medium amended with NaCl and arsenic, at different incubation conditions. The samples and the cultures were analyzed by nucleic acid extraction, fingerprinting analysis, and sequencing.