RESUMEN
AIM: To assess the effectiveness of Bacillus subtilis strain LN8B as a biocollector for recovering pyrite (Py) and chalcopyrite (CPy) in both seawater (Sw) and deionized water (Dw), and to explore the underlying adhesion mechanism in these bioflotation experiments. MATERIALS AND METHODS: The bioflotation test utilized B. subtilis strain LN8B as the biocollector through microflotation experiments. Additionally, frother methyl isobutyl carbinol (MIBC) and conventional collector potassium amyl xanthate (PAX) were introduced in some experiments. The zeta potential (ZP) and Fourier-transform infrared spectroscopy (FTIR) was employed to explore the adhesion mechanism of Py and CPy interacting with the biocollector in Sw and Dw. The adaptability of the B. subtilis strain to different water types and salinities was assessed through growth curves measuring optical density. Finally, antibiotic susceptibility tests were conducted to evaluate potential risks of the biocollector. RESULTS: Superior outcomes were observed in Sw where Py and CPy recovery was â¼39.3% ± 7.7% and 41.1% ± 5.8%, respectively, without microorganisms' presence. However, B. subtilis LN8B potentiate Py and CPy recovery, reaching 72.8% ± 4.9% and 84.6% ± 1.5%, respectively. When MIBC was added, only the Py recovery was improved (89.4% ± 3.6%), depicting an adverse effect for CPy (81.8% ± 1.1%). ZP measurements indicated increased mineral surface hydrophobicity when Py and CPy interacted with the biocollector in both Sw and Dw. FTIR revealed the presence of protein-related amide peaks, highlighting the hydrophobic nature of the bacterium. The adaptability of this strain to diverse water types and salinities was assessed, demonstrating remarkable growth versatility. Antibiotic susceptibility tests indicated that B. subtilis LN8B was susceptible to 23 of the 25 antibiotics examined, suggesting it poses minimal environmental risks. CONCLUSIONS: The study substantiates the biotechnological promise of B. subtilis strain LN8B as an efficient sulfide collector for promoting cleaner mineral production. This effectiveness is attributed to its ability to induce mineral surface hydrophobicity, a result of the distinct characteristics of proteins within its cell wall.
Asunto(s)
Bacillus subtilis , Cobre , Hierro , Minerales , Bacillus subtilis/metabolismo , Agua de Mar , Sulfuros/farmacología , Sulfuros/metabolismo , Agua/metabolismo , Antibacterianos/farmacología , Antibacterianos/metabolismoRESUMEN
Cyanobacteria produce exopolysaccharides (EPSs) as an adaptative mechanism against ultraviolet radiation and desiccation. Cellulose is present in the extracellular polymeric substance in some cyanobacteria genera and it has been proposed as a raw material for biofuel production. The goal of this work was to evaluate the cellulose presence in EPS of Atacama cyanobacteria strains and its use as an alternative and innovative biological source to produce bioethanol. The presence of cellulose was evaluated using techniques of molecular biology, bioinformatics, and electronic microscopy. The conserved motif D,D,D,35QXXRW, characteristic of processive ß-glycosyltransferase in all cellulose-producing organisms, was identified in the genome of the LLA-10 strain. This is evidence that cellulose synthase in the LLA-10 strain is a functional enzyme. EPS from Atacama cyanobacteria was hydrolyzed by ß-glucosidases (cellobiase and cellulase) and the released glucose was yeast-fermented to ethanol. Ethanol production reached 172.69 ± 0.02 mg ethanol/g EPS after 48 h of incubation. These results are the first step in the evaluation of EPS produced by native cyanobacteria isolated from northern Chile for future biotechnological applications such as the production of bioethanol.
RESUMEN
The dispersion of microorganisms through the atmosphere is a continual and essential process that underpins biogeography and ecosystem development and function. Despite the ubiquity of atmospheric microorganisms globally, specific knowledge of the determinants of atmospheric microbial diversity at any given location remains unresolved. Here we describe bacterial diversity in the atmospheric boundary layer and underlying soil at twelve globally distributed locations encompassing all major biomes, and characterise the contribution of local and distant soils to the observed atmospheric community. Across biomes the diversity of bacteria in the atmosphere was negatively correlated with mean annual precipitation but positively correlated to mean annual temperature. We identified distinct non-randomly assembled atmosphere and soil communities from each location, and some broad trends persisted across biomes including the enrichment of desiccation and UV tolerant taxa in the atmospheric community. Source tracking revealed that local soils were more influential than distant soil sources in determining observed diversity in the atmosphere, with more emissive semi-arid and arid biomes contributing most to signatures from distant soil. Our findings highlight complexities in the atmospheric microbiota that are relevant to understanding regional and global ecosystem connectivity.
Asunto(s)
Ecosistema , Microbiota , Suelo , Bacterias , Atmósfera , Temperatura , Microbiología del SueloRESUMEN
Substantial knowledge has accumulated on the microbiome of the hyperarid Atacama Desert during the last two decades; however, information on Atacama free-living amoebae (FLA) is limited and increasing efforts are required. FLA are polyphyletic heterotrophic naked or testate protists that feed on organic matter, fungi, protozoa, and bacteria and may disseminate infections. Amoebae in Chile are represented by 416 taxa and 64 genera, and 29 taxa have been identified in arid shrub lands at the southern limit of the Atacama Desert, and Acanthamoeba are present in all the country's regions. To expand our knowledge and to contribute to the biogeographic distribution of Atacama FLA, we report the dominant presence of members of the genus Acanthamoeba in water and sediment sampled at the Loa and Salado rivers in the pre-Andean zone of the Antofagasta Region, northern Chile, at sites 2500 m above sea level. We expect these observations and preliminary evidence of FLA presence in other wetlands (Chiuchiu, Tebenquiche) in this region to be incentive for further exploration of Atacama amoebae.
RESUMEN
Cyanobacterial macrocolonies known as Llayta are found in Andean wetlands and have been consumed since pre-Columbian times in South America. Macrocolonies of filamentous cyanobacteria are niches for colonization by other microorganisms. However, the microbiome of edible Llayta has not been explored. Based on a culture-independent approach, we report the presence, identification, and metagenomic genome reconstruction of Cyanocohniella sp. LLY associated to Llayta trichomes. The assembled genome of strain LLY is now available for further inquiries and may be instrumental for taxonomic advances concerning this genus. All known members of the Cyanocohniella genus have been isolated from salty European habitats. A biogeographic gap for the Cyanocohniella genus is partially filled by the existence of strain LLY in Andes Mountains wetlands in South America as a new habitat. This is the first genome available for members of this genus. Genes involved in primary and secondary metabolism are described, providing new insights regarding the putative metabolic capabilities of Cyanocohniella sp. LLY.
RESUMEN
During mating, males provide not only the spermatozoa to fertilize the oocyte but also other stimuli that are essential for initiating and maintaining the reproductive programme in females. In the mammalian oviduct, mating regulates sperm storage, egg transport, fertilization, early embryonic development, and oestradiol metabolism. However, the main molecules underlying these processes are poorly understood. Using microarray analyses, we identified 58 genes that were either induced or repressed by mating in the endosalpinx at 3 h post-stimulus. RT-qPCR confirmed that mating downregulated the expression of the Oas1h and Prim1 genes and upregulated the expression of the Ceacam1, Chad, Chst10, Slc5a3 and Slc26a4 genes. The functional category 'cell-to-cell signalling and interaction' was over-represented in this gene list. Network modelling identified TNF and all-trans retinoic acid (RA) as upstream regulators of the mating-induced transcriptional response, which was confirmed by intraoviductal injection of TNF or RA in unmated rats. It partially mimicked the transcriptional effect of mating in the rat endosalpinx. Furthermore, mating decreased RA levels in oviductal fluid, and RA-receptor-gamma (RARG) exhibited a nuclear location in oviductal epithelium in both unmated and mated rats, indicating RA-RARG transcriptional activity. In conclusion, the early transcriptional response regulated by mating in the rat endosalpinx is mediated by TNF and RA. These signalling molecules regulate a cohort of genes involved in 'cell-to-cell signalling and interactions' and merit further studies to understand the specific processes activated in the endosalpinx to sustain the events that occur in the mammalian oviduct early after mating.
Asunto(s)
Oviductos/metabolismo , Conducta Sexual Animal/fisiología , Transcriptoma , Tretinoina/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Animales , Femenino , Regulación de la Expresión Génica , Masculino , Membrana Mucosa/metabolismo , Ratas Sprague-Dawley , Receptores de Ácido Retinoico/metabolismo , Receptor de Ácido Retinoico gammaRESUMEN
Microbial consortia inhabiting evaporitic salt nodules at the Atacama Desert are dominated by unculturable cyanobacteria from the genus Halothece. Halite nodules provide transparency to photosynthetically active radiation and diminish photochemically damaging UV light. Atacama cyanobacteria synthesize scytonemin, a heterocyclic dimer, lipid soluble, UV-filtering pigment (in vivo absorption maximum at 370 nm) that accumulates at the extracellular sheath. Our goal was to demonstrate if UV-A irradiations modulate scytonemin biosynthesis in ground halites containing uncultured Halothece sp. cyanobacteria. Pulverized halite nodules with endolithic colonization were incubated under continuous UV-A radiation (3.6 W/m2) for 96 h, at 67% relative humidity, mimicking their natural habitat. Scytonemin content and relative transcription levels of scyB gene (a key gene in the biosynthesis of scytonemin) were evaluated by spectrophotometry and quantitative RT-PCR, respectively. After 48 h under these experimental conditions, the ratio scytonemin/chlorophyll a and the transcription of scyB gene increased to a maximal 1.7-fold value. Therefore, endolithic Halothece cyanobacteria in halites are metabolically active and UV radiation is an environmental stressor with a positive influence on scyB gene transcription and scytonemin biosynthesis. Endolithobiontic cyanobacteria in Atacama show a resilient evolutive and adaptive strategy to survive in one of the most extreme environments on Earth.
RESUMEN
Edible Llayta are cyanobacterial colonies consumed in the Andes highlands. Llayta and four isolated cyanobacteria strains were tested for cyanotoxins (microcystin, nodularin, cylindrospermopsin, saxitoxin and ß-N-methylamino-L-alanine-BMAA) using molecular and chemical methods. All isolates were free of target genes involved in toxin biosynthesis. Only DNA from Llayta amplified the mcyE gene. Presence of microcystin-LR and BMAA in Llayta extracts was discarded by LC/MS analyses. The analysed Llayta colonies have an incomplete microcystin biosynthetic pathway and are a safe food ingredient.
Asunto(s)
Toxinas Bacterianas/análisis , Suplementos Dietéticos/análisis , Nostoc/metabolismo , Altitud , Nostoc/clasificación , Nostoc/genética , HumedalesRESUMEN
In addition to the industrial and biomedical applications of lithium, information on the tolerance of microorganisms to high Li concentrations in natural biological systems is limited. Strain LCHXa is a novel free-living Gram-positive, non-motile bacterium strain isolated from water samples taken at Laguna Chaxa, a non-industrial water body with the highest soluble Li content (33 mM LiCl) within the Salar de Atacama basin in northern Chile. Enrichment was conducted in Luria-Bertani (LB) medium supplemented with 1 M LiCl. Strain LCHXa was a Novobiocin-resistant and coagulase negative Staphylococcus. Phylogenetically, strain LCHXa belongs to the species Staphylococcus sciuri. Strain LCHXa grew optimally in LB medium at pH 6-8 and 37 °C, and it was able to sustain growth at molar Li concentrations at 2 M LiCl, with a decrease in the specific growth rate of 85%. Osmoregulation in strain LCHXa partially involves glycine betaine and glycerol as compatible solutes.
RESUMEN
An extreme halophilic archaeon, strain SGH1, is a novel microorganism isolated from endolithic microbial communities colonizing halites at Salar Grande, Atacama Desert, in northern Chile. Our study provides structural, biochemical, genomic, and physiological information on this new isolate living at the edge of the physical and chemical extremes at the Atacama Desert. SGH1 is a Gram-negative, red-pigmented, non-motile unicellular coccoid organism. Under the transmission electron microscope, strain SGH1 showed an abundant electro-dense material surrounding electron-lucent globular structures resembling gas vacuoles. Strain SGH1 showed a 16S rRNA gene sequence with a close phylogenetic relationship to the extreme halophilic archaea Haloterrigena turkmenica and Haloterrigena salina and has been denominated Haloterrigena sp. strain SGH1. Strain SGH1 grew at 20-40°C (optimum 37°C), at salinities between 15 and 30% (w/v) NaCl (optimum 25%) and growth was improved by addition of 50 mM KCl and 0.5% w/v casamino acids. Growth was severely restricted at salinities below 15% NaCl and cell lysis is avoided at a minimal 10% NaCl. Maximal concentrations of magnesium chloride and sodium or magnesium perchlorates that supported SGH1 growth were 0.5 and 0.15M, respectively. Haloterrigena sp. strain SGH1 accumulates bacterioruberin (BR), a C50 xanthophyll, as the major carotenoid. Total carotenoids in strain SGH1 amounted to nearly 400 µg BR per gram of dry biomass. Nearly 80% of total carotenoids accumulated as geometric isomers of BR: all-trans-BR (50%), 5-cis-BR (15%), 9-cis-BR (10%), 13-cis-BR (4%); other carotenoids were dehydrated derivatives of BR. Carotenogenesis in SGH1 was a reversible and salt-dependent process; transferring BR-rich cells grown in 25% (w/v) NaCl to 15% (w/v) NaCl medium resulted in depigmentation, and BR content was recovered after transference and growth of unpigmented cells to high salinity medium. Methanol extracts and purified BR isomers showed an 8-9-fold higher antioxidant activity than Trolox or ß-carotene. Both, plasma membrane integrity and mitochondrial membrane potential measurements under acute 18-h assays showed that purified BR isomers were non-toxic to cultured human THP-1 cells.
RESUMEN
The interest of the food industry in replacing artificial dyes with natural pigments has grown recently. Cyanobacterial phycobiliproteins (PBPs), phycoerythrin (PE) and phycocyanin (PC), are colored water-soluble proteins that are used as natural pigments. Additionally, red PE and blue PC have antioxidant capabilities. We have formulated a new food prototype based on PBP-fortified skim milk. PBPs from Andean cyanobacteria were purified by ammonium sulfate precipitation, ion-exchange chromatography, and freeze-drying. The stability of PE and PC was evaluated by changes in their absorption spectra at various pH (1-14) and temperature (0-80 °C) values. Purified PBPs showed chemical stability under pH values of 5 to 8 and at temperatures between 0 and 50 °C. The antioxidant property of PBP was confirmed by ABTS (2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical ion scavenging, and FRAP (Ferric Antioxidant Power) assays. The absence of PBP toxicity against Caenorhabditis elegans was confirmed up to 1 mg PBP/mL. Skim milk fortified with PE obtained a higher score after sensory tests. Thus, a functional food based on skim milk-containing cyanobacterial PBPs can be considered an innovative beverage for the food industry. PBPs were stable at an ultra-high temperature (138 °C and 4 s). PBP stability improvements by changes at its primary structure and the incorporation of freeze-dried PBPs into sachets should be considered as alternatives for their future commercialization.
RESUMEN
Halites, which are typically found in various Atacama locations, are evaporitic rocks that are considered as micro-scaled salterns. Both structural and functional metagenomic analyses of halite nodules were performed. Structural analyses indicated that the halite microbiota is mainly composed of NaCl-adapted microorganisms. In addition, halites appear to harbor a limited diversity of fungal families together with a biodiverse collection of protozoa. Functional analysis indicated that the halite microbiome possesses the capacity to make an extensive contribution to carbon, nitrogen, and sulfur cycles, but possess a limited capacity to fix nitrogen. The halite metagenome also contains a vast repertory of carbohydrate active enzymes (CAZY) with glycosyl transferases being the most abundant class present, followed by glycosyl hydrolases (GH). Amylases were also present in high abundance, with GH also being identified. Thus, the halite microbiota is a potential useful source of novel enzymes that could have biotechnological applicability. This is the first metagenomic report of fungi and protozoa as endolithobionts of halite nodules, as well as the first attempt to describe the repertoire of CAZY in this community. In addition, we present a comprehensive functional metagenomic analysis of the metabolic capacities of the halite microbiota, providing evidence for the first time on the sulfur cycle in Atacama halites.
RESUMEN
Understanding the mechanisms underlying microbial resistance and resilience to perturbations is essential to predict the impact of climate change on Earth's ecosystems. However, the resilience and adaptation mechanisms of microbial communities to natural perturbations remain relatively unexplored, particularly in extreme environments. The response of an extremophile community inhabiting halite (salt rocks) in the Atacama Desert to a catastrophic rainfall provided the opportunity to characterize and de-convolute the temporal response of a highly specialized community to a major disturbance. With shotgun metagenomic sequencing, we investigated the halite microbiome taxonomic composition and functional potential over a 4-year longitudinal study, uncovering the dynamics of the initial response and of the recovery of the community after a rainfall event. The observed changes can be recapitulated by two general modes of community shifts-a rapid Type 1 shift and a more gradual Type 2 adjustment. In the initial response, the community entered an unstable intermediate state after stochastic niche re-colonization, resulting in broad predicted protein adaptations to increased water availability. In contrast, during recovery, the community returned to its former functional potential by a gradual shift in abundances of the newly acquired taxa. The general characterization and proposed quantitation of these two modes of community response could potentially be applied to other ecosystems, providing a theoretical framework for prediction of taxonomic and functional flux following environmental changes.
Asunto(s)
Microbiota , Microbiología del Suelo , Adaptación Biológica , Clima Desértico , Extremófilos/crecimiento & desarrollo , Extremófilos/metabolismo , Estudios Longitudinales , Lluvia , América del SurRESUMEN
A Gram-positive, coagulase-negative, novobiocin resistant, and lithium-tolerant bacterium was isolated from Salar de Atacama. Strain LCHXa is closely related to Staphylococcus sciuri. Its genome is 3,013,090 bp long and contains 2,551 predicted protein genes. We observed 58 genes associated with stress response and 17 genes linked to osmoregulation, mainly related to glycine betaine metabolism.
RESUMEN
Llayta is a dietary supplement that has been used by rural communities in Perú and northern Chile since pre-Columbian days. Llayta is the biomass of colonies of a Nostoc cyanobacterium grown in wetlands of the Andean highlands, harvested, sun-dried and sold as an ingredient for human consumption. The biomass has a substantial content of essential amino acids (58% of total amino acids) and polyunsaturated fatty acids (33% total fatty acids). This ancestral practice is being lost and the causes were investigated by an ethnographic approach to register the social representations of Llayta, to document how this Andean feeding practice is perceived and how much the community knows about Llayta. Only 37% of the participants (mostly adults) have had a direct experience with Llayta; other participants (mostly children) did not have any knowledge about it. These social responses reflect anthropological and cultural tensions associated with a lack of knowledge on Andean algae, sites where to find Llayta, where it is commercialized, how it is cooked and on its nutritional benefits. The loss of this ancestral feeding practice, mostly in northern Chile, is probably associated with cultural changes, migration of the rural communities, and very limited access to the available information. We propose that Llayta consumption can be revitalized by developing appropriate educational strategies and investigating potential new food derivatives based on the biomass from the isolated Llayta cyanobacterium.
RESUMEN
Fungi are generally easily dispersed, able to colonise a wide variety of substrata and can tolerate diverse environmental conditions. However, despite these abilities, the diversity of fungi in the Atacama Desert is practically unknown. Most of the resident fungi in desert regions are ubiquitous. Some of them, however, seem to display specific adaptations that enable them to survive under the variety of extreme conditions of these regions, such as high temperature, low availability of water, osmotic stress, desiccation, low availability of nutrients, and exposure to high levels of UV radiation. For these reasons, fungal communities living in the Atacama Desert represent an unknown part of global fungal diversity and, consequently, may be source of new species that could be potential sources for new biotechnological products. In this review, we focus on the current knowledge of the diversity, ecology, adaptive strategies, and biotechnological potential of the fungi reported in the different ecosystems of the Atacama Desert.
Asunto(s)
Biodiversidad , Clima Desértico , Hongos/clasificación , Microbiología del Suelo , Adaptación Fisiológica , Chile , Ecología , Ecosistema , Hongos/aislamiento & purificación , Hongos/metabolismo , Modelos BiológicosRESUMEN
Our knowledge on the Microbiology of the Atacama Desert has increased steadily and substantially during the last two decades. This information now supports a paradigmatic change on the Atacama Desert from a sterile, uninhabitable territory to a hyperarid region colonized by a rich microbiota that includes extremophiles and extreme-tolerant microorganisms. Also, extensive reports are available on the prevalent physical and chemical environmental conditions, ecological niches and, the abundance, diversity and organization of the microbial life in the Atacama Desert. This territory is a highly desiccated environment due to the absence of regular rain events. Liquid water scarcity is the most serious environmental factor affecting the Atacama Desert microorganisms. The intense solar irradiation in this region contributes, in a synergistic fashion with desiccation, to limit the survival and growth of the microbial life. In order to overcome these two extreme conditions, successful microorganisms, organized as microbial consortia, take advantage of (a) the physical characteristics of lithic habitats, which provide sites for colonization on, within or below the rock substrate, the attenuation and filtration of the intense solar irradiation and, the collection of liquid water from incoming fog formations and by water vapour condensation and deliquescence on or within their surfaces, and (b) the biological adaptations of members of the microbial communities that allow them to synthesize hydrophilic macromolecules, antioxidants and UV-light absorbents. Lithic habitats have been considered specialized shelters where life forms can reach protection at environments subjected to extremes of desiccation and solar irradiation, here on Earth or elsewhere. This review is an overview of part of the scientific information collected on lithobionts from the Atacama Desert, their rock substrates and their strategies to cope with extremes of desiccation and intense photosynthetic active radiation and UV irradiations.
Asunto(s)
Cianobacterias/crecimiento & desarrollo , Clima Desértico , Consorcios Microbianos , Microbiología del Suelo , Adaptación Fisiológica , Chile , Cianobacterias/clasificación , Humedad , Fotosíntesis , Rayos Ultravioleta , Agua/fisiologíaRESUMEN
RESUMEN Llayta es el nombre asignado a la biomasa seca de macrocolonias de una cianobacteria filamentosa, clasificada como Nostoc sp. Llayta crece en humedales andinos de Sudamérica y ha sido considerada como un ingrediente alimenticio desde tiempos precolombinos. Este estudio pretende contribuir a la definición de la calidad nutritiva de la Llayta, proporcionando información sobre su composición bioquímica e identificar aspectos críticos de interés toxicológico. Los resultados mostraron que el 60% del total de sus aminoácidos son indispensables, contenía un 2% de lípidos totales, 32% del total de ácidos grasos eran poliinsaturados, la vitamina E fue la más abundante (4,3 mg%), el contenido de polifenoles totales es 64 mg equivalentes de ácido gálico, su actividad antioxidante es 17,4 μmoles equivalentes de Trolox, la fibra total fue el 56% del peso seco y presentó un contenido promedio de arsénico total de 9,2 ± 5,4 ppm. Esta cianobacteria no es productora de microcistina, por lo que las colonias de la Llayta podrían considerarse inocua para el consumo humano.
ABSTRACT Llayta is the name assigned to the dry biomass of macrocolonies of a filamentous cyanobacterium classified as Nostoc sp. Llayta grows in the Andean wetlands of South America and has been considered a food ingredient since pre-Columbian times. This work is an effort to contribute to define the nutritional quality of Llayta providing information on its biochemical composition and to identify key toxicological aspects. The results indicated that 60% of its aminoacids were indispensable, total lipids were 2% of dry weight, polyunsaturated fatty acids were 32% of total fatty acids, vitamin E was the most abundant (4.3 mg%), total polyphenols were 64 mg (equivalent to galic acid), antioxidant activity was 17.4 μmoles (equivalent to Trolox), total fiber was 56% of dry weight and accumulated 9.2 ± 5.4 ppm of total arsenic. Since Nostoc sp. Llayta is a cyanobacterium strain that does not synthesize the cyanotoxin microcystin, the Llayta colonies can be considered innocuous for human consumption.