Global Distribution and Diversity of Haloarchaeal pL6-Family Plasmids.

Australian isolates of Haloquadratum walsbyi, a square-shaped haloarchaeon, often harbor small cryptic plasmids of the pL6-family, approximately 6 kb in size, and five examples have been previously described. These plasmids exhibit a highly conserved gene arrangement and encode replicases similar to those of betapleolipoviruses. To assess their global distribution and recover more examples for analysis, fifteen additional plasmids were reconstructed from the metagenomes of seven hypersaline sites across four countries: Argentina, Australia, Puerto Rico, and Spain. Including the five previously described plasmids, the average plasmid size is 6002 bp, with an average G+C content of 52.5%. The tetramers GGCC and CTAG are either absent or significantly under-represented, except in the two plasmids with the highest %G+C. All plasmids share a similar arrangement of genes organized as outwardly facing replication and ATPase modules, but variations were observed in some core genes, such as F2, and some plasmids had acquired accessory genes. Two plasmids, pCOLO-c1 and pISLA-c6, shared 92.7% nt identity despite originating from Argentina and Spain, respectively. Numerous metagenomic CRISPR spacers matched sequences in the fifteen reconstructed plasmids, indicating frequent invasion of haloarchaea. Spacers could be assigned to haloarchaeal genera by mapping their associated direct repeats (DR), with half of these matching Haloquadratum. Finally, strand-specific metatranscriptome (RNA-seq) data could be used to demonstrate the active transcription of two pL6-family plasmids, including antisense transcripts.

Microplastic evidence assessment from water and sediment sampling in a shallow tropical lake.

Microplastics (MPs) severely threaten inland waterbodies due to the direct impact of human activities. In the present study, spatial and temporal patterns of MPs in a shallow tropical lake were assessed, describing their size, morphology, and polymer types. Water and sediment samples were collected from Lake Chapala during three seasons, and MPs were quantified with a stereomicroscope. The structure, elemental composition, and polymeric composition were determined via environmental scanning electron microscopy and Fourier transform infrared spectroscopy. The highest average concentration of microplastics in Lake Chapala was detected during the low-water period in April 2022 (2.35 items/L), exceeding the July 2022 rainy season concentration (1.8 items/L) by 0.25 items/L, and sediment concentrations were also higher in April 2022 (219 items/kg) compared to July 2022 (210 items/kg). This study highlights the significant pollution of Lake Chapala with microplastics, emphasizing the need for urgent measures to manage plastic waste and mitigate its environmental impact on aquatic ecosystems. PRACTITIONER POINTS: Microplastic contamination was evaluated in Lake Chapala. The distribution profiles of microplastics were different in each area. Heavy metals osmium, tellurium, and rhodium were found associated with the PMs. Polymers were found in this study.

Metagenome-Assembled Genome of "Candidatus Aramenus sp. CH1" from the Chichon volcano, Mexico.

The Chichon volcano contains several thermal manifestations including an acidic crater lake. Here we report a metagenome-assembled genome of "Candidatus Aramenus sp. CH1," a Sulfolobales archaeon inhabiting the crater lake from the Chichon volcano. In this study, we generated a novel Aramenus genome sequence from a thermal area in Southern Mexico.

Assessing the effects of long-term mining exploitation on a lacustrine system from the arid region of the Atacama Desert, Chile.

Over the last century, the Atacama Desert has been exploited due to the mineral resources in this environment. These anthropogenic effects have primarily been linked to the development of the mining industry, the impact of which remains uncertain. Here, we use high-resolution geochemical characterization and magnetic properties analysis from the sedimentary core of Inka Coya Lake, located in the Atacama Desert, to assess the anthropogenic impact in this metallogenic region. The geochemistry and magnetic properties changed with core depth. Elements, such as Cu, Ni, and Zn, increased during the lake's most recent period. Additionally, an increase in mass magnetic susceptibility (χ) and a decrease in magnetic susceptibility depending on the frequency (χfd%) may be attributed to fine iron oxide grains originating from industrial and urban sources. Moreover, indices of pollution classified the sediment of Inka Coya Lake as slightly polluted and strongly polluted with Ni, and Cu, respectively. This could reflect a period of pollution caused by the increase in the production of copper sulfide. These results highlight the possible impact of mining activities in the hyper-arid core of the Atacama Desert, which affects surrounding areas through dispersive processes, even reaching high altitudes, and provides a scientific basis for the prevention of environmental pollution from mining and the protection of the sediment and water source in the Atacama Desert.

Occurrence and potential ecological risks of PFAS in Pampulha Lake, Brazil, a UNESCO world heritage site.

Per- and polyfluoroalkyl substances (PFAS) comprise >4000 synthetic substances used in industrial applications and consumer products. PFAS used daily in households and manufacturing plants end up in domestic sewage, and industrial effluents can be discharged to surface water. Urban watersheds located in low and middle-income countries (LMIC), which lack sanitation infrastructure, are potential recipients of waste containing PFAS. Yet, only a few studies report PFAS occurrence in urban reservoirs and lakes, especially those located in the Global South due to resource limitations. This is the first study aimed to assess PFAS occurrence and ecological risks in Pampulha Lake, Brazil, a site which represents the reality of many other urban watersheds in LMIC as it is surrounded by densely populated areas and manufacturing plants. Surface water samples were collected monthly for 1 year from four sampling points at Pampulha Lake. Sample analysis was based on US Environmental Protection Agency Method 1633, which employs solid phase extraction followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Species sensitivity distribution (SSD) curves were built to identify potentially susceptible species based on detected water concentrations. Bioaccumulation was estimated for fish tissue. Short-chain (perfluorobutanesulfonic acid, PFBS and perfluorohexanoic acid, PFHxA) and long-chain PFAS (perfluorodecanoic acid, PFDA; perfluorooctanoic acid, PFOA; perfluorododecanoic acid, PFDoA; and perfluorooctanesulfonic acid, PFOS) were detected at the µg L-1 range. Total PFAS concentrations in the wet season were generally higher than in the dry season, likely due to limited capacity of the treatment plant processing water from tributaries which receive raw sewage. More than 5 % of aquatic species are potentially susceptible to chronic effects of PFOS at detected concentrations (0.2-2.2 µg L-1). Predicted bioaccumulation of PFOS in fish was above advisory diet intake levels for humans. Results emphasize the need for studies related to PFAS occurrence in watersheds located in LMIC.

Abiotic processes control carbon dioxide dynamics in temperate karst lakes.

Inland waters are crucial in the carbon cycle, contributing significantly to the global CO2 fluxes. Carbonate lakes may act as both sources and sinks of CO2 depending on the interactions between the amount of dissolved inorganic carbon (DIC) inputs, lake metabolisms, and geochemical processes. It is often difficult to distinguish the dominant mechanisms driving CO2 dynamics and their effects on CO2 emissions. This study was undertaken in three groundwater-fed carbonate-rich lakes in central Spain (Ruidera Lakes), severely polluted with nitrates from agricultural overfertilization. Diel and seasonal (summer and winter) changes in CO2 concentration (CCO2) DIC, and CO2 emissions-(FCO2)-, as well as physical and chemical variables, including primary production and phytoplanktonic chlorophyll-a were measured. In addition, δ13C-DIC, δ13C-CO2 in lake waters, and δ13C of the sedimentary organic matter were measured seasonally to identify the primary CO2 sources and processes. While the lakes were consistently CCO2 supersaturated and FCO2 was released to the atmosphere during both seasons, the highest CCO2 and DIC were in summer (0.36-2.26 µmol L-1). Our results support a strong phosphorus limitation for primary production in these lakes, which impinges on CO2 dynamics. External DIC inputs to the lake waters primarily drive the CCO2 and, therefore, the FCO2. The δ13C-DIC signatures below -12‰  confirmed the primary geogenic influence on DIC. As also suggested by the high values on the calcite saturation index, the Miller-Tans plot revealed that the CO2 source in the lakes was close to the signature provided by the fractionation of δ13C-CO2 from calcite precipitation. Therefore, the main contribution behind the CCO2 values found in these karst lakes should be attributed to the calcite precipitation process, which is temperature-dependent according to the seasonal change observed in δ13C-DIC values. Finally, co-precipitation of phosphate with calcite could partly explain the observed low phytoplankton production in these lakes and the impact on the contribution to increasing greenhouse gas emissions. However, as eutrophication increases and the soluble reactive phosphorus (SRP) content increases, the co-precipitation of phosphate is expected to be progressively inhibited. These thresholds must be assessed to understand how the CO32- ions drive lake co-precipitation dynamics. Carbonate regions extend over 15% of the Earth's surface but seem essential in the CO2 dynamics at a global scale.

A metagenomic study of antibiotic resistance genes in a hypereutrophic subtropical lake contaminated by anthropogenic sources.

Antibiotic resistance genes (ARGs) are a major threat to human and environmental health. This study investigated the occurrence and distribution of ARGs in Lake Cajititlán, a hypereutrophic subtropical lake in Mexico contaminated by anthropogenic sources (urban wastewater and runoff from crop and livestock production). ARGs (a total of 475 genes) were detected in 22 bacterial genera, with Pseudomonas (144 genes), Stenotrophomonas (88 genes), Mycobacterium (54 genes), and Rhodococcus (27 genes) displaying the highest frequencies of ARGs. Among these, Pseudomonas aeruginosa and Stenotrophomonas maltophilia showed the highest number of ARGs. The results revealed a diverse array of ARGs, including resistance to macrolides (11.55 %), aminoglycosides (8.22 %), glycopeptides (6.22 %), tetracyclines (4 %), sulfonamides (4 %), carbapenems (1.11 %), phenicols (0.88 %), fluoroquinolones (0.44 %), and lincosamides (0.22 %). The most frequently observed ARGs were associated with multidrug resistance (63.33 %), with MexF (42 genes), MexW (36 genes), smeD (31 genes), mtrA (25 genes), and KHM-1 (22 genes) being the most common. Lake Cajititlán is a recreational area for swimming, fishing, and boating, while also supporting irrigation for agriculture and potentially acting as a drinking water source for some communities. This raises concerns about the potential for exposure to antibiotic-resistant bacteria through these activities. The presence of ARGs in Lake Cajititlán poses a significant threat to both human and environmental health. Developing strategies to mitigate the risks of antibiotic resistance, including improving wastewater treatment, and promoting strategic antibiotic use and disposal, is crucial. This study represents a significant advancement in the understanding of antibiotic resistance dynamics in a hypereutrophic subtropical lake in a developing country, providing valuable insights for the scientific community and policymakers.

Usefulness of oxidative stress biomarkers in native species for the biomonitoring of pesticide pollution in a shallow lake of the Austral Pampas, Argentina.

Pesticide contamination and its adverse effects on native freshwater species continue to be a worldwide major concern, mainly in developing countries. Passive biomonitoring of pesticide pollution in shallow lakes may be achieved by the simultaneous use of fish and wetland plants. Thus, the present study aimed to evaluate the occurrence of current-use pesticides in the surface water of a shallow lake of the Austral Pampas region (Buenos Aires Province, Argentina) surrounded by intensive agricultural activities and its relationship with a battery of biomarkers, including oxidative stress and genotoxicity, in two native species, the fish Oligosarcus jenynsii and the macrophyte Bidens laevis. A total of 26 pesticide residues were analyzed, and the main ones detected were glyphosate and its metabolite aminomethylphosphonic acid (AMPA), chlorpyrifos, and imidacloprid. In O. jenynsii, hydrogen peroxide (H2O2) content in the liver increased with chlorpyrifos occurrence, while malondialdehyde (MDA) levels in the brain and liver increased with the presence of both chlorpyrifos and glyphosate. In B. laevis, H2O2 and MDA levels in leaves and roots increased with AMPA occurrence. Also, leaf H2O2 contents and root MDA levels increased with chlorpyrifos concentration. In contrast, catalase and peroxidase activities in roots decreased with AMPA and chlorpyrifos occurrence. In both species, mainly H2O2 and MDA levels demonstrated their sensitivity to be used as biomarkers in the biomonitoring of current-use pesticide pollution in shallow lakes. Their use may provide information to plan strategies for environmental conservation by government institutions or decision-makers, and to assess the biota health status.

Seasonality of hydrogeochemical evolutions and isotopic variabilities (δ18O, δ2H and d-excess) in the surface water as well as groundwater from tropical central-south Mexico.

Due to adverse impact of the global warming on hydrological resources, we intended to document the hydrogeochemical evolutions of surface and groundwater at tropical central-south Mexico in terms of seasonality of rock-water interaction, precipitation/evaporation variation and moisture source by evaluating the major ion chemistry in Piper and Gibbs plots, Durov diagram and through estimation of the chloro-alkaline indices as well as assessing the stable isotope compositions (δ18O and δ2H) in samples from different seasons of a year. Surface water of the Lake Coatetelco shifted from mostly Ca-Mg-HCO3 facies in wet summer-autumn to Na-HCO3-Cl facies in the dry spring due to elevated Na, Cl and HCO3. Greater evaporation in spring led to a maximum δ18O enrichment of ca.7‰ compared to the other seasons, and much depleted deuterium excess (-40.92‰ to -39.20‰). Interaction of the lake water with subsurface carbonate lithologies, and comparable isotopic compositions reflected the enhanced interaction between the surface water body and aquifers in the wet autumn. Effect of seasonality, however, was unclear on the groundwater facies, and its heterogenous composition (Ca-Mg-HCO3, Na-HCO3-Cl and Na-HCO3) reflected the interactions with different lithologies. Fractionations in isotope compositions of the groundwater were caused from recharge at different elevations, seasonality of moisture sources and moisture recycling. The water-mineral saturation index was an efficient proxy of seasonality as the lake water and groundwater (avg SIcalcite > 0.5) of the dry autumn were saturated with calcite. This vital information about carbonate precipitation, pCO2 and chemical facies would be useful for the better interpretation of paleoclimate archives in this region.

Nutrient structure dynamics and microbial communities at the water-sediment interface in an extremely acidic lake in northern Patagonia.

Lake Caviahue (37° 50 'S and 71° 06' W; Patagonia, Argentina) is an extreme case of a glacial, naturally acidic, aquatic environment (pH ~ 3). Knowledge of the bacterial communities in the water column of this lake, is incipient, with a basal quantification of the bacterioplankton abundance distribution in the North and South Basins of Lake Caviahue, and the described the presence of sulfur and iron oxidizing bacteria in the lake sediments. The role that bacterioplankton plays in nutrient utilization and recycling in this environment, especially in the phosphorus cycle, has not been studied. In this work, we explore this aspect in further depth by assessing the diversity of pelagic, littoral and sediment bacteria, using state of the art molecular methods and identifying the differences and commonalties in the composition of the cognate communities. Also, we investigate the interactions between the sediments of Lake Caviahue and the microbial communities present in both sediments, pore water and the water column, to comprehend the ecological relationships driving nutrient structure and fluxes, with a special focus on carbon, nitrogen, and phosphorus. Two major environmental patterns were observed: (a) one distinguishing the surface water samples due to temperature, Fe2+, and electrical conductivity, and (b) another distinguishing winter and summer samples due to the high pH and increasing concentrations of N-NH4+, DOC and SO42-, from autumn and spring samples with high soluble reactive phosphorus (SRP) and iron concentrations. The largest bacterial abundance was found in autumn, alongside higher levels of dissolved phosphorus, iron forms, and increased conductivity. The highest values of bacterial biomass were found in the bottom strata of the lake, which is also where the greatest diversity in microbial communities was found. The experiments using continuous flow column microcosms showed that microbial growth over time, in both the test and control columns, was accompanied by a decrease in the concentration of dissolved nutrients (SRP and N-NH4+), providing proof that sediment microorganisms are active and contribute significantly to nutrient utilization/mobilization.

Genomic Diversity and Zoonotic Potential of Brucella neotomae.

After reports in 2017 of Brucella neotomae infections among humans in Costa Rica, we sequenced 12 strains isolated from rodents during 1955-1964 from Utah, USA. We observed an exact strain match between the human isolates and 1 Utah isolate. Independent confirmation is required to clarify B. neotomae zoonotic potential.

Modeling stabilizing the of orchard managers on the shores of Lake Urmia against late spring frost / Modelo de estabilização dos meios de subsistência dos pomares nas margens do Lago Urmia contra as geadas do final da primavera

Despite the adverse effects of late spring frost on the ecological and economic impact on agriculture, the management of these events are poorly investigated. Therefore, the grounded theory was used for extracting the livelihood stabilization model of orchardists on the shores of Lake Urmia against late spring frosts. The statistical population of this study in the qualitative part included 22 experts in the field of horticulture. In the quantitative study, they included all orchardists in the villages along with Lake Urmia, comprising 341 people, of which 236 were randomly selected. By carefully examining and linking the concepts and subcategories, the most important subcategories that were included six subcategories. The results of all calculated goodness-of-fit indexes (chi-square [P > 0.01], RMSEA = 0.000, NFI = 0.95, CFI = 0.91, and GFI = 0.92) showed the model provided an excellent fit for the data. Standardized regression coefficients showed that interfering factors had the greatest impact on the livelihood of orchardists against late spring frosts (ß = 0.47). Also, the background factors (ß = 0.43) and causal factors (ß = 0.39) were found to affect the livelihood of the orchardists in encountering late spring frost. The results of multiple square correlations of dependent variables also indicated that about 41% of the livelihood variance of small-scale orchardists was explained by the predictor variables (i.e. causal conditions, background factors and interfering factors). The findings of this study can assist policymakers, planners and relevant managers while paying more attention to orchardists in the region, so as to support decisions in order to achieve sustainable development.

Apesar dos efeitos adversos das geadas do final da primavera no impacto ecológico e econômico na agricultura, o manejo desses eventos é pouco investigado. Portanto, a teoria fundamentada foi utilizada para extrair o modelo de estabilização dos meios de subsistência dos pomares nas margens do Lago Urmia contra as geadas do final da primavera. A população estatística deste estudo na parte qualitativa incluiu 22 especialistas na área de horticultura. O estudo quantitativo incluiu todos os fruticultores nas aldeias junto ao Lago Urmia, compreendendo 341 pessoas, das quais 236 foram selecionadas aleatoriamente. Ao examinar cuidadosamente e vincular os conceitos e subcategorias, as subcategorias mais importantes que foram incluídas em outras 6 subcategorias. Os resultados de todos os índices de qualidade de ajuste calculados (qui-quadrado [P > 0,01], RMSEA = 0,000, NFI = 0,95, CFI = 0,91 e GFI = 0,92) mostraram que o modelo forneceu um excelente ajuste para os dados. Os coeficientes de regressão padronizados mostraram que os fatores interferentes tiveram o maior impacto sobre a subsistência dos pomares contra as geadas do final da primavera (ß = 0,47). Além disso, descobriu-se que os fatores de fundo (ß = 0,43) e os fatores causais (ß = 0,39) afetam o sustento dos pomares ao enfrentarem geadas no final da primavera. Os resultados de múltiplas correlações quadradas de variáveis dependentes também indicaram que cerca de 41% da variância dos meios de subsistência de pequenos pomares foi explicada pelas variáveis preditoras, ou seja, condições causais, fatores de fundo e fatores interferentes. Os resultados deste estudo podem auxiliar os formuladores de políticas, planejadores e gestores relevantes, dando mais atenção aos pomares da região, de modo a apoiar as decisões a fim de alcançar o desenvolvimento sustentável.

Identificação de polímeros de microplásticos encontrados no trato digestivo de peixes do Lago de Amatitlán, Guatemala / Identification of microplastic polymers found in the digestive tract of fish from Lake Amatitlán, Guatemala

O objetivo desta pesquisa foi a identificação, por meio de espectroscopia no infravermelho com transformada de Fourier combinada com reflectância total atenuada (FTIR-ATR), de microplásticos extraídos do trato gastrointestinal de peixes coletados no Lago de Amatitlán, para determinar os principais polímeros e a possível origem da contaminação por esses materiais. Foram analisados 68 microplásticos, correspondendo a 10% do total de microplásticos extraídos. Estes originaram-se de 36 espécimes, sendo 35 da espécie Oreochromis niloticus e um de Parachromis managuensis, dos quais foram analisados de 1 a 5 microplásticos por espécime. Os polímeros identificados foram polipropileno (PP), nylon, polietileno de alta densidade (HDPE), tereftalato de polietileno (PET), látex, poliestireno (PE), polietileno de baixa densidade (LDPE) e poliuretano (PU). O polipropileno (32), o polietileno de alta densidade (13) e o nylon (10) foram os polímeros mais frequentes. Os possíveis itens plásticos que podem ter originado os microplásticos incluem brinquedos, equipamentos de laboratório, baldes, embalagens de alimentos, tubulações, isolamento para cabos, têxteis, cordas e móveis que são produzidos na indústria do plástico, localizada principalmente na vertente sul da cidade da Guatemala. Além disso, as espécies de peixes do presente estudo sustentam pescarias importantes, o que levanta problemas de saúde humana, uma vez que a ingestão de peixes que consomem plásticos tem o potencial de aumentar a carga corporal de substâncias químicas perigosas, pois estas aderem superficialmente aos plásticos no ambiente e são posteriormente bioacumuladas.

The objective of this research was the identification, through Fourier transform infrared spectroscopy combined with attenuated total reflectance (FTIR-ATR), of microplastics extracted from the gastrointestinal tract of fish collected in Lake Amatitlán, to determine the main polymers and the possible origin of contamination by these materials. 68 microplastics were analyzed, corresponding to 10% of the total microplastics extracted. These originated from 36 specimens, 35 of the species Oreochromis niloticus and one of Parachromis managuensis, of which 1 to 5 microplastics per specimen were analyzed. The polymers identified were polypropylene (PP), nylon, high-density polyethylene (HDPE), polyethylene terephthalate (PET), latex, polystyrene (PE), low-density polyethylene (LDPE) and polyurethane (PU). Polypropylene (32), high-density polyethylene (13) and nylon (10) were the most frequent polymers. Possible plastic items that may have caused microplastics include toys, laboratory equipment, buckets, food packaging, pipes, insulation for cables, textiles, ropes and furniture that are produced in the plastics industry, located mainly on the south side of Guatemala City. Furthermore, the fish species in the present study support important fisheries, which raises human health concerns, since the ingestion of fish that consume plastics has the potential to increase the body load of dangerous chemicals, as they adhere superficially to the plastics in the environment and are subsequently bioaccumulated.

The Raphidiopsis (= Cylindrospermopsis) raciborskii pangenome updated: Two new metagenome-assembled genomes from the South American clade.

Two Raphidiopsis (=Cylindrospermopsis) raciborskii metagenome-assembled genomes (MAGs) were recovered from two freshwater metagenomic datasets sampled in 2011 and 2012 in Pampulha Lake, a hypereutrophic, artificial, shallow reservoir, located in the city of Belo Horizonte (MG), Brazil. Since the late 1970s, the lake has undergone increasing eutrophication pressure, due to wastewater input, leading to the occurrence of frequent cyanobacterial blooms. The major difference observed between PAMP2011 and PAMP2012 MAGs was the lack of the saxitoxin gene cluster in PAMP2012, which also presented a smaller genome, while PAMP2011 presented the complete sxt cluster and all essential proteins and clusters. The pangenome analysis was performed with all Raphidiopsis/Cylindrospermopsis genomes available at NCBI to date, with the addition of PAMP2011 and PAMP2012 MAGs (All33 subset), but also without the South American strains (noSA subset), and only among the South American strains (SA10 and SA8 subsets). We observed a substantial increase in the core genome size for the 'noSA' subset, in comparison to 'All33' subset, and since the core genome reflects the closeness among the pangenome members, the results strongly suggest that the conservation level of the essential gene repertoire seems to be affected by the geographic origin of the strains being analyzed, supporting the existence of a distinct SA clade. The Raphidiopsis pangenome comprised a total of 7943 orthologous protein clusters, and the two new MAGs increased the pangenome size by 11%. The pangenome based phylogenetic relationships among the 33 analyzed genomes showed that the SA genomes clustered together with 99% bootstrap support, reinforcing the metabolic particularity of the Raphidiopsis South American clade, related to its saxitoxin producing unique ability, while also indicating a different evolutionary history due to its geographic isolation.

Genome analysis of haloalkaline isolates from the soda saline crater lake of Isabel Island; comparative genomics and potential metabolic analysis within the genus Halomonas.

BACKGROUND: Isabel Island is a Mexican volcanic island primarily composed of basaltic stones. It features a maar known as Laguna Fragatas, which is classified as a meromictic thalassohaline lake. The constant deposition of guano in this maar results in increased levels of phosphorus, nitrogen, and carbon. The aim of this study was to utilize high-quality genomes from the genus Halomonas found in specialized databases as a reference for genome mining of moderately halophilic bacteria isolated from Laguna Fragatas. This research involved genomic comparisons employing phylogenetic, pangenomic, and metabolic-inference approaches. RESULTS: The Halomonas genus exhibited a large open pangenome, but several genes associated with salt metabolism and homeostatic regulation (ectABC and betABC), nitrogen intake through nitrate and nitrite transporters (nasA, and narGI), and phosphorus uptake (pstABCS) were shared among the Halomonas isolates. CONCLUSIONS: The isolated bacteria demonstrate consistent adaptation to high salt concentrations, and their nitrogen and phosphorus uptake mechanisms are highly optimized. This optimization is expected in an extremophile environment characterized by minimal disturbances or abrupt seasonal variations. The primary significance of this study lies in the dearth of genomic information available for this saline and low-disturbance environment. This makes it important for ecosystem conservation and enabling an exploration of its biotechnological potential. Additionally, the study presents the first two draft genomes of H. janggokensis.

Changes in the abundance and diversity of bacterial and archaeal communities at different depths in a eutrophic freshwater lake in southwestern Mexico.

Bacteria and archaea play a fundamental role in the biogeochemical cycles of organic matter, pollutants, and nutrients to maintain the trophic state of aquatic ecosystems. However, very little is known about the composition patterns of microbial communities in vertical distribution (water column) in freshwater lakes and their relationship with the physicochemical properties of water. "La Encantada" lake in the Lagunas de Montebello National Park (LMNP) is a site of interest due to the anthropogenic impact received and the little information about it. In this study, 3 sites were evaluated; samples were collected using 0-15 m deep water columns and analyzed using Illumina MiSeq sequencing technology based on the 16S rRNA gene. The physical parameters of pH, temperature, dissolved oxygen, electrolytic conductivity, and PO-4 were determined. The results revealed clear differences in the microbial composition of the water throughout the column; the most abundant phyla in bacterial communities were Proteobacteria (23.2%), Cyanobacteria (17.3%), and Bacteroidetes (17.2%), and for archaea were Crenarchaeota (35.9%) and Euryarchaeota (33.2%). PICRUSt metabolic inference analysis revealed that the main functional genes were related to cellular processes and biodegradation of xenobiotics, indicating an increasing trend of contaminants and residual discharges that may act as a precursor to alter microbial communities and stability of the lakes. At depths of 10 and 15 m, the microbial diversity was greater; likewise, the correlation between the physicochemical parameters and the microbial communities at the genus level showed that Chlorobaculum, Desulfomonile, and Candidatus Xiphinematobacter were favored by an increase in dissolved phosphates and by the decrease in pH and temperature. These results highlight that the microbial communities exhibit variation in their composition due to the effect of depth and physicochemical parameters, which could play a role as biological factors in the trophic states of a lake.

Vertical distribution of beta diversity of macroinvertebrates in an oligotrophic high mountain neotropical lake / Distribución vertical de la diversidad beta de macroinvertebrados en un lago oligotrófico de alta montaña neotropical

RESUMEN Los componentes alfa (α) y beta (ß) de la diversidad gamma (γ), y la partición de ß en anidamiento y recambio, contribuyen a entender los factores que determinan la diversidad biológica. El objetivo de este estudio fue entender los factores que afectan los cambios espaciales de diversidad de macroinvertebrados en lagos andinos tropicales de alta montaña, a partir del estudio de los componentes de diversidad y la partición de la diversidad ß. Para esto, se realizó un muestreo en noviembre de 2018, en un lago ubicado a 3740 m.s.n.m. Se recolectaron macroinvertebrados bentónicos en 20 sitios distribuidos en las zonas litoral, sublitoral y profunda. In situ, se midieron profundidad, temperatura, pH, conductividad y oxígeno disuelto; se realizaron perfiles verticales de oxígeno y temperatura. Se evaluaron los componentes de riqueza mediante el modelo γ= α +ß. Se realizaron: análisis de regresión entre a y g, análisis de disimilitud a partir de la partición de la diversidad ß en recambio y anidamiento, Escalamiento Multidimensional no Métrico (nMDS) y Porcentaje de Similaridad (Simper). Los resultados mostraron que la diversidad a por sitios y zonas del lago es baja con relación a la diversidad g, y la diversidad ß es alta. Esto indica que los lagos tropicales andinos de alta montaña, a pesar de su pequeño tamaño, son importantes para una alta diversidad de macroinvertebrados. La riqueza taxonómica depende de las variaciones ambientales en los gradientes vertical y horizontal. Sin embargo, estos lagos son vulnerables a tensores naturales y antrópicos como el calentamiento global.

ABSTRACT The alpha (α) and beta (ß) components of gamma (γ) diversity, and the partitioning of ß into nesting and turnover, contribute to understanding the factors that determine biological diversity. The objective of this study was to understand the factors affecting spatial changes in macroinvertebrate diversity in tropical high mountain Andean lakes, from the study of diversity components and beta diversity partitioning. For this, sampling was conducted in November 2018, in a lake located at 3740 m.a.s.l. Benthic macroinvertebrates were collected in 20 sites distributed in littoral, sublittoral and deep zones. In situ, depth, temperature, pH, conductivity and dissolved oxygen were measured; vertical profiles of oxygen and temperature were made. Richness components were evaluated using the γ= α +ß model. Regression analysis between a and g, dissimilarity analysis from the partitioning of beta diversity into turnover and nesting, Non-Metric Multidimensional Scaling (nMDS) and Percent Similarity (Simper) were performed. The results showed that a diversity by sites and lake zones is low relative to g diversity, and ß diversity is high. This indicates that high mountain tropical Andean lakes, despite their small size, are important for high macroinvertebrate diversity. Taxonomic richness depends on environmental variations in gradients vertically and horizontally. However, these lakes are vulnerable to natural and anthropogenic stressors such as global warming.

Analysis of the microbiome of the Bolivian high-altitude Lake Pastos Grandes.

Lake Pastos Grandes in Bolivia is mainly composed of salt flats, which are sporadically and only partially submerged during the wet season. In the present study, the chemical composition of water samples of the lake and some influent rivers was determined. We found that it is likely that the lake was influenced by the dilution of metals from ancient evaporites. We performed the first metagenomic studies of this lake. Analyses of shotgun metagenomics revealed that the relative abundances of Burkholderiales and Pseudomonadales were noteworthy in the water samples, whereas the archaea belonging to the Halobacteriales and Cyanobacteria from subsection III had high abundances in the salt flat. The eukaryotes Crustacea and Diatomea exhibited the highest abundances in the water samples. We investigated further the potential effect of human activities on the nitrogen cycle mobilization in the lake and the propagation of antimicrobial resistance genes. This is the first report about the cycle in the lake. Additionally, rifamycin resistance genes and genes related to efflux pumps, which are not considered a hazard when identified in metagenomes, had the uppermost relative abundances in all sampling points. We found that Lake Pastos Grandes hitherto does not show an appreciable influence by anthropogenic actions.

Socioeconomic indices guided linear mixed-effects and meta-regression modelling of the temporal, global and regional prevalence of Helicobacter pylori in environmental waters: A class I carcinogen.

Environmental waters (EW) substantially lend to the transmission of Helicobacter pylori (Hp). But the increase in Hp infections and antimicrobial resistance is often attributed to socioeconomic status. The connection between socioeconomic status and Hp prevalence in EW is however yet to be investigated. This study aimed to assess the impacts of socioeconomic indices (SI: continent, world bank region (WBR), world bank income (WBI), WHO region, Socio-demographic Index (SDI quintile), Sustainable Development Index (SuDI), and Human Development Index (HDI)) on the prevalence of Hp in EW. Hp-EW data were fitted to a generalized linear mixed-effects model and SI-guided meta-regression models with a 1000-resampling test. The worldwide prevalence of Hp in EW was 21.76% [95% confidence interval [CI]: 10.29-40.29], which declined significantly from 59.52% [43.28-74.37] in 1990-99 to 19.36% [3.99-58.09] in 2010-19 and with increasing trend in 2020-22 (33.33%, 22.66-45.43). Hp prevalence in EW was highest in North America (45.12%, 17.07-76.66), then Europe (22.38%, 5.96-56.74), South America (22.09%, 13.76-33.49), Asia (2.98%, 0.02-85.17), and Africa (2.56%, 0.00-99.99). It was negligibly different among sampling settings, WBI, and WHO regions demonstrating highest prevalence in rural location [42.62%, 3.07-94.56], HIEs [32.82%, 13.19-61.10], and AMR [39.43%, 19.92-63.01], respectively. However, HDI, sample size, and microbiological method robustly predict Hp prevalence in EW justifying 26.08%, 21.15%, and 16.44% of the true difference, respectively. In conclusion, Hp is highly prevalence in EW across regional/socioeconomic strata and thus challenged the uses of socioeconomic status as surrogate for hygienic/sanitary practices in estimating Hp infection prevalence.

Chronostratigraphy elucidates environmental changes in lacustrine sedimentation rates and metal accumulation.

All changes taking place in a watershed have repercussions on lacustrine environments, being these, the sink of all activities occurring in the basin. Lake Titicaca, the world's highest and navigable lake, is not unfamiliar with these phenomena that can alter the sedimentation dynamics and metal accumulation. This study aimed to identify temporal trends of sedimentation rates by employing a geochronological analysis (210Pb, 137Cs) and to propose metal background values in Puno Bay, as well as to identify metal concentrations (As, Ba, Ca, Cr, Cu, K, Mg, Mo, Ni, Pb, Zn) in the projected timeline to propose, for the first time, background values in Puno Bay. Two sediment cores were collected from the outer and inner bays. Sediment rate (SR) was calculated through the excess of 210Pb (210Pbxs) applying the Constant Flux Constant Sedimentation (CFCS) model. Results show that SR in the outer bay was 0.48 ± 0.08 cm a-1 and for the inner bay was 0.64 ± 0.07 cm a-1. Sediment quality guidelines (SQGs) did not indicate toxicity was likely to occur, except for As. However, enrichment factors (EFs) indicated that all metal accumulation is geogenic. Climatic factors had a marked influence on sedimentation rates for the outer bay, and in the case of the inner bay, it was a sum of climatic and human-based factors.