Development of a green and low-cost method to determine mercury content in sediments affected by oil spill on the Brazilian coast.

Tons of crude oil were found on the Brazilian coast in 2019, and studies assessing its chemical composition are still scarce. This study aimed to develop a new and simple technique of cold vapor generation using infrared irradiation coupled with atomic absorption spectrometry to determine mercury content in sediments contaminated by crude oil. Experimental conditions were evaluated, including formic acid concentration, reactor temperature, and carrier gas flow rate. The accuracy of the method was validated by comparison with mercury contents in a certified reference material (PACS-2). The detection limit was found to be 0.44 µg kg-1. The developed method was applied to determine the total mercury content in marine sediment samples collected from beaches in Ceará State. Mercury concentrations ranged from 0.41 to 0.95 mg kg-1. The proposed method is efficient, simple, low-cost, and adequate for its purpose.

Challenges of aerobic granular sludge utilization: Fast start-up strategies and cationic pollutant removal.

Aerobic granular sludge (AGS) is a self-aggregated microorganism consortium with pollutant removal properties. The aim of this work is to study and review the application of aerobic granules for water treatment with special focus on new applications and methodologies. Carbon-nitrogen containing pollutants are the classic targets of AGS technology. Carbon and nitrogen removal of AGS are classified as a biodegradation process. More recently, the AGS granules have been studied as sorbent materials for wastewater treatment. In particular, the sorption of cationic pollutants has been studied through biosorption and bioaccumulation mechanisms without distinguishing when one or the other process is involved. AGS conformation made them suitable for complex wastewater treatment. Indeed, several studies have demonstrated the removal of polyvalent cationic pollutants even with higher capacity than conventional sorbent materials. However, this was achieved almost exclusively for synthetic substrates, with single cation evaluation and using in some cases only qualitative measures. For successful industrial AGS application in complex substrates, it is necessary to evaluate and demonstrate the technology in real industrial conditions and reduce the currently long start-up times which limits its utility. Two new strategies have been proposed: autoinducer molecules and the production of artificial granular from common active sludge with commercial alginate. Finally, the increase of research on AGS cations assimilation properties will allow a new point of view, where granules will be materials for the recovery of valuable metals from industrial wastewater streams.

In vitro cytotoxic capacity against tumor cell lines and antioxidant activity of acidic polysaccharides isolated from the Andean Patagonian fungus Phylloporia boldo.

Fungal polysaccharides possess a broad biological activity, including cytotoxic and antioxidant activities. This work aimed to evaluate the cytotoxic and antioxidant activity of the acidic polysaccharides of Phylloporia boldo strain (named PBAP40). Cytotoxic activity of polysaccharide was evaluated determining the viability of three tumor cell lines by MTT assay. The effect of acidic polysaccharide on the cell cycle of HL-60 cell line was evaluated by flow cytometry, and the antioxidant activity was determined by DPPH and ABTS assays. PBAP40 showed cytotoxic effects in tumor cell lines. Results suggest that P. boldo acidic polysaccharides arrested tumor cells in the cell cycle Sub G1 phase. The acidic polysaccharides of PBAP40 strain were not cytotoxic for the non-tumor cell line. PBAP40 also showed excellent antioxidant activity. The FT-IR analysis of the acidic polysaccharides indicated the presence of glucans bearing α- and ß- type glycosidic bonds.

Self-efficacy among health professionals to manage therapeutic groups of patients with obesity: Scale development and validity evidences.

Health professionals have to be confident to manage therapeutic groups of patients with obesity considering the potential of such approach to organize and provide health care. This study aimed to validate the scale of self-efficacy among health professionals to manage therapeutic groups of patients with obesity. Items were developed by an interprofessional group based on theoretical references on humanized healthcare. Scope, relevance, clarity, and comprehensibility of items and response options were evaluated by experts and health professionals. Using factor analysis and item response theory analysis, items with better discrimination were selected. The interpretation of the scores was proposed with a description of the self-efficacy around different levels. All steps were conducted using online forms. A pool of 21 items was proposed with up to five response options. Experts and health professionals retained 17 items with few changes in wording and four response options. The final scale was composed of 17 items, from which we derived three levels of self-efficacy (low, moderate, high). This study conceived a simple tool to assess health professionals' confidence in managing obesity in therapeutic groups, which may be helpful in designing and measuring the impact of interprofessional education programs to leverage health assistance quality.

Selenium Nanoparticle-Enriched and Potential Probiotic, Lactiplantibacillus plantarum S14 Strain, a Diet Supplement Beneficial for Rainbow Trout.

Lactic acid bacteria (LAB), obtained from rainbow trout (Oncorhynchus mykiss) intestine, were cultured in MRS medium and probiotic candidates. Concurrently, producers of elemental selenium nanoparticles (Se0Nps) were selected. Probiotic candidates were subjected to morphological characterization and the following tests: antibacterial activity, antibiotic susceptibility, hemolytic activity, catalase, hydrophobicity, viability at low pH, and tolerance to bile salts. Two LAB strains (S4 and S14) satisfied the characteristics of potential probiotics, but only strain S14 reduced selenite to biosynthesize Se0Nps. S14 strain was identified, by 16S rDNA analysis, as Lactiplantibacillus plantarum. Electron microscopy showed Se0Nps on the surface of S14 cells. Rainbow trout diet was supplemented (108 CFU g-1 feed) with Se0Nps-enriched L. plantarum S14 (LABS14-Se0Nps) or L. plantarum S14 alone (LABS14) for 30 days. At days 0, 15, and 30, samples (blood, liver, and dorsal muscle) were obtained from both groups, plus controls lacking diet supplementation. Fish receiving LABS14-Se0Nps for 30 days improved respiratory burst and plasmatic lysozyme, (innate immune response) and glutathione peroxidase (GPX) (oxidative status) activities and productive parameters when compared to controls. The same parameters also improved when compared to fish receiving LABS14, but significant only for plasmatic and muscle GPX. Therefore, Se0Nps-enriched L. plantarum S14 may be a promising alternative for rainbow trout nutritional supplementation.

Associação de doença de Hirschsprung e brida de Ladd em um neonato / Association of Hirschsprung's disease and Ladd's band in a newborn

Introdução: A doença de Hirschsprung, também conhecida como megacólon congênito, apresenta alterações na inervação entérica distal. Durante o período neonatal, apresenta-se através da tríade clássica de vômitos, distensão abdominal e atraso na eliminação meconial. Objetivo: Descrever quadro clínico de paciente do sexo masculino diagnosticado com megacólon congênito, brida congênita e má rotação intestinal. Comentário: Embora seja uma doença congênita, nem sempre o diagnóstico ocorre durante o período neonatal, devendo ser cogitada no raciocínio diagnóstico de pacientes mais velhos com história de constipação refratária ao tratamento. Aproximadamente 20% das crianças tem evolução pós-cirúrgica ruim, sendo a constipação a queixa mais comum, tendendo a melhorar com o passar dos anos. Não foi encontrado na literatura a associação de bridas congênitas, má rotação intestinal e doença de Hirschsprung. [au]

Introduction: Hirschsprung's disease, also known as congenital megacolon, presents alterations in the distal enteric innervation. During the neonatal period, it presents through the classical triad of vomiting, abdominal distension and delayed meconium elimination. Objective: To describe clinical case of a male patient diagnosed with congenital megacolon, whose initial presentation was neonatal intestinal obstruction attributed to congenital adhesion bands and intestinal malrotation and Hirschsprung's disease. Comments: Although it is a congenital disease, the diagnosis does not always occur during the neonatal period and should be considered in the diagnostic reasoning of older patients with a history of constipation refractory to treatment. Approximately 20% of children have negative outcomes on the postoperative course, with constipation being the most common complaint, tending to improve over the years. No association was found in the literature with congenital band, intestinal malrotation and Hirschsprung's disease. [au]

An Anaerobic Environment Drives the Harboring of Helicobacter pylori within Candida Yeast Cells.

Helicobacter pylori protects itself from stressful environments by forming biofilms, changing its morphology, or invading eukaryotic cells, including yeast cells. There is little knowledge about the environmental factors that influence the endosymbiotic relationship between bacterium and yeasts. Here, we studied if oxygen availability stimulated the growth of H. pylori within Candida and if this was a bacterial- or yeast strain-dependent relationship. Four H. pylori strains and four Candida strains were co-cultured in Brucella broth plus 5% fetal bovine serum, and incubated under microaerobic, anaerobic, or aerobic conditions. Bacteria-like bodies (BLBs) within yeast cells (Y-BLBs) were detected by microscopy. H. pylori was identified by FISH and by PCR amplification of the 16S rRNA gene of H. pylori from total DNA extracted from Y-BLBs from H. pylori and Candida co-cultures. BLBs viability was confirmed by SYTO-9 fluorescence. Higher Y-BLB percentages were obtained under anaerobic conditions and using H. pylori J99 and C. glabrata combinations. Thus, the H. pylori-Candida endosymbiotic relationship is strain dependent. The FISH and PCR results identified BLBs as intracellular H. pylori. Conclusion: Stressful conditions such as an anaerobic environment significantly increased H. pylori growth within yeast cells, where it remained viable, and the bacterium-yeast endosymbiotic relationship was bacterial strain dependent with a preference for C. glabrata.

Selenium Nanoparticles Biosynthesized by Pantoea agglomerans and Their Effects on Cellular and Physiological Parameters in the Rainbow Trout Oncorhynchus mykiss.

The applications of nanoparticles (Nps) as food additives, health enhancers, and antimicrobials in animal production are increasing. The aim of this study was to evaluate the effect of selenium (Se) nanoparticles (Se0Nps) stabilized with L-cysteine (Se0Nps/L-Cys), as a nutritional supplement, on immunological, oxidative status, and productive parameters in O. mykiss. TEM and SEM-EDS showed the accumulation of spherical Se0Nps entirely composed by elemental selenium (Se0) as intracellular and extracellular deposits in Pantoea agglomerans UC-32 strain. The in vitro antioxidant capacity of Se0Nps/L-Cys was significant more efficient ROS scavengers than Se0Nps and Na2SeO3. We also evaluate the effect of Se0Nps/L-Cys on cell viability and oxidative stress in RTgill-W1, RTS-11, or T-PHKM Oncorhynchus mykiss cell lines. Se0Nps/L-Cys showed less toxic and high antioxidant activity than Se0Nps and Na2SeO3. Finally, the dietary Se0Nps/L-Cys had a significant better effect on both plasma lysozyme and respiratory burst activity (innate immune response), on tissular Gpx activity (oxidative status), and on well-being (productive parameter) of O. mykiss when it is compared to Se0Nps and Na2SeO3. Se0Nps/L-Cys is a promising alternative for nutritional supplement for O. mykiss with better performance than Na2SeO3 and Se0Nps, ease to implementation, and reduced environmental impact.

Cognitive Memory Training with Healthy Elderly: Meta-Analysis and Comparison of Strategies / Treino Cognitivo de Memória com Idosos Saudáveis: Metanálise e Comparação de Estratégias

Abstract Memory training is an alternative for cognitive improvement with elderly, currently evidenced in Brazilian research. Nevertheless, there is no verification of the differences between types of training, in order to identify the effectiveness of different strategies in intervention. Therefore, this paper seeks to compare strategies adopted in the Brazilian context. A meta-analysis was carried out, evaluating the effect size, publication bias and heterogeneity of the studies. The results indicate a statistically insignificant effect from insignificant to moderate on the worked memory subsystems, although with a moderate and significant effect on incidental memory. The presence of bias in publications and high heterogeneity between studies are indicated. Subsequent meta-analyses should associate the results with methodological characteristics of the works.

Resumo O treino cognitivo é um recurso possível para o aprimoramento da memória. Este trabalho busca comparar a eficácia de estratégias de treino de memória com idosos adotadas no contexto brasileiro. Pesquisou-se por estudos que apresentassem ensaios clínicos sobre efeitos de diferentes estratégias de memorização com idosos brasileiros. Realizou-se uma metanálise do tamanho de efeito (g de Hedges) das estratégias de nove estudos que resultaram com essas características. Evidenciaram-se efeitos do treino de insignificantes a moderados, mas não estatisticamente significativos, sobre as memórias de trabalho, episódica e semântica, além de moderado e significativo sobre a memória incidental. Isso indica que estudos brasileiros têm apresentado programas de treino com estratégias de memorização com efeito no máximo moderado sobre a memória de idosos.

Gastrointestinal Microbiota and Parasite-Fauna of Wild Dissostichus eleginoides Smitt, 1898 Captured at the South-Central Coast of Chile.

Dissotichus eleginoides has a discontinuous circumpolar geographic distribution restricted to mountains and platforms, mainly in Subantarctic and Antarctic waters of the southern hemisphere, including the Southeast Pacific, Atlantic and Indian oceans and in areas surrounding the peninsular platforms of subantarctic islands. The aim of this work was to determine and characterize the gastrointestinal parasitic and microbial fauna of specimens of D. eleginoides captured in waters of the south-central zone of Chile. The magnitude of parasitism in D. eleginoides captured in waters of the south-central zone of Chile is variable, and the parasite richness is different from that reported in specimens from subantarctic environments. Next-generation sequencing (NGS) of the microbial community associated to intestine showed a high diversity, where Proteobacteria, Firmicutes, and Bacteriodetes were the dominant phyla. However, both parasitic and microbial structures can vary between fish from different geographic regions.

JAK2 and TET2 Mutation in Polycythemia Vera.

The Ten-Eleven Translocation-2 (TET2) gene, located on chromosome 4q24, has been implicated in hematological malignancies. The TET2 gene shows mutations in variable myeloid malignancies with the involvement of 15% of myeloproliferative neoplasms (MPNs). The inactivation of the TET2 gene in both mice and humans has shown a high degree of deregulation of the hematopoiesis process leading to hematological malignancies. Polycythemia vera (PV), an MPN characterized by increased red blood cell mass, has been associated with the TET2 gene. Furthermore, TET2 genes have been found to facilitate Janus kinase-2 and signal transducer activator of transcription 5, as well as modulate the epigenetic composition of genomic DNA. However, little is known about the role of TET2 mutations in patients with PV. Several studies have been conducted to further assess the significant role of TET2 gene function in various disease processes and prognoses to enhance the management and care of these patients.

Paired-Box Gene 8 (PAX8) and Its Association With Epithelial Carcinomas.

Cancer is the second most common culprit of mortality in the United States and epithelial carcinomas are considered as one of the most predominant types of cancer. The association between epithelial cancers and paired-box gene 8 (PAX8) has been studied significantly before. PAX8 belongs to the paired-box gene family, which plays an important role in the organogenesis of different body organ systems, especially the thyroid gland, the renal system, and the Müllerian system. Immunohistochemical staining is being used to detect PAX8 expression in different epithelial cancers and differentiate them from PAX8-negative tumors. In follicular, papillary, and anaplastic thyroid carcinomas, targeting the PAX8/peroxisome proliferator-activated receptors (PPARs) fusion protein is being considered as a potential mechanism for therapy. Moreover, because of its high expression in primary ovarian cancers, PAX8 is being considered as a target for ovarian cancer treatment as well. More studies are needed to test the possibility of using PAX8 as a possible target for managing endometrial carcinomas. In this article, we review the functions of the PAX8 gene, how its mutations lead to the development of certain epithelial carcinomas, how it can be used as a diagnostic or a prognostic marker, and its potential as a therapeutic target for these cancers.

The Coexistence of Chronic Obstructive Pulmonary Disease and Heart Failure.

Chronic obstructive pulmonary disease (COPD) is a chronic illness that is widely prevalent within the United States and has been frequently associated with heart failure (HF). COPD is associated with progressive damage and inflammation of the airways leading to airflow obstruction and inadequate gas exchange. HF represents a decline in the normal functioning of the heart resulting in insufficient pumping of blood through the circulatory system. COPD and HF present with similar signs and symptoms with some variation. There are many specific diagnostic tests and treatment modalities which we use to diagnose COPD and HF, but it becomes an issue when you come across a patient who has both conditions simultaneously. For example, attempting to use an X-ray to diagnose HF in a COPD patient is next to impossible because the results are manipulated by the COPD disease process. This is the case with many other diagnostic tests such as an electrocardiogram (ECG), chest radiography (X-ray), B-type natriuretic peptide (BNP), echocardiogram, cardiac magnetic resonance imaging (CMR), pulmonary function test (PFT), arterial blood gas (ABG), and exercise stress testing. When a patient has both COPD and HF, it becomes more difficult to treat. Many treatments for HF have negative impacts on COPD patients and vice-versa, whereas some have also shown positive clinical outcomes in both diseases. It is agreeable that treatment has to be patient-centered and it can vary from case to case depending on the severity of the disease. Ultimately, in this review, we discuss COPD and HF and how they interplay in their diagnostic and treatment modalities to gain a better understanding of how to effectively manage patients who have been diagnosed with both conditions.

Temperatures Outside the Optimal Range for Helicobacter pylori Increase Its Harboring within Candida Yeast Cells.

Helicobacter pylori is capable of entering into yeast, but the factors driving this endosymbiosis remain unknown. This work aimed to determine if temperatures outside the optimal range for H. pylori increase its harboring within Candida. H. pylori strains were co-cultured with Candida strains in Brucella broth supplemented with 5% fetal bovine serum and incubated at 4, 25, 37 or 40 °C. After co-culturing, yeasts containing bacteria-like bodies (Y-BLBs) were observed by optical microscopy, and the bacterium were identified as H. pylori by FISH. The H. pylori 16S rRNA gene was amplified from the total DNA of Y-BLBs. The viability of intra-yeast H. pylori cells was confirmed using a viability assay. All H. pylori strains were capable of entering into all Candida strains assayed. The higher percentages of Y-BLBs are obtained at 40 °C with any of the Candida strains. H pylori also increased its harboring within yeast in co-cultures incubated at 25 °C when compared to those incubated at 37 °C. In conclusion, although H. pylori grew significantly at 40 °C, this temperature increased its harboring within Candida. The endosymbiosis between both microorganisms is strain-dependent and permits bacterial cells to remain viable under the stressing environmental conditions assayed.

Nutrient Deficiency Promotes the Entry of Helicobacter pylori Cells into Candida Yeast Cells.

Helicobacter pylori, a Gram-negative bacterium, has as a natural niche the human gastric epithelium. This pathogen has been reported to enter into Candida yeast cells; however, factors triggering this endosymbiotic relationship remain unknown. The aim of this work was to evaluate in vitro if variations in nutrient concentration in the cultured medium trigger the internalization of H. pylori within Candida cells. We used H. pylori-Candida co-cultures in Brucella broth supplemented with 1%, 5% or 20% fetal bovine serum or in saline solution. Intra-yeast bacteria-like bodies (BLBs) were observed using optical microscopy, while intra-yeast BLBs were identified as H. pylori using FISH and PCR techniques. Intra-yeast H. pylori (BLBs) viability was confirmed using the LIVE/DEAD BacLight Bacterial Viability kit. Intra-yeast H. pylori was present in all combinations of bacteria-yeast strains co-cultured. However, the percentages of yeast cells harboring bacteria (Y-BLBs) varied according to nutrient concentrations and also were strain-dependent. In conclusion, reduced nutrients stresses H. pylori, promoting its entry into Candida cells. The starvation of both H. pylori and Candida strains reduced the percentages of Y-BLBs, suggesting that starving yeast cells may be less capable of harboring stressed H. pylori cells. Moreover, the endosymbiotic relationship between H. pylori and Candida is dependent on the strains co-cultured.

Antibiotics as a Stressing Factor Triggering the Harboring of Helicobacter pylori J99 within Candida albicans ATCC10231.

First-line treatment for Helicobacter pylori includes amoxicillin and clarithromycin or metronidazole plus a proton pump inhibitor. Treatment failure is associated with antibiotic resistance and possibly also with internalization of H. pylori into eukaryotic cells, such as yeasts. Factors triggering the entry of H. pylori into yeast are poorly understood. Therefore, the aim of this study was to evaluate whether clarithromycin or amoxicillin trigger the entry of H. pylori into C. albicans cells. METHODS: H. pylori J99 and C. albicans ATCC 10231 were co-cultured in the presence of subinhibitory concentrations of amoxicillin and clarithromycin as stressors. Bacterial-bearing yeasts were observed by fresh examination. The viability of bacteria within yeasts was evaluated, confirming the entry of bacteria into Candida, amplifying, by PCR, the H. pylori16S rRNA gene in total yeast DNA. RESULTS: Amoxicillin significantly increased the entry of H. pylori into C. albicans compared to the control. CONCLUSION: the internalization of H. pylori into C. albicans in the presence of antibiotics is dependent on the type of antibiotic used, and it suggests that a therapy including amoxicillin may stimulate the entry of the bacterium into Candida, thus negatively affecting the success of the treatment.

Characterization of Arsenite-Oxidizing Bacteria Isolated from Arsenic-Rich Sediments, Atacama Desert, Chile.

Arsenic (As), a semimetal toxic for humans, is commonly associated with serious health problems. The most common form of massive and chronic exposure to As is through consumption of contaminated drinking water. This study aimed to isolate an As resistant bacterial strain to characterize its ability to oxidize As (III) when immobilized in an activated carbon batch bioreactor and to evaluate its potential to be used in biological treatments to remediate As contaminated waters. The diversity of bacterial communities from sediments of the As-rich Camarones River, Atacama Desert, Chile, was evaluated by Illumina sequencing. Dominant taxonomic groups (>1%) isolated were affiliated with Proteobacteria and Firmicutes. A high As-resistant bacterium was selected (Pseudomonas migulae VC-19 strain) and the presence of aio gene in it was investigated. Arsenite detoxification activity by this bacterial strain was determined by HPLC/HG/AAS. Particularly when immobilized on activated carbon, P. migulae VC-19 showed high rates of As(III) conversion (100% oxidized after 36 h of incubation). To the best of our knowledge, this is the first report of a P. migulae arsenite oxidizing strain that is promising for biotechnological application in the treatment of arsenic contaminated waters.

The prediction of partial-nitrification-anammox performance in real industrial wastewater based on granular size.

To date, the partial nitrification-Anammox (PN-A) granular sludge size has been exclusively analyzed in synthetic substrates. In this work, different ranges of granular size of PN-A sludge were studied at low oxygen concentration using real industrial wastewater as, well as a synthetic substrate. The granular sludge was characterized by the specific nitrification activity (SNA), specific anammox activity (SAA), and granule sedimentation rate. The relative abundance of the bacterial consortium was assessed for each range of diameters through the fluorescence in situ hybridization (FISH) technique. SNA exhibits a direct association with the specific surface of granules, which proves the importance of the outer layer in the nitrification process. Even more critical, the flocculent sludge allowed the stability of the nitrifying activity. The SAA showed different performances faced the real industrial and synthetic substrates. With the synthetic substrate, the SAA decreased at higher diameter ranges, whereas with the industrial substrate, the SAA increased at higher diameter ranges. This situation is explained by the oxygen protection in the sludge maintained with industrial wastewater. The relative abundance of heterotrophic bacteria increased from 9.6 to 22%, due to the presence of organic matter in the industrial substrate. The granular sedimentation rate increased with the diameter of the granules with a linear correlation (R2 > 0.98). Thus, granular sizes can be selected through sedimentation rate control. A linear correlation between SAA and granular sludge diameter ranges was observed. With this correlation, an error of less than 11% in the prediction of SAA was achieved. The use of diameter measurement and granular sedimentation rate as routine techniques could contribute to the control and start-up of PN-A reactors. In the same sense, organic matter present in defined concentrations, can be beneficial for the granular sludge stability, and thus, for nitrogen removal.

Intracellular Presence of Helicobacter pylori and Its Virulence-Associated Genotypes within the Vaginal Yeast of Term Pregnant Women.

BACKGROUND: Helicobacter pylori transmission routes are not entirely elucidated. Since yeasts are postulated to transmit this pathogen, this study aimed to detect and genotype intracellular H. pylori harbored within vaginal yeast cells. METHODS: A questionnaire was used to determine risk factors of H. pylori infection. Samples were seeded on Sabouraud Dextrose Agar and horse blood-supplemented Columbia agar. Isolated yeasts were identified using and observed by optical microscopy searching for intra-yeast H. pylori. Total yeast DNA, from one random sample, was extracted to search for H. pylori virulence genes by PCR and bacterial identification by sequencing. RESULTS: 43% of samples contained yeasts, mainly Candida albicans (91%). Microscopy detected bacteria such as bodies and anti-H. pylori antibodies binding particles in 50% of the isolated yeasts. Total DNA extracted showed that 50% of the isolated yeasts were positive for H. pylori 16S rDNA and the sequence showed 99.8% similarity with H. pylori. In total, 32% of H. pylori DNA positive samples were cagA+ vacAs1a vacAm1 dupA-. No relationship was observed between possible H. pylori infection risk factors and vaginal yeasts harboring this bacterium. CONCLUSION: H. pylori having virulent genotypes were detected within vaginal yeasts constituting a risk for vertical transmission of this pathogen.

The Influence of pCO2-Driven Ocean Acidification on Open Ocean Bacterial Communities during A Short-Term Microcosm Experiment in the Eastern Tropical South Pacific (ETSP) off Northern Chile.

Due to the increasing anthropogenic CO2 emissions, Ocean Acidification (OA) is progressing rapidly around the world. Despite the major role that microorganisms play on the marine biogeochemical cycling and ecosystem functioning, the response of bacterial communities upon OA scenarios is still not well understood. Here, we have conducted a detailed characterization of the composition and relative abundance of bacterial communities in the water column of an open-ocean station in the Eastern Tropical South Pacific (ETSP) off northern Chile and their interactions with environmental factors. In addition, through a short-term microcosm experiment, we have assessed the effect of low pH/high pCO2 conditions over the abundance and genetic diversity of bacterial communities. Our results evidence a clear partitioning of community composition that could be attributed mostly to dissolved oxygen. However, our experimental approach demonstrated that low pH/high pCO2 conditions might modify the structure of the bacterial community, evidencing that small changes in pH may impact significantly the abundance and diversity of key microorganisms. This study constitutes a first step aiming to provide insight about the influence of changing carbonate chemistry conditions on natural bacterial communities and to shed light on the potential impact of OA in biogeochemical cycles on the ETSP region.