Exploring the potential of the halotolerant bacterial strain Bacillus subtilis LN8B as an ecofriendly sulfide collector for seawater flotation.

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 ∼39.3% ± 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.

Molecular diagnostic approaches for SARS-CoV-2 detection and pathophysiological consequences.

SARS-CoV-2, a novel coronavirus within the Coronaviridae family, is the causative agent behind the respiratory ailment referred to as COVID-19. Operating on a global scale, COVID-19 has led to a substantial number of fatalities, exerting profound effects on both public health and the global economy. The most frequently reported symptoms encompass fever, cough, muscle or body aches, loss of taste or smell, headaches, and fatigue. Furthermore, a subset of individuals may manifest more severe symptoms, including those consistent with viral pneumonitis, which can be so profound as to result in fatalities. Consequently, this situation has spurred the rapid advancement of disease diagnostic technologies worldwide. Predominantly employed in diagnosing COVID-19, the real-time quantitative reverse transcription PCR has been the foremost diagnostic method, effectively detecting SARS-CoV-2 viral RNA. As the pandemic has evolved, antigen and serological tests have emerged as valuable diagnostic tools. Antigen tests pinpoint specific viral proteins of SARS-CoV-2, offering swift results, while serological tests identify the presence of antibodies in blood samples. Additionally, there have been notable strides in sample collection methods, notably with the introduction of saliva-based tests, presenting a non-invasive substitute to nasopharyngeal swabs. Given the ongoing mutations in SARS-CoV-2, there has been a continuous need for genomic surveillance, encompassing full genome sequencing and the identification of new variants through Illumina technology and, more recently, nanopore metagenomic sequencing (SMTN). Consequently, while diagnostic testing methods for COVID-19 have experienced remarkable progress, no test is flawless, and there exist limitations with each technique, including sensitivity, specificity, sample collection, and the minimum viral load necessary for accurate detection. These aspects are comprehensively addressed within this current review.

The microbial world in copper sulfide flotation plants (CSFP): Novel insights into bacterial communities and their application as potential pyrite bioreagents.

Operations in copper sulfide flotation plants (CSFP) are complex and governed by several variables such as available technologies, reagents, and environmental conditions. However, few investigations are related to studying the microbial communities. These aspects provide a reason to compare the bacterial communities of two CSFP operated with freshwater (FwFlo) and seawater (SwFlo), and study whether indigenous bacteria could be used as pyrite bioreagents. Analyses were determined through next-generation sequencing by Illumina MiSeq System and conducted throughout the entire process: (i) minerals before and after grinding; (ii) final concentrate and concentrate thickener overflow; (iii) final tailings and tailings thickener overflow; and (iv) intake water. Bacterial strains from both plants were tested as potential bioreagents, given their tendency to adhere to pyrite after 5 min. In both CSFP, Proteobacteria (relative abundance from 45.48% to 79.22%), followed by Bacteroidetes (9.37%-44.7%), were the most abundant phyla. Regarding species, Algoriphagus olei (11.35%-43.52%) was present exclusively in FwFlo samples in contact with process water and absent in the mineral before grinding, where Cupriavidus metallidurans (16.05%) and Pseudomonas_uc (11.79%) predominated. In SwFlo samples, Marinobacter flavimaris (3.47%-41.1%), and GU061212-s (10.92%-27.63%), were the most abundant microorganisms. All of them were also detected in intake seawater. The strains with the highest adhesion rate (from 29.84% ± 0.14-100%) were phylogenetically identified as species of the genera Marinobacter, Pseudomonas, Idiomarina, Halomonas, Bacillus, Aerocuccus, and Peribacillus. Our results reveal that bacterial communities are critically dependent on process waters during mining activities, and our data depicted that indigenous bacteria could be used as potential pyrite bioreagents, evidenced by a high adhesion rate. It is thus possible to propose that different indigenous bacterial strains could be considered as new bioreagents to reduce the impact of conventional flotation reagents on health from an environment friendly perspective.

Dynamic circadian fluctuations of glycemia in patients with type 2 diabetes mellitus.

BACKGROUND: Diabetes mellitus (DM) has glucose variability that is of such relevance that the appearance of vascular complications in patients with DM has been attributed to hyperglycemic and dysglycemic events. It is known that T1D patients mainly have glycemic variability with a specific oscillatory pattern with specific circadian characteristics for each patient. However, it has not yet been determined whether an oscillation pattern represents the variability of glycemic in T2D. This is why our objective is to determine the characteristics of glycemic oscillations in T2D and generate a robust predictive model. RESULTS: Showed that glycosylated hemoglobin, glycemia, and body mass index were all higher in patients with T2D than in controls (all p < 0.05). In addition, time in hyperglycemia and euglycemia was markedly higher and lower in the T2D group (p < 0.05), without significant differences for time in hypoglycemia. Standard deviation, coefficient of variation, and total power of glycemia were significantly higher in the T2D group than Control group (all p < 0.05). The oscillatory patterns were significantly different between groups (p = 0.032): the control group was mainly distributed at 2-3 and 6 days, whereas the T2D group showed a more homogeneous distribution across 2-3-to-6 days. CONCLUSIONS: The predictive model of glycemia showed that it is possible to accurately predict hyper- and hypoglycemia events. Thus, T2D patients exhibit specific oscillatory patterns of glycemic control, which are possible to predict. These findings may help to improve the treatment of DM by considering the individual oscillatory patterns of patients.

Dynamic circadian fluctuations of glycemia in patients with type 2 diabetes mellitus

BACKGROUND: Diabetes mellitus (DM) has glucose variability that is of such relevance that the appearance of vascular complications in patients with DM has been attributed to hyperglycemic and dysglycemic events. It is known that T1D patients mainly have glycemic variability with a specific oscillatory pattern with specific circadian characteristics for each patient. However, it has not yet been determined whether an oscillation pattern represents the variability of glycemic in T2D. This is why our objective is to determine the characteristics of glycemic oscillations in T2D and generate a robust predictive model. RESULTS: Showed that glycosylated hemoglobin, glycemia, and body mass index were all higher in patients with T2D than in controls (all p < 0.05). In addition, time in hyperglycemia and euglycemia was markedly higher and lower in the T2D group (p < 0.05), without significant differences for time in hypoglycemia. Standard deviation, coefficient of variation, and total power of glycemia were significantly higher in the T2D group than Control group (all p < 0.05). The oscillatory patterns were significantly different between groups (p = 0.032): the control group was mainly distributed at 2-3 and 6 days, whereas the T2D group showed a more homogeneous distribution across 2-3-to-6 days. CONCLUSIONS: The predictive model of glycemia showed that it is possible to accurately predict hyper- and hypo-glycemia events. Thus, T2D patients exhibit specific oscillatory patterns of glycemic control, which are possible to predict. These findings may help to improve the treatment of DM by considering the individual oscillatory patterns of patients.

Bioprospecting of Ureolytic Bacteria From Laguna Salada for Biomineralization Applications.

The processes of biomineralization, mediated by ureolytic bacteria, possess a wide range of technological applications, such as the formation of biocements and remediation of water and soil environments. For this reason, the bioprospecting of new ureolytic bacteria is interesting for its application to these technologies, particularly for water treatment. This study demonstrates the isolation, selection, and identification of halotolerant ureolytic bacteria from Laguna Salada (inland from Atacama Desert) and the evaluation of their ability to precipitate calcium carbonate crystals in freshwater in the presence of calcium ions, as well as the ability to induce the precipitation of crystals from different ions present in seawater. Twenty-four halotolerant ureolytic bacteria whose molecular identification gives between 99 and 100% identity with species of the genus Bacillus, Porphyrobacter, Pseudomonas, Salinivibrio, and Halomonas were isolated. When cultivated in freshwater, urea, and calcium chloride, all species are able to biomineralize calcium carbonate in different concentrations. In seawater, the strains that biomineralize the highest concentration of calcium carbonate correspond to Bacillus subtilis and Halomonas sp. SEM-EDX and XRD analyses determined that both bacteria induce the formation of 9-33% halite (NaCl), 31-66% monohydrocalcite (CaCO3 × H2O), and 24-27% struvite (MgNH4PO4 × 6H2O). Additionally, B.subtilis induces the formation of 7% anhydrite (CaSO4). In seawater, B.subtilis and Halomonas sp. were able to precipitate both calcium (96-97%) and magnesium (63-67%) ions over 14 days of testing. Ion removal assays with B.subtilis immobilized in beads indicate a direct relationship between the urea concentration and a greater removal of ions with similar rates to free cells. These results demonstrate that the biomineralization mediated by bacterial urea hydrolysis is feasible in both freshwater and seawater, and we propose its application as a new technology in improving water quality for industrial uses.