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The mining and metallurgical industry represents one of the leading causes of environmental pollution. In this context, the optimization of mineral waste management and the efficient extraction of metals of interest becomes an imperative priority for a sustainable future. Microorganisms such as Acidithiobacillus thiooxidans have represented a sustainable and economical alternative in recent years due to their capacity for environmental remediation in bioleaching processes because of their sulfur-oxidizing capacity and sulfuric acid generation. However, its use has been limited due to the reluctance of mine operators because of the constant reproduction of the bacterial culture in suitable media and the care that this entails. In this work, the central objective was to evaluate the functional characteristics of A. thiooxidans, microencapsulated and stored at room temperature for three years in vacuum bags, using a spray drying process with gum arabic as a wall vector. Growth kinetics showed a survival of 80 ± 0.52% after this long period of storage. Also, a qualitative fluorescence technique with a 5-cyano-2-3 ditolyl tetrazolium (CTC) marker was used to determine the respiratory activity of the microorganisms as soon as it was resuspended. On the other hand, the consumption of resuspended sulfur was evaluated to corroborate the correct metabolic functioning of the bacteria, with results of up to 50% sulfur reduction in 16 days and sulfate generation of 513.85 ± 0.4387 ppm and 524.15 ± 0.567 ppm for microencapsulated and non-microencapsulated cultures, respectively. These results demonstrate the success after three years of the microencapsulation process and give guidelines for its possible application in the mining-metallurgical industry. [ABSTRACT FROM AUTHOR]

Blood is a rheologically complex suspension, in which the soluble fraction contains proteins, total cholesterol and triglycerides. The blood rheological behavior is strongly affected by the concentration of these components. This work evaluates the total cholesterol effect on the rheological behavior of Wistar rat blood by means of an in vitro study. Twenty-one rats were divided into 3 groups, each one had an assigned diet with different fat content: reference group (RG) with 3%, medium fat content group (MG) with 4.5% and high-fat content group (HG) with 6.5%; in the latter group, mixed-vegetable fat was added. From each group, intraocular representative blood samples were taken with time lapse of 15 days between each sampling followed by biochemical and hemo-rheological tests. The first analysis detected changes in total cholesterol levels, attributed to the rat metabolism, formation of adipose tissue and competition for food. The second test consisted in steady simple-shear and linear oscillatory flow. The linear viscoelastic spectra reveal that the viscous modulus is larger than the elastic modulus (Gʺ > G′), with simple-shear viscosity exhibiting shear-thinning behavior. An important finding is a pseudo-solid-like behavior at low frequencies (1 rad/s) akin to the presence of yield stresses in the high-fat content group after 30 days, revealing strong interactions between total cholesterol levels and blood cells. The hemo-rheological tests represent a promising alternative to identify pathologies present in the blood (total cholesterol, digestive problems, and diabetes). [ABSTRACT FROM AUTHOR]