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Minerals have been important throughout history, but nowadays, their use has increased, as well as their extraction needs. Therefore, due to the growing demand for metals, and both the depletion of high-grade ores and their related environmental concerns, the mining industry has been forced to leave behind the past traditional techniques of metal recovery (use of inorganic acids), and adopt eco-friendlier alternatives, such as the utilization of weaker leaching agents, such as organic acids. Thus, the present review is focused on the use of microbially-produced organic acids as a promising alternative to conventional techniques in the mining industry, with emphasis on the following topics: a) the advantages and disadvantages of the use of organic acids for leaching purposes, b) the main microorganisms studied for the production of these organic acids, c) a summary of the latest reports on bioleaching as well as a comparison of the existent techniques; d) the explanation of leaching mechanisms where organic acids may be involved, to fulfill metal recovery; and, e) interactions between metallic ions and organic acids. The review of the current knowledge regarding the use of organic acids for leaching purposes seeks the visualization of relevant strategies that may be improved for metal-recovery processes, intending to develop circular economy practices that may have the potential to be implemented at an industrial scale.

The presence of colonial and solitary ciliated peritrichous protozoa was determined in a Sequencing Batch Reactor system filled with tezontle, a volcanic rock, economic, and abundant material that can be found in some parts of the world, like Mexico. The presence of these protozoa was related to the removal efficiencies of organic matter. Also, two novel staining techniques are proposed for staining both colonial and solitary peritrichous protozoa. The results show that tezontle promotes the growth of solitary and colonial ciliated peritrichous protozoa, which, once identified, could be used as indicators of the efficiency of the wastewater treatment process. Additionally, the staining techniques established in the current study allowed the precise observation of protozoan nuclei. They can represent a useful complementary methodology for identifying protozoan species present in water treatment processes, along with the already existing identification techniques. The number and variety of protozoa found in the system may be considered potential bioindicators of water quality during biological treatments.

Acidithiobacillus thiooxidans has been used in bioleaching processes, being recognized for its high metal leaching ability from industrial wastes. In the present work, the sulfur-oxidizing activity of A. thiooxidans DSM 26636, adapted to increasing concentrations of ore was assessed, finding that at 28 days with 3% (w/v) of ore sample, the culture produces high amounts of the sulfate ion (SO4−2) and sulfuric acid (H2SO4) and causes a decrease in the pH value, compared to the negative control. Also, there was observed a net removal of As, Zn, Fe, Al, Cu, and Au in concentrations of 48.23 ± 3.11, 264.02 ± 26.27, 9055.81 ± 210.39, 605.29 ± 30.26, 2158 ± 359.04, and 0.99 ± 0.37 mg/kg, respectively. Thus, the present work shows the potential of A. thiooxidans DSM 26636 to be used for the extraction of metals contained in ores, especially for those containing Cu, Zn, As, Fe, and Al.

The present study evaluates the ability of Acidithioobacillus thiooxidans DSM 26636 to grow and leach metals from industrial wastes (IW) containing different metal compositions, coded as IW-steel and IW-scrap. For this purpose, biolixiviation processes were assessed during 21 days at 30°C and 150 rpm, with 1% (w/v) of IW pulp density. Microbial growth was evaluated periodically by measuring sulfates´ production; pH and sulfuric acid concentration were also monitored, and metal bioleaching was evaluated by ICP-OES. Results showed that A. thiooxidans sulfur-oxidizing activity was higher in the presence of IW-steel. Specifically, sulfates and sulfuric acid production in IW-steel corresponded to 21,524 mg/L and 0.096 M, respectively, with a pH diminution to 1.54. In the case of IW-scrap, sulfates´ production only increased to up to 4392 mg/L at day 21, and not so significant changes were observed in pH and sulfuric acid concentration. Besides, metal removal was higher in IW-steel, being Fe > Mn > Mg ≥ Zn ≥ Cu > Cr ≥ Ni. The results obtained reinforce the fact that A. thiooxidans DSM 26636 presents an elevated potential to be employed in biotreatment processes, and that its biolixiviation efficiency strongly depends on the metal content present in the residues.

In this review, research on the use of microalgae as an option for bioremediation purposes of pharmaceutical compounds is reported and discussed thoroughly. Pharmaceuticals have been detected in water bodies around the world, attracting attention towards the increasing potential risks to humans and aquatic biota. Unfortunately, pharmaceuticals have no regulatory standards for safe disposal in many countries. Despite the advances in new analytical techniques, the current wastewater treatment facilities in many countries are ineffective to remove the whole presence of pharmaceutical compounds and their metabolites. Though new methods are substantially effective, removal rates of drugs from wastewater make the cost-effectiveness ratio a not viable option. Therefore, the necessity for investigating and developing more adequate removal treatments with a higher efficiency rate and at a lower cost is mandatory. The present review highlights the algae-based removal strategies for bioremediation purposes, considering their pathway as well as the removal rate and efficiency of the microalgae species used in assays. We have critically reviewed both application of living and non-living microalgae biomass for bioremediation purposes considering the most commonly used microalgae species. In addition, the use of modified and immobilized microalgae biomass for the removal of pharmaceutical compounds from water was discussed. Furthermore, research considering various microalgal species and their potential use to detoxify organic and inorganic toxic compounds were well evaluated in the review. Further research is required to exploit the potential use of microalgae species as an option for the bioremediation of pharmaceuticals in water.

The potential of Acidithiobacillus (Thiobacillus) genus members, namely Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans, for bioleaching purposes is known. Specifically, previous studies have shown the potential of A. thiooxidans strain DSM 26636 used in bioleaching processes to remove metals in high-metal-content matrices. All Acidithiobacillus growth-monitoring techniques available to date, including sulfate production, commonly used, present disadvantages. Thus, the current work shows a technique based on DNA quantification to evaluate the growth of A. thiooxidans DSM 26636, which is useful even in the presence of a high-metal-content residue. This proposed methodology may represent a functional complementary tool to evaluate Acidithiobacillus growth to develop biometallurgical applications.

Plastics are widely used for various applications. Once discarded, it is commonly known that they represent a high environmental threat due to their slow degradation; for this reason, there is an imminent need to replace these products with eco-friendlier ones. In the present work, four bacterial polyhydroxybutyrate (PHB) producers, two consortia, and two isolated strains were successfully recovered from the facilities of a paper-manufacturing industry. Spectroscopic studies of the biopolymers obtained from these bacteria corroborated their PHB production capabilities, ranging from 4.04 ± 0.16 to 23.82 ± 3.39 g/L. The characterization of the isolate that presented the highest production yield initially coded as E22 led to the identification of a Klebsiella pneumoniae strain, which, compared with other PHA bacterial producers reported to date, could be considered with high production potential. The strain E22 was grown in 5 different media prepared from fruit peel residues of banana, orange, papaya, watermelon, and melon, to determine its growth and PHA production capabilities in these low-cost media. The results obtained show different bacterial growth yields among the media tested, although PHB production yields and productivities were similar in all these low-cost media. Cellular accumulation of the biopolymer was higher in watermelon peel medium (8.4 × 10−10 g/CFU). These results reveal the potential of K. pneumoniae E22 for PHB production applications and establish encouraging alternatives to be broader explored regarding low-cost media that could enhance the scale-up of bacterial PHA production processes.

Spent catalysts represent an environmental concern, mainly due to their elevated metal content. Although conventional treatment methods for spent catalysts are available, they generate large volumes of potentially harmful wastes and gaseous emissions. To overcome the environmental impact, biotechnological approaches are currently being explored and developed. Thus, the current study assayed the capability of Bacillus megaterium strain MNSH1-9K-1 to remove Al, Ni, V and Ti contained in the spent catalyst coded as ECAT-TL-II. To this end, B. megaterium MNSH1-9K-1 growth and metal uptake abilities in the presence of ECAT-TL-II spent catalyst at 15% (wt/vol) pulp density were evaluated in modified Starkey medium at 37 °C and 200 rpm. The results presented here show B. megaterium resistance capability to the high-metal content residue, and its Al, V and Ni removal ability, in 1,059.15 ± 197.28 mg kg-1 of Al, 43.39 ± 24.13 mg kg-1 of V and 0.58 ± 0.00 mg kg-1 of Ni, corresponding to the 0.79%, 1.63% and 0.46% of each metal content, respectively, while no Ti removal was detected. Besides, it was observed that the sporulation process took place in B. megaterium cells in the presence of the spent catalyst. The results shown in this study suggest the potential of the strain MNSH1-9K-1 for the removal of metals contained in high-metal content residues, contributing also to the knowledge of the metal resistance and removal abilities of B. megaterium in the presence of a spent catalyst, and how morphological cell changes may be occurring while metal removal is taking place.

The present Health Crisis tests the response of modern science and medicine to finding treatment for a new COVID-19 disease. The presentation on the world stage of antivirals such as remdesivir, obeys to the continuous investigation of biologically active molecules with multiple theoretical, computational and experimental tools. Diseases such as COVID:19 remind us that research into active ingredients for therapeutic purposes should cover all available sources, such as plants. In the present work, in silico tools, specifically docking study, were used to evaluate the binding and inhibition capacity of an antiviral such as remdesivir on the NSP-12 protein of SARS-CoV, a polymerase that is key in the replication of the SARS-COV virus. The results are then compared with a docking analysis of two natural products (Alpha-Bisabolol and betalain) with SARS-CoV protein, in order to find more candidates for COVID-19 virus replication inhibitors. in addition to increasing studies that help explain the specific mechanisms of the SARs-CoV-2 virus, remembering that we will have to live with the virus for an indefinite time from now on. Finally, natural products such as betalains may have inhibitory effects of a small order but in conjunction with other synergistic active ingredients they may increase their inhibition effect on NSP-12 protein of SARS-CoV., 18 pages and 11 figures

Los catalizadores, homogéneos o heterogéneos, son ampliamente utilizados para una gran variedad de procesos industriales, con el fin de producir combustibles limpios y muchos otros productos valiosos, siendo los catalizadores agotados provenientes del hidroprocesamiento los mayores residuos sólidos de la industria de la refinería y la contribución principal a la generación de catalizadores agotados. Debido a su naturaleza peligrosa, el tratamiento y la recuperación de metales de este tipo de residuos han ganado cada vez más importancia, debido al agotamiento de los recursos naturales y a la contaminación ambiental. Aunque ya existen técnicas disponibles para estos fines, éstas generan grandes volúmenes de desechos potencialmente peligrosos y producen emisiones de gases nocivos. Por lo tanto, las técnicas biotecnológicas pueden representar una alternativa promisoria para el biotratamiento y la recuperación de metales contenidos en los catalizadores agotados. Con este fin, se han analizado diversos microorganismos, que comprenden bacterias, arqueobacterias y hongos, capacitados para facilitar la eliminación de losmetales contenidos en estoscatalizadores. En estarevisión se presenta un amplio escenario sobre los avances con respecto al manejo de los catalizadores agotados y su tratamiento tradicional, seguido de una descripción detallada sobre los enfoques microbiológicos reportados hasta la actualidad.

Previous work has demonstrated that Bacillus megaterium, besides showing an elevated resistance to heavy metals, possesses the ability to remove metals like Ni, Hg, and V from liquid media.

Spent catalysts are classified as hazardous residues of major environmental concern, mainly due to its elevated metal content. Although conventional spent catalysts treatment methods are available, they generate harmful wastes. Thus, biotechnological approaches are currently being explored to overcome the negative impacts generated by traditional treatment technologies. The present work studied the ability of Cupriavidus metallidurans CH34 to remove heavy metals contained in a spent catalyst that came from an oil refining process. To this end, C. metallidurans resistance to a spent catalyst at 1% (w/w) of pulp density was evaluated, as well as its ability for the removal of the metals contained therein. The results showed that the strain was able to remove 931.56 ± 95.38 mg/kg, and 2111 ± 251.81 of Mo and V, respectively. Considering the elevated toxic nature of spent catalysts, is imminent to develop alternative methods to treat this kind of residues in order to diminish their high metal content. Hence, the data presented here exhibit the first insights into C. metallidurans ability for Mo and V removal from a spent catalyst, and explores for the first time C. metallidurans potential to be used on spent catalysts biotreatment processes.

El incremento en la contaminacion de agua por metales pesados es considerada una situacion alarmante a nivel mundial, debido al impacto adverso que estos generan en los ecosistemas y en la salud humana. Las tecnicas convencionales para disminuir la carga d e metales presentan desventajas, como son: la incompleta remocion de los metales, la produccion de lodos toxicos y los altos costos de operacion. En contraste, los enfoques biotecnologicos representan una alternativa, ya que se consideran mas amigables con el ambiente, tienen costos de operacion menores y la eficiencia de remocion de metales es mayor cuando estos se presentan en bajas concentraciones. Anteriormente se ha demostrado que la presencia simultanea de mas de un metal puede generar efectos sinergi cos, aditivos o antagonicos, afectando asi su remocion, y tambien ha sido reportada la habilidad de B. megaterium MNSH1 - 9K - 1 para remover metales . Por ello, el objetivo del presente trabajo fue analizar las propiedades de resistencia y remocion de Ni de la cepa MNSH1 - 9K - 1 en medio liquido, asi como evaluar la variacion de dichas propiedades en presencia de Al, tambien considerado como un metal toxico comunmente encontrado en los residuos industriales . Para ello, B. megaterium fue crecida en medio LB con la adicion de Ni y/o Al en diversas concentraciones, analizandose tanto la resistencia como la capacidad de remocion de Ni, por medio de cuenta viable y Espectrometria de Emision Optica por Plasma Acoplado Inductivamentente (ICP - OES), de forma respectiva. Los resultados obtenidos sugieren fuertemente que B. megaterium MNSH1 - 9K - 1 presenta una mayor susceptibilidad a Ni que a Al, y que la remocion de Ni es promovida por la presencia de Al

Bacillus megaterium strain MNSH1-9K-1, isolated from a high-metal content site in Guanajuato, Mexico, has the intrinsic capacity to remove vanadium (V) and nickel (Ni) from a petrochemical spent catalyst, and counteract the toxic effects produced in the cell due to the presence of oxidative stress. Since knowledge of the molecular components involved in the microbial resistance to spent catalysts is scarce, this study aimed to identify the proteins potentially involved in the enhanced resistance of a B. megaterium strain, during the removal of metals contained in a spent catalyst. Thus, the current research uses a proteomic approach to investigate and evidence the differences in the molecular resistance mechanisms of two B. megaterium strains, one isolated from a mining site and a wild type strain, when both are exposed to a spent catalyst. In addition, we studied their ability to eliminate nickel (Ni), vanadium (V), aluminum (Al) and molybdenum (Mo). The data presented here may contribute to the knowledge of the molecular mechanisms involved in the resistance of B. megaterium to high metal content wastes, as well as its potential utilization for the recovery of valuable industrial metals.

Spent catalysts are considered as hazardous residues of major concern, mainly due to the simultaneous presence of several metals in elevated concentrations. Although hydrometallurgical, pyrometallurgical and chelating agent methods are available to remove and recover some metals contained in spent catalysts; these procedures generate potentially hazardous wastes and the emission of harmful gases. Thus, biotechnological treatments are currently gaining importance to avoid the negative impacts of chemical technologies. To this end, diverse microorganisms have been used to assess the removal of metals from spent catalysts, comprising bacteria, archaea and fungi, whose resistance and metal uptake capabilities differ depending on the microorganism tested. Acidophilic sulfur oxidizing bacteria have been used to investigate the biotreatment and extraction of valuable metals from spent catalysts, namely Acidithiobacillus thiooxidans and Acidithiobacillus ferroxidans, as they present the ability to produce leaching agents such as sulfuric acid and sulfur oxidation intermediates. In the present work, the ability of A. thiooxidans DSM 26636 for the bioleaching of metals contained in five different spent catalysts was assessed by growing the culture in modified Starkey mineral medium (with elemental sulfur at 1%, w/v), and 1% (w/v) pulp density of each residue for up to 21 days at 30 °C and 150 rpm. Sulfur-oxidizing activity was periodically evaluated by determining sulfate concentration in the supernatants according to the NMX-k-436-1977 method. The production of sulfuric acid was assessed in the supernatants as well, by a titration procedure using NaOH 0.5 M with bromothymol blue as acid-base indicator, and by measuring pH using a digital potentiometer. On the other hand, Inductively Coupled Plasma - Optical Emission Spectrometry was used to analyze metal removal from the five different spent catalysts by A. thiooxidans DSM 26636. Results obtained show that, as could be expected, sulfuric acid production is directly related to the diminish of pH, and also to highest metal removal efficiencies. It was observed that Al and Fe are recurrently removed from refinery spent catalysts regardless of their origin and previous usage, although these removals may vary from 9.5 ± 2.2 to 439 ± 3.9 mg/kg for Al, and from 7.13 ± 0.31 to 368.4 ± 47.8 mg/kg for Fe, depending on the spent catalyst proven. Besides, bioleaching of metals like Mg, Ni, and Si was also obtained from automotive spent catalysts, which removals were of up to 66 ± 2.2, 6.2±0.07, and 100±2.4, respectively. Hence, the data presented here exhibit the potential of A. thiooxidans DSM 26636 for the simultaneous bioleaching of metals contained in spent catalysts from diverse provenance.

Considering the progressive depletion of natural resources and the increasing environmental pollution, recovery of metals from spent catalysts has been gaining importance, as they can be an eco-friendly sour-ce of commercially valuable metals. The present study reports on the ability of three Bacillus spp. strains to remove Ni and V contained in a spent catalyst at 8% of pulp density (w/v). As modifications in the growth environment, like pH and the presence of diverse carbon sources, can cause changes in cell properties, the present study evaluated the effect of glucose presence in PHGII media on Ni and V removal from a spent catalyst. Assays were performed on PHGII liquid media, and on PHGII without glucose for 7 days. The maximum removal values obtained were 2542 mg/kg for Ni, and 3701 mg/kg for V for the isolate MV-9K-2 of Bacillus megaterium in the system, where PHGII was not added with glucose

Microbacterium liquefaciens MNSH2-PHGII-2 is a nickel–vanadium-resistant bacterium isolated from mine tailings located in Guanajuato, Mexico. In PHGII liquid media, M. liquefaciens has the ability to remove 29.5 ppm of Ni and 168.3 ppm of V. The present study reports, for the first time in M. liquefaciens, the presence of the genes nccA (Ni–Co–Cd resistance), hant (high-affinity nickel transporter), smtA, a metal-binding protein gene, and VAN2 (V resistance), which showed an increased expression under exposure to 200 ppm of Ni and 200 ppm of V during the logarithmic growth phase of the microorganism in PHGII liquid media. Data about the expression profile of genes conferring metal resistance to M. liquefaciens can improve the knowledge of those mechanisms involved in the processes of Ni–V resistance and probably in Ni–V removal processes. Based on our data, we can suggest that M. liquefaciens has the potential to be used in the biological treatment of toxic wastes with high Ni and V content.

Growth of Bacillus subtilis cells, normally adapted at Earth-normal atmospheric pressure (∼101.3 kPa), was progressively inhibited by lowering of pressure in liquid LB medium until growth essentially ceased at 2.5 kPa. Growth inhibition was immediately reversible upon return to 101.3 kPa, albeit at a slower rate. A population of B. subtilis cells was cultivated at the near-inhibitory pressure of 5 kPa for 1,000 generations, where a stepwise increase in growth was observed, as measured by the turbidity of 24-h cultures. An isolate from the 1,000-generation population was obtained that showed an increase in fitness at 5 kPa when compared to the ancestral strain or a strain obtained from a parallel population that evolved for 1,000 generations at 101.3 kPa. The results from this preliminary study have implications for understanding the ability of terrestrial microbes to grow in low-pressure environments such as Mars.

The role played by the Y-family DNA polymerases YqjH and YqjW in protecting sporulating cells of Bacillus subtilis from DNA damage was determined. The absence of either yqjH and/or yqjW not only reduced sporulation efficiency but also sensitized the sporulating cells to hydrogen peroxide, tert-butylhydroperoxide (t-BHP), mitomycin-C (M-C), and UV-C radiation. Moreover, these DNA-damaging agents increased the mutation frequency of wild-type sporulating cells to 4-azaleucine, but the production of mutants was YqjH- and YqjW-dependent. In conclusion, the results presented here indicate that YqjH/YqjW-dependent-translesion synthesis (TLS) operates in sporulating B. subtilis cells and contributes in processing spontaneous and artificially induced genetic damage, which is apparently required for an efficient sporulation process.