RESUMEN

BACKGROUND: Predictive microbiology is a tool that allows us to evaluate the behavior of the concentration of biomass and estimated cells under extrinsic conditions, providing scientific and industrial benefits. In the present study, the growth of L. lactis and L. casei combined with inulin and fructose was modeled using the Gompertz sigmoidal growth functions and plotted using data obtained from batch culture in relation to biomass and cell concentration expressed as estimates in ln N (OD600nm and cells mL-1 ) as a function of time. RESULTS: The results of the kinetic modeling indicated that (T1) A1B1 = L. lactis + fructose and (T4) A2B2 = L. casei + inulin presented the best function coefficients and best fits in most cases compared to the rest. The specific growth rate of the maximum acceleration was from 0.364 to 0.473 h-1 and 0.100 to 0.129 h-1 , the concentration of bacterial cells (A) was from 0.556 to 0.713 and 0.425 to 0.548 respectively and the time where (µ) occurred with a greater magnitude (L) fluctuated between 0.854 and 0.802 and when this time in (L) is very fast, it presents values of ≤0.072 to ≤0.092. Its coefficient of determination and/or multiple regression (R2 ) obtained in the two adjustments was 0.97. CONCLUSION: It was possible to predict the influence of the carbon source on the behavior of maximum growth rates, higher consumption due to nutrient affinity and shorter growth time. © 2023 Society of Chemical Industry.

Asunto(s)

Lacticaseibacillus casei , Lactococcus lactis , Prebióticos , Inulina , Fructosa , Medios de Cultivo

RESUMEN

Membrane vesicles (MVs) are envelope-derived extracellular sacs that perform a broad diversity of physiological functions in bacteria. While considerably studied in pathogenic microorganisms, the roles, relevance, and biotechnological potential of MVs from environmental bacteria are less well established. Acidithiobacillaceae family bacteria are active players in the sulfur and iron biogeochemical cycles in extremely acidic environments and drivers of the leaching of mineral ores contributing to acid rock/mine drainage (ARD/AMD) and industrial bioleaching. One key aspect of such a role is the ability of these bacteria to tightly interact with the mineral surfaces and extract electrons and nutrients to support their chemolithotrophic metabolism. Despite recent advances in the characterization of acidithiobacilli biofilms and extracellular matrix (ECM) components, our understanding of its architectural and mechanistic aspects remains scant. Using different microscopy techniques and nano-tracking analysis we show that vesiculation is a common phenomenon in distant members of the Acidithiobacillaceae family, and further explore the role of MVs in multicellular colonization behaviors using 'Fervidacidithiobacillus caldus' as a bacterial model. Production of MVs in 'F. caldus' occurred in both planktonic cultures and biofilms formed on sulfur surfaces, where MVs appeared individually or in chains resembling tube-shaped membranous structures (TSMSs) important for microbial communication. Liquid chromatography-mass spectrometry data and bioinformatic analysis of the MV-associated proteome revealed that 'F. caldus' MVs were enriched in proteins involved in cell-cell and cell-surface processes and largely typified the MVs as outer MVs (OMVs). Finally, microbiological assays showed that amendment of 'F. caldus' MVs to cells and/or biofilms affects collective colonizing behaviors relevant to the ecophysiology and applications of these acidophiles, providing grounds for their exploitation in biomining.

RESUMEN

Chronic wounds cannot heal due to impairment of regeneration, mainly caused by the persistent infection of multispecies biofilms. Still, the effects of biofilm wound infection and its interaction with the host are not fully described. We aimed to study functional biofilms in physiological conditions in vitro, and their potential effects in health and regeneration in vivo. Therefore, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis were seeded in collagen-based scaffolds for dermal regeneration. After 24 h, scaffolds had bacterial loads depending on the initial inoculum, containing viable biofilms with antibiotic tolerance. Afterwards, scaffolds were implanted onto full skin wounds in mice, together with daily supervision and antibiotic treatment. Although all mice survived their health was affected, displaying fever and weight loss. After ten days, histomorphology of scaffolds showed high heterogeneity in samples and within groups. Wounds were strongly, mildly, or not infected according to colony forming units, and P. aeruginosa had higher identification frequency. Biofilm infection induced leucocyte infiltration and elevated interferon-γ and interleukin-10 in scaffolds, increase of size and weight of spleen and high systemic pro-calcitonin concentrations. This functional and implantable 3D biofilm model allows to study host response during infection, providing a useful tool for infected wounds therapy development.

Asunto(s)

Infecciones por Pseudomonas , Infección de Heridas , Ratones , Animales , Infecciones por Pseudomonas/microbiología , Infección de Heridas/microbiología , Biopelículas , Pseudomonas aeruginosa , Staphylococcus aureus/fisiología , Antibacterianos/farmacología

RESUMEN

Bioleaching of metal sulfides is performed by diverse microorganisms. The dissolution of metal sulfides occurs via two chemical pathways, either the thiosulfate or the polysulfide pathway. These are determined by the metal sulfides' mineralogy and their acid solubility. The microbial cell enables metal sulfide dissolution via oxidation of iron(II) ions and inorganic sulfur compounds. Thereby, the metal sulfide attacking agents iron(III) ions and protons are generated. Cells are active either in a planktonic state or attached to the mineral surface, forming biofilms. This review, as an update of the previous one (Vera et al., 2013a), summarizes some recent discoveries relevant to bioleaching microorganisms, contributing to a better understanding of their lifestyle. These comprise phylogeny, chemical pathways, surface science, biochemistry of iron and sulfur metabolism, anaerobic metabolism, cell-cell communication, molecular biology, and biofilm lifestyle. Recent advances from genetic engineering applied to bioleaching microorganisms will allow in the future to better understand important aspects of their physiology, as well as to open new possibilities for synthetic biology applications of leaching microbial consortia. KEY POINTS: • Leaching of metal sulfides is strongly enhanced by microorganisms • Biofilm formation and extracellular polymer production influences bioleaching • Cell interactions in mixed bioleaching cultures are key for process optimization.

Asunto(s)

Protones , Tiosulfatos , Compuestos Férricos , Metales/metabolismo , Sulfuros/metabolismo , Hierro/metabolismo , Minerales , Azufre/metabolismo , Polímeros , Compuestos Ferrosos

RESUMEN

The oxidation of arsenic (As) is a key step in its removal from water, and biological oxidation may provide a cost-effective and sustainable method. The biofilm-formation ability of Ancylobacter sp. TS-1, a novel chemolithoautotrophic As oxidizer, was studied for four materials: polypropylene, graphite, sand, and zeolite. After seven days under batch mixotrophic conditions, with high concentrations of As(III) (225 mg·L-1), biofilm formation was detected on all materials except for polypropylene. The results demonstrate As(III)-oxidation of TS-1 biofilms and suggest that the number of active cells was similar for graphite, sand, and zeolite. However, the biofilm biomass follows the specific surface area of each material: 7.0, 2.4, and 0.4 mg VSS·cm-3 for zeolite, sand, and graphite, respectively. Therefore, the observed biofilm-biomass differences were probably associated with different amounts of EPS and inert biomass. Lastly, As(III)-oxidation kinetics were assessed for the biofilms formed on graphite and zeolite under chemolithoautotrophic conditions. The normalized oxidation rate for biofilms formed on these materials was 3.6 and 1.0 mg·L-1·h-1·cm-3, resulting among the highest reported values for As(III)-oxidizing biofilms operated at high-As(III) concentrations. Our findings suggest that biofilm reactors based on Ancylobacter sp. TS-1 are highly promising for their utilization in As(III)-oxidation pre-treatment of high-As(III) polluted waters.

Asunto(s)

Arsénico , Biopelículas , Oxidación-Reducción , Silicatos , Titanio

RESUMEN

Acidithiobacillus species are fundamental players in biofilm formation by acidophile bioleaching communities. It has been previously reported that Acidithiobacillus ferrooxidans possesses a functional quorum sensing mediated by acyl-homoserine lactones (AHL), involved in biofilm formation, and AHLs naturally produced by Acidithiobacillus species also induce biofilm formation in Acidithiobacillus thiooxidans. A c-di-GMP pathway has been characterized in Acidithiobacillus species but it has been pointed out that the c-di-GMP effector PelD and pel-like operon are only present in the sulfur oxidizers such as A. thiooxidans. PEL exopolysaccharide has been recently involved in biofilm formation in this Acidithiobacillus species. Here, by comparing wild type and ΔpelD strains through mechanical analysis of biofilm-cells detachment, fluorescence microscopy and qPCR experiments, the structural role of PEL exopolysaccharide and the molecular network involved for its biosynthesis by A. thiooxidans were tackled. Besides, the effect of AHLs on PEL exopolysaccharide production was assessed. Mechanical resistance experiments indicated that the loss of PEL exopolysaccharide produces fragile A. thiooxidans biofilms. qRT-PCR analysis established that AHLs induce the transcription of pelA and pelD genes while epifluorescence microscopy studies revealed that PEL exopolysaccharide was required for the development of AHL-induced biofilms. Altogether these results reveal for the first time that AHLs positively regulate pel genes and participate in the molecular network for PEL exopolysaccharide biosynthesis by A. thiooxidans.

Asunto(s)

Acidithiobacillus thiooxidans/genética , Acil-Butirolactonas/metabolismo , Extremófilos/genética , Regulación Bacteriana de la Expresión Génica , Polisacárido Liasas/genética , Acidithiobacillus thiooxidans/metabolismo , Biopelículas/crecimiento & desarrollo , Vías Biosintéticas/genética , GMP Cíclico/análogos & derivados , GMP Cíclico/metabolismo , Extremófilos/metabolismo , Operón , Polisacárido Liasas/metabolismo , Polisacáridos Bacterianos/biosíntesis , Percepción de Quorum

RESUMEN

The family Acidiferrobacteraceae (order Acidiferrobacterales) currently contains Gram negative, neutrophilic sulfur oxidizers such as Sulfuricaulis and Sulfurifustis, as well as acidophilic iron and sulfur oxidizers belonging to the Acidiferrobacter genus. The diversity and taxonomy of the genus Acidiferrobacter has remained poorly explored. Although several metagenome and bioleaching studies have identified its presence worldwide, only two strains, namely Acidiferrobacter thiooxydans DSM 2932T, and Acidiferrobacter spp. SP3/III have been isolated and made publically available. Using 16S rRNA sequence data publically available for the Acidiferrobacteraceae, we herein shed light into the molecular taxonomy of this family. Results obtained support the presence of three clades Acidiferrobacter, Sulfuricaulis and Sulfurifustis. Genomic analyses of the genome sequences of A. thiooxydansT and Acidiferrobacter spp. SP3/III indicate that ANI relatedness between the SPIII/3 strain and A. thiooxydansT is below 95-96%, supporting the classification of strain SP3/III as a new species within this genus. In addition, approximately 70% of Acidiferrobacter sp. SPIII/3 predicted genes have a conserved ortholog in A. thiooxydans strains. A comparative analysis of iron, sulfur oxidation pathways, genome plasticity and cell-cell communication mechanisms of Acidiferrobacter spp. are also discussed.

Asunto(s)

Gammaproteobacteria/genética , Genoma Bacteriano , ADN Bacteriano/genética , Gammaproteobacteria/clasificación , Gammaproteobacteria/aislamiento & purificación , Gammaproteobacteria/metabolismo , Genómica , Hierro/metabolismo , Filogenia , ARN Ribosómico 16S/genética , Azufre/metabolismo

RESUMEN

The understanding of biofilm formation by bioleaching microorganisms is of great importance for influencing mineral dissolution rates and to prevent acid mine drainage (AMD). Thermo-acidophilic archaea such as Acidianus, Sulfolobus and Metallosphaera are of special interest due to their ability to perform leaching at high temperatures, thereby enhancing leaching rates. In this work, leaching experiments and visualization by microscopy of cell attachment and biofilm formation patterns of the crenarchaeotes Sulfolobus metallicus DSM 6482(T) and the Acidianus isolates DSM 29038 and DSM 29099 in pure and mixed cultures on sulfur or pyrite were studied. Confocal laser scanning microscopy (CLSM) combined with fluorescent dyes as well as fluorescently labeled lectins were used to visualize different components (e.g. DNA, proteins or glycoconjugates) of the aforementioned species. The data indicate that cell attachment and the subsequently formed biofilms were species- and substrate-dependent. Pyrite leaching experiments coupled with pre-colonization and further inoculation with a second species suggest that both species may negatively influence each other during pyrite leaching with respect to initial attachment and pyrite dissolution rates. In addition, the investigation of binary biofilms on pyrite showed that both species were heterogeneously distributed on pyrite surfaces in the form of individual cells or microcolonies. Physical contact between the two species seems to occur, as revealed by specific lectins able to specifically bind single species within mixed cultures.

Asunto(s)

Acidianus/fisiología , Biopelículas/crecimiento & desarrollo , Microbiología Ambiental , Interacciones Microbianas , Sulfolobus/fisiología , Adhesión Bacteriana , Hierro/metabolismo , Microscopía Confocal , Sulfuros/metabolismo , Azufre/metabolismo

RESUMEN

OBJECTIVE: To determine the family type, family structure in a group of patients with a diagnosis of substance abuse or dependence who were at a rehabilitation center for addiction during the period between August and October 2009. METHODS: Through a descriptive qualitative-interpretative methodology 10 patients who met inclusion criteria for substance dependence or abuse were studied. The fieldwork and transcripts were made for three months by non-participant observation, non-structured interviews and examination of patients' clinical history. RESULTS: Seven of the families interviewed were single-parent families with an unconventional organization on "gender roles". Single-parent families favored loneliness, difficulty in rule-setting, de-idealization of the place of the father in the family structure and a constant search for complicity. In the analysis by categories, we found that in 10 families in the study of individuals with addictions it is common to find family structure characteristics such as inadequate communication, lack of authority rules and limits, presence of triangulations, the lack of cohesion due to the existence of a disconnected relationship pattern and changed roles compared to conventional gender. The search for the affection of the mother at her emotional overload absence of roles and lack of father, raised by the separation of the couple, was found as an essential aspect underlying the addictive behavior. A pattern of parental abandonment is configured. CONCLUSION: The findings confirmed what has been mentioned by various authors regarding the characteristics of the family typology structure and personal factors in patients with addictions, in addition to their need for affection combined with the desire for the mother's presence. The family typology does not determine for itself the abuse of psychoactive substances, but the influence of other factors such as family structure, especially deficient affective interactions, which should be considered in the development of therapeutic strategies.

Asunto(s)

Niño Abandonado , Composición Familiar , Centros de Tratamiento de Abuso de Sustancias , Trastornos Relacionados con Sustancias/epidemiología , Adolescente , Adulto , Colombia , Femenino , Humanos , Masculino , Persona de Mediana Edad , Trastornos Relacionados con Sustancias/rehabilitación , Adulto Joven

RESUMEN

Bioleaching corresponds to the microbial-catalyzed process of conversion of insoluble metals into soluble forms. As an applied biotechnology globally used, it represents an extremely interesting field of research where omics techniques can be applied in terms of knowledge development, but moreover in terms of process design, control, and optimization. In this mini-review, the current state of genomics, proteomics, and metabolomics of bioleaching and the major impacts of these analytical methods at industrial scale are highlighted. In summary, genomics has been essential in the determination of the biodiversity of leaching processes and for development of conceptual and functional metabolic models. Proteomic impacts are mostly related to microbe-mineral interaction analysis, including copper resistance and biofilm formation. Early steps of metabolomics in the field of bioleaching have shown a significant potential for the use of metabolites as industrial biomarkers. Development directions are given in order to enhance the future impacts of the omics in biohydrometallurgy.

Asunto(s)

Biotecnología/métodos , Microbiología Industrial/métodos , Minerales/metabolismo , Genómica/métodos , Redes y Vías Metabólicas , Metabolómica/métodos , Proteómica/métodos

RESUMEN

Objetivo: Determinar la estructura y la tipología familiar de un grupo de pacientes con dependencia o abuso de sustancias que se encontraban en un centro de rehabilitación de adicciones durante el periodo comprendido entre agosto y octubre de 2009. Métodos: A través de una metodología descriptiva cualitativa-interpretativa, se estudió a 10 pacientes y sus familias que cumplían los criterios de inclusión por dependencia o abuso de sustancias; el trabajo de campo y las transcripciones se realizaron durante 3 meses mediante observación no participante, entrevista no estructurada y revisión de la historia clínica del paciente. Resultados: De las familias entrevistadas, siete eran monoparentales, con una organización no convencional respecto a «roles de género¼. La familia monoparental favorece la soledad, la dificultad para poner reglas, la desidealización del lugar del padre en la estructura familiar y la búsqueda de una complicidad constante. En el análisis por categorías, se concluyó que en las 10 familias del estudio de personas con adicciones son frecuentes características de la estructura familiar como la comunicación inadecuada, la ausencia de autoridad, reglas y límites, la presencia de triangulaciones, la falta de cohesión dada por la existencia de un patrón de relación desligado y el cambio de roles convencionales con respecto a género. La búsqueda del afecto de la madre ante su ausencia emocional por la sobrecarga en los roles y la falta del padre, suscitada por la separación de la pareja, se encontró como un aspecto esencial subyacente al comportamiento adictivo. Se configura un patrón de abandono parental. Conclusiones: Se confirma lo mencionado por diversos autores acerca de las características de la tipología y la estructura familiar encontradas en pacientes con adicciones, además de su necesidad de afecto junto con la premura por una figura maternal. La tipología familiar no determina por sí misma el abuso de sustancias psicoactivas, sino la influencia de otros factores como la estructura familiar, especialmente las interacciones afectivas deficientes, lo cual debe considerarse en el desarrollo de las estrategias terapéuticas.

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Objective: To determine the family type, family structure in a group of patients with a diagnosis of substance abuse or dependence who were at a rehabilitation center for addiction during the period between August and October 2009. Methods: Through a descriptive qualitative-interpretative methodology 10 patients who met inclusion criteria for substance dependence or abuse were studied. The fieldwork and transcripts were made for three months by non-participant observation, non-structured interviews and examination of patients' clinical history. Results: Seven of the families interviewed were single-parent families with an unconventional organization on "gender roles". Single-parent families favored loneliness, difficulty in rule-setting, de-idealization of the place of the father in the family structure and a constant search for complicity. In the analysis by categories, we found that in 10 families in the study of individuals with addictions it is common to find family structure characteristics such as inadequate communication, lack of authority rules and limits, presence of triangulations, the lack of cohesion due to the existence of a disconnected relationship pattern and changed roles compared to conventional gender. The search for the affection of the mother at her emotional overload absence of roles and lack of father, raised by the separation of the couple, was found as an essential aspect underlying the addictive behavior. A pattern of parental abandonment is configured. Conclusion: The findings confirmed what has been mentioned by various authors regarding the characteristics of the family typology structure and personal factors in patients with addictions, in addition to their need for affection combined with the desire for the mother's presence. The family typology does not determine for itself the abuse of psychoactive substances, but the influence of other factors such as family structure, especially deficient affective interactions, which should be considered in the development of therapeutic strategies.

Asunto(s)

Humanos , Masculino , Femenino , Adolescente , Adulto , Persona de Mediana Edad , Centros de Rehabilitación , Familia , Trastornos Relacionados con Sustancias , Terapéutica , Conducta Adictiva , Afecto , Familia Monoparental , Padre , Identidad de Género , Madres

RESUMEN

Microorganisms are used to aid the extraction of valuable metals from low-grade sulfide ores in mines worldwide, but relatively little is known about this process in cold environments. This study comprises a preliminary analysis of the bacterial diversity of the polyextremophilic acid River Aroma located in the Chilean Altiplano, and revealed that Betaproteobacteria was the most dominant bacterial group (Gallionella-like and Thiobacillus-like). Taxa characteristic of leaching environments, such Acidithiobacillus and Leptospirillum, were detected at low abundances. Also, bacteria not associated with extremely acidic, metal-rich environments were found. After enrichment in iron- and sulfur-oxidizing media, we isolated and identified a novel psychrotolerant Acidithiobacillus ferrivorans strain ACH. This strain can grow using ferrous iron, sulfur, thiosulfate, tetrathionate and pyrite, as energy sources. Optimal growth was observed in the presence of pyrite, where cultures reached a cell number of 6.5 · 10(7) cells mL(-1). Planktonic cells grown with pyrite showed the presence of extracellular polymeric substances (10 °C and 28 °C), and a high density of cells attached to pyrite grains were observed at 10 °C by electron microscopy. The attachment of cells to pyrite coupons and the presence of capsular polysaccharides were visualized by using epifluorescence microscopy, through nucleic acid and lectin staining with Syto(®)9 and TRITC-Con A, respectively. Interestingly, we observed high cell adhesion including the formation of microcolonies within 21 days of incubation at 4 °C, which was correlated with a clear induction of capsular polysaccharides production. Our data suggests that attachment to pyrite is not temperature-dependent in At. ferrivorans ACH. The results of this study highlight the potential of this novel psychrotolerant strain in oxidation and attachment to minerals under low-temperature conditions.

Asunto(s)

Acidithiobacillus/aislamiento & purificación , Acidithiobacillus/metabolismo , Acidithiobacillus/fisiología , Biopelículas/crecimiento & desarrollo , Microbiología Ambiental , Hierro/metabolismo , Sulfuros/metabolismo , Adhesión Bacteriana , Chile , Análisis por Conglomerados , Frío , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Compuestos Inorgánicos/metabolismo , Microscopía Electrónica de Transmisión , Microscopía Fluorescente , Datos de Secuencia Molecular , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN

RESUMEN

Biofilm formation plays a pivotal role in bioleaching activities of bacteria in both industrial and natural environments. Here, by visualizing attached bacterial cells on energetic substrates with different microscopy techniques, we obtained the first direct evidence that it is possible to positively modulate biofilm formation of the extremophilic bacterium Acidithiobacillus ferrooxidans on sulfur and pyrite surfaces by using Quorum Sensing molecules of the N-acylhomoserine lactone type (AHLs). Our results revealed that AHL-signaling molecules with a long acyl chain (12 or 14 carbons) increased the adhesion of A. ferrooxidans cells to these substrates. In addition, Card-Fish experiments demonstrated that C14-AHL improved the adhesion of indigenous A. ferrooxidans cells from a mixed bioleaching community to pyrite. Finally, we demonstrated that this improvement of cell adhesion is correlated with an increased production of extracellular polymeric substances. Our results open up a promising means to develop new strategies for the improvement of bioleaching efficiency and metal recovery, which could also be used to control environmental damage caused by acid mine/rock drainage.

Asunto(s)

Acidithiobacillus/fisiología , Acil-Butirolactonas/metabolismo , Biopelículas/crecimiento & desarrollo , Hierro/metabolismo , Metales/metabolismo , Percepción de Quorum/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Sulfuros/metabolismo , Acidithiobacillus/efectos de los fármacos , Adhesión Bacteriana , Polímeros/metabolismo , Azufre/metabolismo

RESUMEN

The chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans is of great importance in biomining operations. During the bioleaching of ores, microorganisms are subjected to a variety of environmental stresses and to the limitations of some nutrients, such as inorganic phosphate (P(i)), which is an essential component for all living cells. Although the primary source of phosphorus for microorganisms is P(i), some bacteria are also able to metabolize P(i) esters (with a C-O-P bond) and phosphonates (with a very inert C-P bond). By using bioinformatic analysis of genomic sequences of the type strain of A. ferrooxidans (ATCC 23270), we found that as part of a Pho regulon, this bacterium has a complete gene cluster encoding C-P lyase, which is the main bacterial enzyme involved in phosphonate (Pn) degradation in other microorganisms. A. ferrooxidans was able to grow in the presence of methyl-Pn or ethyl-Pn as an alternative phosphorus source. Under these growth conditions, a great reduction in inorganic polyphosphate (polyP) levels was seen compared with the level for cells grown in the presence of P(i). By means of reverse transcription-PCR (RT-PCR), DNA macroarrays, and real-time RT-PCR experiments, it was found that A. ferrooxidans phn genes were cotranscribed and their expression was induced when the microorganism was grown in methyl-Pn as the only phosphorus source. This is the first report of phosphonate utilization in a chemolithoautotrophic microorganism. The existence of a functional C-P lyase system is a clear advantage for the survival under P(i) limitation, a condition that may greatly affect the bioleaching of ores.

Asunto(s)

Acidithiobacillus/genética , Liasas/genética , Operón , Organofosfonatos/metabolismo , Fosfatos/metabolismo , Acidithiobacillus/crecimiento & desarrollo , Acidithiobacillus/metabolismo , Regulación Bacteriana de la Expresión Génica , Genes Bacterianos , Liasas/metabolismo , Viabilidad Microbiana/genética , Modelos Genéticos , Análisis de Secuencia por Matrices de Oligonucleótidos , Regulón/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa

RESUMEN

OBJECTIVES: The objectives of this study were to determine the prevalence of sexually transmitted infection (STIs) in heterosexual couples and the sexual behaviors associated with their acquisition. GOAL: The goal of this study was to better direct educational efforts to decrease STI among heterosexual couples in Lima, Peru. STUDY DESIGN: We conducted a case-control study in 195 heterosexual couples without HIV infection who attended 2 sexually transmitted disease clinics in Lima, Peru. A case was defined as an individual with one or more newly diagnosed STIs such as gonorrhea, chlamydia, trichomoniasis, herpes simplex, syphilis, mycoplasma, or ureaplasma. RESULTS: Thirty-three percent of individuals (41 men and 89 women) had at least one STI and 26 couples (13%) had the same STI detected. Men who have sex with men (MSM) accounted for 13% of all men, had higher rate of STIs and higher risk behaviors than non-MSM. Ureaplasma infection was the most prevalent STI found in both men and women and was associated with oral sexual contact. In heterosexual pairs, condom use during anal sex occurred less than 10% of the time. CONCLUSIONS: The heterosexual couples in sexually transmitted disease clinics have high-risk behaviors and STIs are frequent. The educational effort concerning prevention of STIs requires higher effort.

Asunto(s)

Asunción de Riesgos , Conducta Sexual , Enfermedades de Transmisión Sexual/epidemiología , Enfermedades de Transmisión Sexual/prevención & control , Adolescente , Adulto , Instituciones de Atención Ambulatoria , Femenino , Humanos , Masculino , Persona de Mediana Edad , Perú/epidemiología , Prevalencia , Factores de Riesgo , Enfermedades de Transmisión Sexual/etiología

RESUMEN

Acidithiobacillus ferrooxidans is one of the main acidophilic chemolithotrophic bacteria involved in the bioleaching of metal sulfide ores. The bacterium-mineral interaction requires the development of biofilms, whose formation is regulated in many microorganisms by type AI-1 quorum sensing. Here, we report the existence and characterization of a functional type AI-1 quorum-sensing system in A. ferrooxidans. This microorganism produced mainly acyl-homoserine lactones (AHL) with medium and large acyl chains and different C-3 substitutions, including 3-hydroxy-C8-AHL, 3-hydroxy-C10-AHL, C12-AHL, 3-oxo-C12-AHL, 3-hydroxy-C12-AHL, C14-AHL, 3-oxo-C14-AHL, 3-hydroxy-C14-AHL, and 3-hydroxy-C16-AHL. A quorum-sensing genetic locus that includes two open reading frames, afeI and afeR, which have opposite orientations and code for proteins with high levels of similarity to members of the acyl synthase (I) and transcriptional regulator (R) protein families, respectively, was identified. Overexpression of AfeI in Escherichia coli and the associated synthesis of AHLs confirmed that AfeI is an AHL synthase. As determined by reverse transcription-PCR, the afeI and afeR genes were transcribed in A. ferrooxidans. The transcription levels of the afeI gene were higher in cells grown in sulfur and thiosulfate media than in iron-grown cells. Phosphate starvation induced an increase in the transcription levels of afeI which correlated with an increase in AHL levels. Two afe boxes which could correspond to the AfeR binding sites were identified upstream of the afeI gene. This is the first report of a functional type AI-1 quorum-sensing system in an acidophilic chemolithotrophic microorganism, and our results provide a very interesting opportunity to explore the control and regulation of biofilm formation during the bioleaching process.

Asunto(s)

4-Butirolactona/análogos & derivados , Acidithiobacillus/crecimiento & desarrollo , Proteínas Bacterianas/metabolismo , Regulación Bacteriana de la Expresión Génica , Ligasas/metabolismo , 4-Butirolactona/genética , 4-Butirolactona/metabolismo , Acidithiobacillus/metabolismo , Secuencia de Aminoácidos , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Medios de Cultivo , Concentración de Iones de Hidrógeno , Ligasas/química , Ligasas/genética , Modelos Moleculares , Datos de Secuencia Molecular , Fosfatos/metabolismo

RESUMEN

Eight nucleotide sequences containing a single rhodanese domain were found in the Acidithiobacillus ferrooxidans ATCC 23270 genome: p11, p14, p14.3, p15, p16, p16.2, p21, and p28. Amino acids sequence comparisons allowed us to identify the potentially catalytic Cys residues and other highly conserved rhodanese family features in all eight proteins. The genomic contexts of some of the rhodanese-like genes and the determination of their expression at the mRNA level by using macroarrays suggested their implication in sulfur oxidation and metabolism, formation of Fe-S clusters or detoxification mechanisms. Several of the putative rhodanese genes were successfully isolated, cloned and overexpressed in E. coli and their thiosulfate:cyanide sulfurtransferase (TST) and 3-mercaptopyruvate/cyanide sulfurtransferase (MST) activities were determined. Based on their sulfurtransferase activities and on structural comparisons of catalytic sites and electrostatic potentials between homology- modeled A. ferrooxidans rhodaneses and the reported crystal structures of E. coli GlpE (TST) and SseA (MST) proteins, two of the rhodanese-like proteins (P15 and P16.2) could clearly be defined as TSTs, and P14 and P16 could possibly correspond to MSTs. Nevertheless, several of the eight A. ferrooxidans rhodanese-like proteins may have some different functional activities yet to be discovered.

Asunto(s)

Acidithiobacillus/enzimología , Acidithiobacillus/genética , Genoma Bacteriano , Sulfotransferasas/genética , Secuencia de Aminoácidos , Sitios de Unión , Dominio Catalítico , Sistema Libre de Células , Clonación Molecular , Biología Computacional , Cristalografía por Rayos X , Cianuros/metabolismo , Cisteína/análogos & derivados , Cisteína/química , Cisteína/metabolismo , Cartilla de ADN/química , Escherichia coli/metabolismo , Proteínas Hierro-Azufre/química , Modelos Genéticos , Modelos Moleculares , Datos de Secuencia Molecular , Análisis de Secuencia por Matrices de Oligonucleótidos , Sistemas de Lectura Abierta , Oxígeno/química , Reacción en Cadena de la Polimerasa , ARN Mensajero/metabolismo , Homología de Secuencia de Aminoácido , Especificidad de la Especie , Electricidad Estática , Tiosulfato Azufretransferasa/genética , Tiosulfato Azufretransferasa/metabolismo , Tiosulfatos/metabolismo

Asunto(s)

Aprendizaje , Bolivia , Cambio Social , Desarrollo Humano , Participación de la Comunidad , Pobreza

RESUMEN

La preocupación actual sobre el incremento de la pobreza ha derivado en el uso de nuevos terminos que van desde el desarrollo economico con equidad, exclusivo, social, enfoque de genero, neoliberalismo, globalización, hasta desarrollo humano, mientras los pilares del esenario que la sostienen y perpetuan la pobreza permanecen incolumnes e incomprendidos...

Asunto(s)

Pobreza , Áreas de Pobreza , Bolivia