Adaptively evolved Escherichia coli for improved ability of formate utilization as a carbon source in sugar???free conditions

Background: Formate converted from CO2 reduction has great potential as a sustainable feedstock for biological production of biofuels and biochemicals. Nevertheless, utilization of formate for growth and chemical production by microbial species is limited due to its toxicity or the lack of a metabolic pathway. Here, we constructed a formate assimilation pathway in Escherichia coli and applied adaptive laboratory evolution to improve formate utilization as a carbon source in sugar-free conditions. Results: The genes related to the tetrahydrofolate and serine cycles from Methylobacterium extorquens AM1 were overexpressed for formate assimilation, which was proved by the 13C-labeling experiments. The amino acids detected by GC/MS showed significant carbon labeling due to biomass production from formate. Then, 150 serial subcultures were performed to screen for evolved strains with improved ability to utilize formate. The genomes of evolved mutants were sequenced and the mutations were associated with formate dehydrogenation, folate metabolism, and biofilm formation. Last, 90 mg/L of ethanol production from formate was achieved using fed-batch cultivation without addition of sugars. Conclusion: This work demonstrates the effectiveness of the introduction of a formate assimilation pathway, combined with adaptive laboratory evolution, to achieve the utilization of formate as a carbon source. This study suggests that the constructed E. coli could serve as a strain to exploit formate and captured CO2

An electrogenic redox loop in sulfate reduction reveals a likely widespread mechanism of energy conservation

The bioenergetics of anaerobic metabolism frequently relies on redox loops performed by membrane complexes with substrate- and quinone-binding sites on opposite sides of the membrane. However, in sulfate respiration (a key process in the biogeochemical sulfur cycle), the substrate- and quinone-binding sites of the QrcABCD complex are periplasmic, and their role in energy conservation has not been elucidated. Here we show that the QrcABCD complex of Desulfovibrio vulgaris is electrogenic, as protons and electrons required for quinone reduction are extracted from opposite sides of the membrane, with a H+/e− ratio of 1. Although the complex does not act as a H+-pump, QrcD may include a conserved proton channel leading from the N-side to the P-side menaquinone pocket. Our work provides evidence of how energy is conserved during dissimilatory sulfate reduction, and suggests mechanisms behind the functions of related bacterial respiratory complexes in other bioenergetic contexts

A ética na enfermagem e sua relação com poder e organização do trabalho

Dificuldades enfrentadas no cotidiano do trabalho da enfermagem, principalmente no âmbito hospitalar, têm sido denunciadas, sem que as implicações éticas decorrentes, tanto para os trabalhadores quanto, principalmente, para os clientes estejam sendo focalizadas ou, no mínimo, suficientemente questionadas. A organização do trabalho pode constituir-se em fonte maior de sofrimento para os trabalhadores de enfermagem, estando relacionada ao exercício de poder dos diferentes atores envolvidos nas instituições de saúde, podendo provocar múltiplos problemas morais e sofrimento moral. Com o presente texto, pretende-se explicitar, por meio de reflexão crítica, algumas relações entre a organização do trabalho da enfermagem, as relações de poder aí presentes e a sua dimensão ética. Estratégias para uma atuação ética das enfermeiras e demais profissionais da equipe de enfermagem, na organização do trabalho nas instituições de saúde, apontam para a necessidade de exercício de poder dessas profissionais, moralmente fundamentadas.Difficulties faced in the nursing routine, maiwly in hospitals, have been reported without the resulting ethical implications to workers and especially to clients, been sufficiently questioned. The work workers, related to the exercise of power of different actors involved in the health institutions, which can potentially cause multiple problems and distress of ethical order. This study aims to make acritical reflection about some relations between the nursing work organization, power relations and its ethical dimension, strategies for an ethical performance of nurses and other nursing professionals in the organization of work in the healthcare institutions point to the need of these professionals exercise power in an ethical way.La dificultades enfrentadas en el cotidiano del trabajo de enfermería, en especial en hospitales han sido denunciados, sin embargo las implicancias éticas resultantes no están siendo enfocadas o por lo menos discutidas a nivel de los trabajadores ni de los clientes. La organización del trabajo puede constituirse en una mayor fruente de sufrimiento para los trabajadores de enfermería, lo cual puede provocar múltiples problemas morales y sufrimiento moral con este artículo

Estresse no cotidiano acadêmico: o olhar dos alunos de Enfermagem da Universidade Federal do Piauí Estrés en el cotidiano académico: la visión de los estudiantes de enfermería de la Universidad Federal del Piauí - Brasil Stress in the academic daily: a nursing student view from the Federal University of Piauí - Brazil

Este estudo objetivou conhecer situações geradoras de estresse vivenciadas pelos alunos do Curso de Graduação em Enfermagem da Universidade Federal do Piauí UFPI no âmbito acadêmico. A metodologia constou de estudo exploratório, qualitativo, com produção de dados por meio de entrevista semi-estruturada aplicada a 22 alunos.Os resultados possibilitaram a construção das categorias de análise: situações estressoras, sintomas do estresse e desempenho das atividades acadêmicas. Constatou-se que as situações de estresse estão presentes durante o transcorrer do curso, com relevâncias em determinados momentos, como o ingresso na universidade, o cursar da disciplina Farmacologia para Enfermagem e o cumprimento de carga horária semanal irregular em períodos específicos do curso. Constatou-se que os sintomas apresentados pelos alunos foram de aspectos fisiológico e emocional. Por fim, revelou-se que as situações de estresse repercutem de forma negativa no desempenho das atividades acadêmicas desenvolvidas pelos alunos.<br>Este estudio tubo el objetivo de conocer situaciones generadoras de estrés vivenciadas por alumnos del Curso de Graduación en Enfermaría de la Universidad Federal del Piauí (UFPI) en el ámbito académico. La metodología constató de un estudio exploratorio, cualitativo, con colecta de dados basada en entrevistas semi-estructurada a 22 alumnos. Los resultados posibilitaron la construcción de categorías de análisis: situaciones de estrés, síntomas de estrés y el desempeño de las actividades académicas. Fue constatado que las situaciones de estrés están presentes durante el transcurso del curso, con relevancia en determinados momentos, tales como el ingreso en la universidad, como el curso de Farmacología para Enfermería y carga horaria semanal irregular en períodos específicos del curso. Los síntomas presentados por alumnos fueran de aspecto fisiológico y emocional. Por fin, se concluye que las situaciones de estrés repercuten de forma negativa en el desempeño de las actividades académicas desarrolladas por alumnos.<br>This study aimed at know stress' situations lived by graduate students of nursing from Federal University of Piauí (UFPI) in the academic scope. The methodology consisted of an exploratory study, qualitative, with data collection through semistructured interview applied to 22 students. The results made possible the construction of categories of analysis: stressor situations, stress symptoms and the development of academic activities. It has been verified that stress situations are present during the course, with relevance in certain moments, such as the ingression in the university, the attending pharmacology course for nursing and irregular weekly course load in specific periods of the course. It was evidenced that the symptoms presented by the students was of physiological and emotional aspects. At last, was concluded that stress situations have a negative influence upon the development of academic activities developed by students

Flexibility of Syntrophic Enzyme Systems in Desulfovibrio Species Ensures Their Adaptation Capability to Environmental Changes

The mineralization of organic matter in anoxic environments relies on the cooperative activities of hydrogen producers and consumers obligately linked by interspecies metabolite exchange in syntrophic consortia that may include sulfate reducing species such as Desulfovibrio. To evaluate the metabolic flexibility of syntrophic Desulfovibrio to adapt to naturally fluctuating methanogenic environments, we studied Desulfovibrio alaskensis strain G20 grown in chemostats under respiratory and syntrophic conditions with alternative methanogenic partners, Methanococcus maripaludis and Methanospirillum hungatei, at different growth rates. Comparative whole-genome transcriptional analyses, complemented by G20 mutant strain growth experiments and physiological data, revealed a significant influence of both energy source availability (as controlled by dilution rate) and methanogen on the electron transfer systems, ratios of interspecies electron carriers, energy generating systems, and interspecies physical associations. A total of 68 genes were commonly differentially expressed under syntrophic versus respiratory lifestyle. Under low-energy (low-growth-rate) conditions, strain G20 further had the capacity to adapt to the metabolism of its methanogenic partners, as shown by its differing gene expression of enzymes involved in the direct metabolic interactions (e.g., periplasmic hydrogenases) and the ratio shift in electron carriers used for interspecies metabolite exchange (hydrogen/formate). A putative monomeric [Fe-Fe] hydrogenase and Hmc (high-molecular-weight-cytochrome c(3)) complex-linked reverse menaquinone (MQ) redox loop become increasingly important for the reoxidation of the lactate-/pyruvate oxidation-derived redox pair, DsrC(red) and Fd(red), relative to the Qmo-MQ-Qrc (quinone-interacting membrane-bound oxidoreductase; quinone-reducing complex) loop. Together, these data underscore the high enzymatic and metabolic adaptive flexibility that likely sustains Desulfovibrio in naturally fluctuating methanogenic environments