Identification of pH-specific protein expression responses by Campylobacter jejuni strain NCTC 11168.

In this study a data dependent acquisition label-free based proteomics approach was used to identify pH-dependent proteins that respond in a growth phase independent manner in Campylobacter jejuni reference strain NCTC 11168. NCTC 11168 was grown within its pH physiological normal growth range (pH 5.8, 7.0 and 8.0, µ = âˆ¼0.5 h-1) and exposed to pH 4.0 shock for 2 h. It was discovered that gluconate 2-dehydrogenase GdhAB, NssR-regulated globins Cgb and Ctb, cupin domain protein Cj0761, cytochrome c protein CccC (Cj0037c), and phosphate-binding transporter protein PstB all show acidic pH dependent abundance increases but are not activated by sub-lethal acid shock. Glutamate synthase (GLtBD) and the MfrABC and NapAGL respiratory complexes were induced in cells grown at pH 8.0. The response to pH stress by C. jejuni is to bolster microaerobic respiration and at pH 8.0 this is assisted by accumulation of glutamate the conversion of which could bolster fumarate respiration. The pH dependent proteins linked to growth in C. jejuni NCTC 11168 aids cellular energy conservation maximising growth rate and thus competitiveness and fitness.

Uma revisão sobre: tratamento biológico de drenagem de mina — cenário atualizado, perspectivas e recomendações de futuros trabalhos / Biological treatment of mine drainage — scenario updated, perspectives, and recommendations for future works

RESUMO Rochas contendo sulfetos metálicos podem ser oxidadas em um processo catalisado por procariotos quimiolitoautotróficos ou Fe3+. A atividade mineradora acelera esse processo ao gerar resíduos contendo sulfetos metálicos com grande superfície de contato. O lixiviado resultante, conhecido como drenagem de mina (DM), é rico em sulfato, íons hidrogênio e contaminantes químicos inorgânicos como ferro (Fe), zinco (Zn), cádmio (Cd), manganês (Mn), níquel (Ni), arsênio (As) e alumínio (Al). Para remover tais poluentes, atualmente, o principal tratamento utilizado é a adição de reagentes alcalinos. Entretanto, esse método tem limitada eficiência, alto custo e gera grandes volumes de resíduos sólidos tóxicos de relativa solubilidade. Bactérias redutoras de sulfato (BRS) podem oxidar matéria orgânica com geração de sulfeto. Algumas vias metabólicas do processo consomem H+neutralizando o pH. O sulfeto produzido pode reagir com contaminantes inorgânicos e precipitá-los, permitindo sua recuperação da fase líquida. O uso de subprodutos industriais e urbanos contendo diferentes fontes de carbono como doadores de elétrons no tratamento de DM tem sido investigado. Este artigo sumariza dados sobre as variáveis relevantes para a atividade microbiana durante o tratamento biológico de DM, analisando o atual cenário de pesquisas com fontes alternativas de carbono. Discute-se ainda novas fontes de matéria orgânica ainda não aplicadas para tratamento biológico de efluentes e que, sob aspectos de sustentabilidade, dos pontos de vista sustentável e econômico, podem ser usadas no tratamento de resíduos.

ABSTRACT Rocks containing metal sulfides be can oxidized biologically or chemically. Chemolithoautotrophics prokaryotes and Fe3+ catalyze this process. The mining activities also accelerate the process for creates metal sulphides tailings with a big contact surface. The leached formed is called Mine Drainage (MD) whose composition is rich in sulphate, hydrogen ions and inorganic chemical contaminants such as Fe, Zn, Mn, Cd, Ni, As e Al. Currently, in order to remove these pollutants, the main treatment used is the addition of alkaline reagents. However, the method has limited efficiency, high cost with input reagents and generates wide amounts of toxic solid residues with high solubility. The sulphide reducing bacterias (RSB) can oxidize organic matter generating sulphide. Some metabolic pathways consume H+ neutralizing the pH. The sulphide formed can react and precipitate inorganic pollutants, allowing their recuperation from the liquid phase. The use of industrial and urban by-products containing different carbon sources have been investigated as an electron donor in the MD treatment. The diverse microbial consortia synergic acting can present bigger efficiency in the presence of mixed carbon sources, besides lower cost in relation to the pure matter. Here will be detailed the biological treatment about which and how the variables of the system can influence the microbial activity and relevant molecules to the treatment. After is described the current situation of the research about alternative carbon sources. New carbon sources whose are a by-product of the expanding industry presenting good feature to anaerobic degrading are suggested. The by-product potential is described from the point of view of sustainability, and waste management.

Global and local charge transfer in electron donor-acceptor complexes.

The formation of electron donor-acceptor complexes is studied with global and local charge transfer partitionings. The 1-parabola model is applied to the bromination reaction of alkenes and the correlations found between the global and local charge transferred with the transition energy of the charge transfer bands and the kinetic rate constants indicate that the nucleophilic attack of alkenes to bromine is the electronic process controlling the reactivity in the formation of the electron donor-acceptor complexes in this reaction. The 2-parabolas model is used in studying the nitrosation of aromatic compounds where colorful electron donor-acceptor complexes are formed. In this case, and like previous applications of the 2-parabolas model, the consistent usage of the model mandates the explicit consideration of reaction conditions in preparing the reactants to have a direction of electron transfer that is consistent with the chemical potential differences. For the nitrosation reaction this implies considering the nitrosonium cation as the charge acceptor. Both applications support that the charge transferred predicted from chemical reactivity models can be used as a scale to measure the nucleophilicity in reactivity trends. Graphical Abstract ᅟ.

Structural aspects of two α-dihydrazones displaying a complete survey of intermolecular interactions.

The compounds (2'E,2'E)-2,2'-(propane-1,2-diylidene)bis[1-(2-nitrophenyl)hydrazine], C15H14N6O4, (I), and (2Z,3Z)-ethyl 3-[2-(2-nitrophenyl)hydrazinylidene]-2-[2-(4-nitrophenyl)hydrazinylidene]butanoate tetrahydrofuran hemisolvate, C18H18N6O6·0.5C4H8O, (II), are puzzling outliers deviating from a general synthetic route aimed at the preparation of substituted pyrazoles. Possible reasons for this outcome, which is exceptional in an otherwise firmly established synthetic procedure, are analyzed. Compound (I) is unsolvated, while compound (II) crystallizes with a tetrahydrofuran solvent molecule lying on an inversion centre. The ethoxycarbonyl chain of (II), in turn, appears disordered into two equally populated (50%) moieties. In both structures, a plethora of different commonly occurring weak intermolecular interactions [viz. π(phenyl)...π(phenyl), π(C=N)...π(C=N), π(phenyl)...π(C=N), N-H...O and C-H...O] appear responsible for the crystal stability. Much less common are the short O(nitro)...O(nitro) contacts which are observed in the structure of (I), an example of unusual `electron donor-acceptor' (EDA) interactions.

Estudio teóricoddel efecto isotópico de hidrógeno en el aducto borano-carbonilo / Theoretical study of the hydrogen isotope effect on the borane-carbonile adduct / Estudo teorico do efeito isotopico de hidrogeno no aducto borano-carbonilo

Se estudió el efecto de la sustitución isotópica de hidrógeno sobre la geometría, la estructura electrónica y la estabilidad del aducto borano-carbonilo, mediante el método de orbitales moleculares nucleares y electrónicos (OMNE) implementado en el paquete computacional APMO. Se encontró que el aumento de la masa isotópica acorta las distancias de enlace boro-isótopo y carbono-oxígeno, mientras que alarga la distancia boro-carbono. Se determinó además la estabilidad del aducto a partir de las energías de formación y las distancias de enlace B-C. Se encontró que el aumento de la masa isotópica debilita el enlace B-C. Una primera explicación de este fenómeno en términos del concepto de acidez de Lewis predijo resultados contrarios a los encontrados, mientras que un modelo de reactividad basado en las diferencias de las energías de los orbitales LUMO del borano permitió dar cuenta de este efecto.

We have investigated the hydrogen isotope effect on the geometry, the electronic structure and the stability of the borane-carbonile adduct, by using the nuclear-electronic molecular orbital method (NEMO) which has been implemented in the APMO software. We have found that an increase of the mass of the hydrogen isotope reduces the boron-hydrogen and carbon-oxygen bond lengths while increasing the boron-carbon distance. In this study, the stability of the adduct has been analyzed in terms of formation energies and B-C bond distances. We have found that the increase of the isotope mass weakens the B-C bond. We tried to give an explaination to this phenomenon based on Lewis acidity concept but it predicted the wrong results. A reactivity model based on the energy differences of borane LUMO orbitais offered a correct explaination to this effect.

Temos estudado o efeito da substituição de isótopos de hidrogénio sobre a geometria, estrutura electrónica e da estabilidade do aduto Borana-carbonil, através do mêtodo de orbitais moleculares-core versões (OMNE) implementado no pacote computacional APMO. Descobrimos que um aumento da isótopo massa encurta as distâncias de ligação boro-carbono-isotópica de oxigênio e aumenta a distância, enquanto boro-carbono. Foi ainda determinada a estabilidade do aduto de as energias de formação e distâncias de ligação BC. Nós descobrimos que o aumento da massa isotópica minar a relação BC. Uma explicação para este fenômeno em termos de conceito de acidez de Lewis predita resultados contrários aos encontrados enquanto um modelo baseado em diferenças de reatividade nas energias dos orbitais LUMO do Borana autorizados a conta para este efeito.