RESUMO Membranas de microfiltração em cerâmica tubular foram preparadas por extrusão de misturas de argilas naturais (NC) e argilas tratadas termicamente (TC) em diferentes frações com a adição de amido de mandioca catiônico. Estudos anteriores verificaram que membranas contendo TC possuíam maior permeabilidade hidráulica e fluxo permeado do que aquelas que continham somente NC para a aplicação em filtração tangencial. Entretanto, as membranas TC tinham uma baixa resistencia mecânica. Assim sendo, este estudo teve como objetivo aumentar a resistência mecânica sem afetar adversamente seu fluxo permeado e permeabilidade hidráulica. As características físicas, mineralógicas e morfológicas das membranas foram determinadas. As membranas foram usadas para microfiltração de microalga Acutodesmus obliquus com pressão aplicada de 1 bar com taxa de fluxo volumétrica de 250 L/h em uma temperatura de 10 ± 5°C. A eficiência de cada membrana cerâmica foi avaliada em termos de fluxo permeado para água e microalga e permeabilidade hidráulica. A mistura de 70% de TC, 15% de fração de amido e sinterizado em 1150ºC exibiu ótimo desempenho em resistência mecânica (15.1±0.2 MPa), fluxo permeado de água de 522.4±0.3 Kg•m-2•h-1, fluxo permeado de microalga de 114.8±0.8 Kg•m-2•h-1 e permeabilidade hidráulica de 568.0±0.3 Kg•m-2•h-1•bar.

ABSTRACT Tubular ceramic microfiltration membranes were prepared by extruding thermally treated clay (TC) and raw clay (NC) mixtures in different fractions with the addition of cationic manioc starch. Previous studies have verified that membranes containing TC possess higher hydraulic permeability and permeate flow values than those containing only NC for application in crossflow filtration. However, TC membranes had a low mechanical strength. Therefore, this study aimed to increase the mechanical strength without adversely affecting their permeate flow and hydraulic permeability. The physical, mineralogical, and morphological characteristics of the membranes were determined. The membranes were used for microfiltration of Acutodesmus obliquus microalgae with applied pressure of 1 bar with a volumetric flow rate of 250 L/h at a temperature of 10 ± 5°C. The efficiency of each ceramic membrane was evaluated in terms of the permeate flow for water and microalgae and hydraulic permeability. The mixture of 70% TC, 15% starch fractions and sintered at 1150°C exhibited optimal performance in mechanical strength (15.1±0.2 MPa), water permeate flow of 522.4±0.3 Kg•m-2•h-1, microalgae permeate flow of 114.8±0.8 Kg•m-2•h-1 and hydraulic permeability of 568.0±0.3 Kg•m-2•h-1•bar.

Extracellular lipases from the endophytic yeast Candida guilliermondii isolated from castor leaves (Ricinus communis L.) were produced using low-cost raw materials such as agro-industrial residues and applying them in the esterification of oleic acid for evaluating their potential use in biodiesel production. After partial purification using ammonium sulfate, the enzyme was characterized and presented higher activity (26.8 ± 1.5 U mL-1) in the presence of 5 mmol L-1 NaCl at 30 ºC and pH 6.5. The production through submerged fermentation was formerly performed in 150 mL erlenmeyer flasks and, once the enzyme production was verified, assays in a 14 L bioreactor were conducted, obtaining 18 ± 1.4 U mL-1. The produced enzyme was applied in the oleic acid esterification under different solvents: hexane, cyclohexane or cyclohexanone) and different acid:alcohol molar ratios. Higher ester conversion rate (81%) was obtained using hexane and the molar ratio of 1:9 was the best conditions using methanol. The results suggest the potential for development of endophytic yeast in the production of biocatalyst through submerged fermentation using agroindustrial residues as culture medium.

Um procedimento de isolamento de mitocôndrias funcionalmente intactas de calos embriogênicos de Araucaria angustifolia foi desenvolvido pela primeira vez em nosso laboratório. Mitocôndrias isoladas por este método são metabolicamente ativas, capazes de sustentar fosforilação oxidativa como mostrado pelo controle respiratório de aproximadamente 2,4, respirando na presença de succinato como substrato. Através de experimentos de consumo de oxigênio com mitocôndrias rompidas em nitrogênio líquido foi demonstrada a presença de NAD(P)H desidrogenases alternativas, insensíveis à rotenona e estimuladas por Ca2+. O isolamento de mitocôndrias de A. angustifolia é um novo e importante instrumento para estudar plantas, permitindo a execução de múltiplas investigações a respeito da bioenergética mitocondrial e fisiologia vegetal.

A method for the isolation of coupled mitochondria from the callus of Araucaria angustifolia is described for the first time. Mitochondria were isolated from embryogenic callus of A. angustifolia. They were metabolically active, able to sustain oxidative phosphorylation as shown by respiratory control ratio values, which were about 2.4 when respiring on succinate as substrate. Oxygen uptake experiments, using freeze-thawed disrupted mitochondria, showed the presence of alternative rotenone-insensitive NAD(P)H dehydrogenases, which were stimulated by Ca2+. The procedure now described for the isolation of A. angustifolia mitochondria is an important new tool, allowing the investigation of mitochondrial bioenergetics and metabolism and physiology of plants.