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Romanelli G.P.,National University of La Plata | Virla E.G.,Planta Piloto de Procesos Industriales Microbiologicos PROIMI | Duchowicz P.R.,Institute Investigaciones Fisicoquimicas Teoricas y Aplicadas INIFTA | Gaddi A.L.,National University of La Plata | And 4 more authors.
Journal of Agricultural and Food Chemistry | Year: 2010

A simple, clean, solvent-free preparation of flavones by the use of a silica-supported Preyssler heteropolyacid as reusable catalyst is described. High selectivity and very good yields (87-94%) were obtained in short reaction times (7-13 min). Bioassays for insecticidal activity against Spodoptera frugiperda were carried out with a set of flavones. Bioassays showed that some of the flavones had moderate insecticidal activity. Quantitative structure-activity relationships were established on the available data with the purpose of predicting the insecticidal activity of a number of structurally related flavones. A relationship between the molecular structure and biological activity is proposed. © 2010 American Chemical Society. Source


Torres S.,Planta Piloto de Procesos Industriales Microbiologicos PROIMI | Pandey A.,Regional Research Laboratory | Castro G.R.,National University of La Plata | Castro G.R.,Tufts University
Biotechnology Advances | Year: 2011

Organic-solvent-tolerant bacteria are considered extremophiles with different tolerance levels that change among species and strains, but also depend on the inherent toxicity of the solvent. Extensive studies to understand the mechanisms of organic solvent tolerance have been done in Gram-negative bacteria. On the contrary, the information on the solvent tolerance mechanisms in Gram-positive bacteria remains scarce. Possible shared mechanisms among Gram-(-) and Gram-(+) microorganisms include: energy-dependent active efflux pumps that export toxic organic solvents to the external medium; cis-to-trans isomerization of unsaturated membrane fatty acids and modifications in the membrane phospholipid headgroups; formation of vesicles loaded with toxic compounds; and changes in the biosynthesis rate of phospholipids to accelerate repair processes. However, additional physiological responses of Gram-(+) bacteria to organic solvents seem to be specific. The aim of the present work is to review the state of the art of responsible mechanisms for organic solvent tolerance in Gram-positive bacteria, and their industrial and environmental biotechnology potential. © 2011 Elsevier Inc. Source


Romero C.M.,Planta Piloto de Procesos Industriales Microbiologicos PROIMI | Pera L.M.,Planta Piloto de Procesos Industriales Microbiologicos PROIMI | Olivaro C.,University of the Republic of Uruguay | Vazquez A.,University of the Republic of Uruguay | Baigori M.D.,Planta Piloto de Procesos Industriales Microbiologicos PROIMI
Fuel Processing Technology | Year: 2012

The use of biocatalysts in fuel industry is an interesting and greener alternative. In this connection, it was found that the chain-length selectivity profile of a solvent-tolerant lipase activity from Aspergillus niger MYA 135 determined in both hydrolytic and synthetic reactions depended on the way that the enzyme was prepared. Indeed, a mycelium-bound (Mb) lipase activity obtained either in presence or absence of 2% olive oil as well as a lyophilized supernatant extract obtained in presence of 2% olive oil showed different specificity constants (1/α). Thus, the highest substrate specificity in hydrolysis reaction was observed toward a long-chain fatty acid (C18; 1/α = 1.0) with the constitutive Mb-lipase in organic medium. In addition, this lipase preparation was specific toward the synthesis of methyl palmitate during esterification (1/α = 1.00) and ethyl palmitate in transesterification (1/α = 0.93). Interestingly, the induced Mb-lipase was a highly reactive biocatalyst preparation in both transesterification (58% of the reactions displayed 1/α > 0.5) and esterification (88% of the reactions displayed 1/α > 0.7) reactions. On the contrary, the induced lyophilized supernatant was the most specific enzymatic system showing a clear preference for linoleic acid in esterification reactions (1/α around of 0.77 for all acyl acceptors tested). © 2012 Elsevier B.V. All rights reserved. Source

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