Influencia de la concentración salina y la temperatura en la composición de ácidos grasos de membrana de Pseudomonas fluorescens GNP-OHP-3 / Influence of salinity and temperature on fatty acid composition of Pseudomonas fluorescens GNP-OHP-3 membrane

Las bacterias responden a los cambios ambientales modificando su composición, para evitar el daño que dichos cambios podrían ejercer. Una de las modificaciones más importantes es la variación de la composición de los ácidos grasos de las membranas celulares, que le permite mantener la homeoviscosidad ante situaciones de estrés. Trabajos previos han estudiado la acción de la temperatura, presión hidrostática y diferentes solventes sobre cepas de Pseudomonas putida. En este trabajo se estudió la acción conjunta de la temperatura y la salinidad sobre la composición de ácidos grasos de membranas celulares de Pseudomonas fluorescens GNP-OHP-3, una cepa bacteriana aislada de un hábitat contaminado con petróleo. Pseudomonas fluorescens GNP-OHP-3 respondió a las variaciones de temperatura modificando los ácidos grasos de sus membranas de manera similar a lo descripto en otros integrantes de su género: ante el aumento de temperatura se observó un incremento de ácidos grasos saturados y una disminución de los ácidos grasos insaturados. En el rango de concentraciones salinas ensayadas las variaciones de los ácidos grasos mayoritarios fueron en general erráticas. La respuesta de los ácidos grasos ciclo propano pudo expresarse con ecuaciones matemáticas que permitieron predecir el porcentaje de estos ácidos en relación a la concentración de cloruro de sodio.

The bacteria respond to environmental changes modifying their composition. One of the most important modifications is the variation on fatty acid composition of cellular membranes to maintain the homeoviscosity. The action of temperature, hydrostatic pressure and solvents on Pseudomonas putida has been thoroughly studied. In this paper, the combined action of the temperature and salinity on fatty acid composition of cellular membranes of Pseudomonas fluorescens GNP-OHP-3, a bacterial strain isolated from a petroleum contaminated habitat, was studied. The modifications in the fatty acid composition of Pseudomonas fluorescens GNP-OHP-3 membrane were similar to those described for other members of Pseudomonas: an increase in saturated fatty acids and a decrease in unsaturated fatty acids were observed with the increase of the temperature. Variations of main fatty acids were in general erratic in the range of assayed saline concentrations. The variation of cycle propane fatty acids could be expressed with mathematic equations that allowed to predict their percentage in relation to sodium chloride concentration.

Biodegradabilidad de componentes de mezclas naturales de hidrocarburos previamente sometidas a landfarming / Components biodegradability of natural hydrocarbon mixtures previously subjected to landfarming

La compleja composición del petróleo crudo, derivados y deshechos de las diferentes etapas de la industria petrolera hacen de este producto una mezcla que presenta diferentes dificultades para su eliminación por métodos biológicos. El objetivo de este trabajo fue mostrar el potencial de biodegradación de comunidades bacterianas autóctonas frente a hidrocarburos obtenidos de cuatro sitios contaminados y sometidos a biorremediación, en un sistema de Landfarming por casi un década. Los resultados mostraron una marcada diferencia de biodegradabilidad de las tres principales fracciones alifáticas, aromáticas, y polares, obtenidas por cromatografía en columna. Si bien todas las fracciones fueron utilizadas como fuente de carbono y energía, existieron variaciones importantes en la producción de biomasa entre ellas, como asimismo en la cinética de biodegradación, según la composición de cada fracción.

Análisis de genes catabólicos de hidrocarburos aromáticos en cepas aisladas de suelos de la Patagonia / Analysis of aromatic hydrocarbon catabolic genes in strains isolated from soil in Patagonia

Seven strains belonging to genus Pseudomonas were isolated from an enrichment with hydrocarbon mixtures. Tests for enzyme activities showed that five strains used predominantly the catabolic meta-pathway for aromatic hydrocarbon degradation. Furthermore, the xylE gene which encodes a catechol 2,3-dioxygenase was amplified by PCR, and in two strains the nahAc gene, a key enzyme for naphthalene catabolism, was also found. The xylE gene might be a good marker to identify aromatic hydrocarbon degrading bacteria in soils from Patagonia.

Aspectos taxonómicos de cepas patagónicas y cepas tipo del genero Desulfovibrio / [Taxonomic aspects of strains from Patagonia and type strains of Desulfovibrio]

Fourteen type strains and 42 indigenous strains of Desulfovibrio were studied and taxonomic numeric methods were applied (Cluster Analysis, Principal Coordinates Analysis, Correspondence Analysis). The type strains as well as the indigenous ones share a low quantity of carbon and energy sources. Type strains have a taxonomic structure which shows net clusters; indigenous strains possess a grading (or [quot ]adjustment[quot ]) in their positive reactions hence the taxonomic structure is not so clear. Both classifications are firm since they suffer minimal changes when they are joined.

Análisis de coordenadas principales y análisis factorial de correspondencia aplicados a la taxonomía de cepas tipo del género Desulfovibrio / [Analysis of principal coordinates and factorial correspondence analysis applied to the taxonomy of type strains of Desulfovibrio]

Bacterial taxonomy using mathematical methods can be carried out with different techniques. Two techniques are used in this paper: analysis of principal coordinates and factor analysis of correspondences. The first one allows 2 and 3 dimension graphs of bacteria, thus showing their relationship considering proximity. The second one gives new data because it is an analysis which allows to connect bacteria to the reactions which identify them. In order to carry out these analyses 14 strains of the Desulfovibrio genus were studied, thus obtaining a classification consistent with other numeric method (group analysis with Simple Matching coefficient of average bond) to which it adds new information.

Taxonomía numérica del genero Desulfovibrio por análisis de agrupamiento / [Numerical taxonomy of the genus Desulfovibrio by group analysis]

The Desulfovibrio genus has a particular interest because it includes the microorganisms connected with the corrosion produced microbiologically. The taxonomy of the genus shows disadvantages due to its metabolical and physiological characteristics. In this paper, 14 strains of the Desulfovibrio type were studied from the metabolical point of view. Numeric taxonomy was carried out according to the Group Analysis method, using and comparing the change possibilities of the method. The Consensus Method was also applied. The results obtained indicate a low metabolic activity of the strains with regard to the number of compounds which can be used as energy source. The taxonomic method showed a better structure with more clear divisions, corresponding to Simple Matching coefficient (which coincides with other symmetric coefficients and with the distance coefficient) with average bond (UPGMA). It is estimated that the present classification will vary in time with new strains with different metabolic characteristics. The two groups of bacteria correspond to those with more and less degrading ability.

Análisis de coordenadas principales y análisis factorial de correspondencia aplicados a la taxonomía de cepas tipo del género Desulfovibrio / [Analysis of principal coordinates and factorial correspondence analysis applied to the taxonomy of type strains of Desulfovibrio]

Bacterial taxonomy using mathematical methods can be carried out with different techniques. Two techniques are used in this paper: analysis of principal coordinates and factor analysis of correspondences. The first one allows 2 and 3 dimension graphs of bacteria, thus showing their relationship considering proximity. The second one gives new data because it is an analysis which allows to connect bacteria to the reactions which identify them. In order to carry out these analyses 14 strains of the Desulfovibrio genus were studied, thus obtaining a classification consistent with other numeric method (group analysis with Simple Matching coefficient of average bond) to which it adds new information.

Taxonomía numérica del genero Desulfovibrio por análisis de agrupamiento / [Numerical taxonomy of the genus Desulfovibrio by group analysis]

The Desulfovibrio genus has a particular interest because it includes the microorganisms connected with the corrosion produced microbiologically. The taxonomy of the genus shows disadvantages due to its metabolical and physiological characteristics. In this paper, 14 strains of the Desulfovibrio type were studied from the metabolical point of view. Numeric taxonomy was carried out according to the Group Analysis method, using and comparing the change possibilities of the method. The Consensus Method was also applied. The results obtained indicate a low metabolic activity of the strains with regard to the number of compounds which can be used as energy source. The taxonomic method showed a better structure with more clear divisions, corresponding to Simple Matching coefficient (which coincides with other symmetric coefficients and with the distance coefficient) with average bond (UPGMA). It is estimated that the present classification will vary in time with new strains with different metabolic characteristics. The two groups of bacteria correspond to those with more and less degrading ability.

Conducta conservadora en cáncer de mama operable: primeros resultados a 5 años / Conservative surgery in breast neoplasms: first results from 5 years

Se plantea los fundamentos para preservar la mama, con buenos resultados cosméticos y la mayor seguridad, en pacientes con Cáncer de Mama operable. Desde 1979 ingresan a nuestro protocolo 170 pacientes T1 T2 N0 N1 a M0. Todas fueron sometidas a cirugía limitada que incluye resección segmentaría de mama, extirpando el tumor rodeado por un mínimo de 2 cm. de tejido glandular sano y disección linfática axilar de los niveles glanglionares 1 y 2 por incisión separada. A los veinte días de la cirugía se inicia la telecobaltoterapia de 6.000 rads sobre la mama; se adiciona un boost de 1.000 rads sobre el lecho tumoral con Cs. 137 o radioterapia convencional. Se irradian las áreas glanglionares axila, supra e infraclavicular y las tres primeras estaciones de la cadena mamaria interna homolateral con 5.000 rads. Si la axila es anatomopatológicamente positiva, se agrega un boost axilar posterior de 1.000 rads más hormono-quimioterapia adyuvante con FAC-Tamoxifeno por 6 ciclos. Opcionalmente se efectuó el esquema de tratamiento del Instituto de Tumores de Milán, en algunas pacientes con tumores pequeños. Quince pacientes han superado los 5 años de seguimiento y todas viven: 13 libres de enfermedad, 1 con recidiva local y 1 con metástasis a distancia. De las restantes 155 pacientes el seguimiento promedio es de 28 meses: 151 viven libres de enfermedad aparente, 2 con recidivas locales y 2 con metástasis a distancia. Los resultados cosméticos son bastante buenos: con 40% de radiosecuelas leves, un 14% de moderadas y 1 sola paciente con radiosecuelas severa. Se discute algunos interrogantes sobre cuales serían las técnicas menos mutilantes, pero que conserven iguales índices de seguridad. Se concluye en considerar la efectividad del manejo conservador de los casos operables en cáncer de mama