Impact of environmental stress on biochemical parameters of bacteria reducing chromium

Chromium pollution is produced in connection with industrial processes like in tanneries. It has been suggested that bioremediation could be a good option for clean up. The stress effect of variable chromate levels, pHs and growth temperatures on biochemical parameters of two Cr(VI) reducing bacterial strains Pseudomonas aeruginosa Rb-1 and Ochrobactrum intermedium Rb-2 was investigated. Transmission electrone microscopy (TEM) was performed to study the intracellular distribution of Cr(VI). It was observed that initial stress of 1000 µgmL-1 caused significant enhancement of all studied biochemical parameters at pH 7.0 and growth temperature of 37 °C showing great bioremediation potential of the strains. Transmission electron microscopy revealed that the distribution of chromium precipitates was not uniform as they were distributed in the cytoplasm as well as found associated with the periplasm and outer membrane. Fourier transform infrared spectroscopy showed the possible involvement of carboxyl, amino, sulpohonate and hydroxyl groups present on the bacterial cell surface for the binding of Cr(VI) ions. Cr(VI) stress brought about changes in the distridution of these functional groups. It can be concluded that the investigated bacterial strains adjust well to Cr(VI) stress in terms of biochemical parameters and along that exhibited alteration in morphology.

Heteroantagonismo entre estirpes de Enterobacter agglomerans isoladas de urubu (Coragyps atratus) como produtoras e Pseudomonas aeruginosa como reveladoras / Evaluation of the heteroantagonism between Enterobacter agglomerans strains isolated from vulture (Coragyps atratus) for production and Pseudomonas aeruginosa as developed

Avaliou-se o heteroantagonismo entre Enterobacter agglomerans isolada do trato gastrintestinal de urubu (Coragyps atratus) e Pseudomonas aeruginosa isoladas do ambiente hospitalar. Foram utilizados o método de sobrecamada ou lento e a técnica direta ou de poços. Pelo método da sobrecamada, de 196 testes realizados para pesquisa da atividade antagonista, foi detectada a presença de halos de inibição relacionados ao fenômeno de heteroantagonismo em 118 deles (60,2 por cento). Pelo método de poços, obtiveram-se resultados semelhantes. As sete amostras de E. agglomerans foram capazes de realizar heteroantagonismo nas condições testadas, que foram detectados pela formação de halos claros de inibição. O extrato de levedura adicionado a 1 por cento no meio de cultura foi um suplemento adequado para a demonstração do antagonismo.

The heteroantagonism between Enterobacter agglomerans, isolated from the gastrointestinal tract of American vulture Coragyps atratus, and Pseudomonas aeruginosa isolated from a hospital environment was evaluated. The slow (layer) and the wells (direct) techniques were tested, using agar and soy tryptone broth pH 7.3 at 37ºC. Through the slow method from 196 tests, inhibition growth halos, related heteroantagonism phenomenon observed in 118, corresponding to 60.2 percent positive results. Equivalent positive results were detected using wells (direct) methodology. The seven samples of E. agglomerans tested were capable of revealing heteroantagonism in the experimental conditions; antagonism reveled by the presence of a clear growth inhibition halo. The added 1 percent yeast extract to media was adequate for revealing antagonisms best.

Alteraciones ultraestructurales en la pared celular de Pseudomonas Aeruginosa inducidas por Amikacina / Ultrastructure alterations in the cellular wall of Pseudomonas Aeruginosa induced by Amikacin

Los antibióticos del grupo de los aminoglicósidos se introdujeron en 1944 con la estreptomycina. Actualmente ese grupo incluye antibióticos naturales y semisintéticos como la amikacina, droga indicada para el tratamiento de infecciones por Pseudomonas aeruginosa. La acción fundamental de esta droga es sobre la síntesis proteica, no obstante para ingresar al citoplsma debe interaccionar con componetes de la membrana externa, lo que se asocia con una acción bactericida. Se sometió la cepa ATCC 27853 de Pseudomonas aeruginosa a la acción de sulfato de amikacina y como control se cultivó la bacteria en el medio libre de antibióticos. Se cosecharon las bacterias; se fijaron con una mezcla de glutaraldehido al 2,5 por ciento, rojo de rutenio al 0,075 por ciento y lisina 50 mM y se procesaron para microscopía electrónica. Se observaron alteraciones en la pared bacteriana, como separación de sus componentes y la membrana externa apareció más ondulada que en los controles no tratados con el antibiótico; además en el citoplasma de las bacterias tratadas aparecieron zonas claras aparentemente debidas, a retracción del citoplasma.