Conservación de bacterias degradadoras de hidrocarburos / [Storage of hydrocarbon-degrading bacteria]

The storage in the laboratory of hydrocarbon degrading bacteria to be used in the decontamination of polluted sites or in the enhancement of biological treatment of industrial effluents was studied. Storage was carried out at 4 degrees C in nutrient agar and in a medium with selection pressure, liquid mineral medium with hydrocarbons. Storage at 4 degrees C with selection pressure and storage at -20 degrees C of 7 gram negative bacilli were compared. The former was the easiest method for preserving the greatest number of strains viable and active.

Aislamiento de Escherichia coli resistentes a antibióticos a partir de aguas del Río de la Plata / [Isolation of antibiotic-resistant Escherichia coli from the water of the Río de la Plata]

Water of a recreational zone of the Río de la Plata was analyzed. Levels of total heterotrophic bacteria ranged from 1.5 x 10(3) to 6.2 x 10(3) CFU/ml and total coliforms were between 5.0 x 10(2) and 7.0 x 10(3) per 100 ml. Values of fecal coliforms were between 1.0 x 10(2) and 1.3 x 10(3) per 100 ml. Among 131 E. coli strains isolated, 20.6

of cephalothin resistance was found, followed by nitrofurantoin, ampicillin, sulfisoxazole and the trimethoprim sulfamethoxazole combination. Resistance to more than one antibiotic was found in 36.7

of the strains isolated and 9.2

were resistant to three or more antibiotics. Three strains resistant to four antibiotics and one resistant to five were isolated. The highest percentage of combined resistance occurred for the pairs cephalothin-nitrofurantoin and cephalothin-ampicillin.