QUANTIFICATION AND IDENTIFICATION OF Aeromonas spp. IN ESTUARINE SURFACE WATER OF THE BACANGA RIVER, SÃO LUÍS, MA (BRAZIL)

Abstract

To quantify and identify Aeromonas spp., 90 samples of estuarine surface water were collected from the Bacanga’s river in São Luís/MA, from March to October 2007. Samples were submitted to spread directly in Gel Salt Phosphate Agar method (CFU/mL) and by the Most Probable Number (MPN/100 mL) in Tripticase Soya Broth. The physical and chemical parameters: temperature (°C), salinity (%), dissolved oxygen (mg/L), pH, ammonia-N (N-NH4+) (mM/L) and nitrite (mM/ L) were analyzed to evaluate possible influence of the release of domestic sewage "in natura" in the proliferation of these bacteria in the estuarine environment. The results obtained indicated a wide dissemination of Aeromonas in the estuary, with values ranged between 4.0 x101 to 1.3x108 CFU/mL, whereas the values for MPN/100 mL ranged between 2.3x104 to 1.6x107. In relation to physical and chemical parameters, only temperature, salinity, pH and ammonia-N present significant correlation on the growth of bacteria in the environment studied. Seasonal variations were verified by the higher indices of Aeromonas obtained during the rainy season and the proximity with the sources point of domestic sewage. High frequency of Aeromonas in the Bacanga estuary represents risk to the public health, since this bacterium is commonly associated with gastroenteric disease and extra-intestinal infections.