Bacterial density and coliform organisms in waters and oysters of Paranaguá estuarine complex, Paraná, Brazil

Abstract

The objective of the present research was to evaluate quantitatively the total coliforms and E. coli in oysters and adjacent waters of the Paranaguá Estuarine Complex and its interrelation with biotic and abiotic factors, as well as evaluate the contamination from coliforms of oysters sold in the Paranaguá market. Water and oysters were collected from April of 1997 to February of 1998, in the Paranaguá Estuarine Complex and oysters were bought from the same three merchants in the market throughout the research. Temperature, salinity and seston of the water and total heterotrophic bacteria, bacterial biomass, total coliforms and Escherichia coli in the water and in the oysters were analyzed. Temperature was higher in summer, and salinity and seston in the winter. Total heterotrophic bacteria and bacterial biomass in the water were heigher in Ostras River in July and January and total coliforms, in July. The highest values of total coliforms in oysters were observed in Rasa Island, in January. In the water, the number of E. coli was larger than 2,419 MPN.100 mL^-1 in Cobras’ Island in April and in Puruquara in July. In relation to the oysters from the market of Paranaguá, the largest values of total coliforms were registered in April and December, and E. coli in December, both from merchant 2. The results show that oysters collected in the environment as well as those from the Municipal Market of Paranaguá cannot be consumed raw without previous purification and that there is a need of an urgent reform of the legislation, including the analysis of E. coli in the oysters to be marketed.