MICROBIOLOGICAL EVALIATION OF WATER QUALITY FROM SÃO JOÃO MICRO-BASIN, PORTO NACIONAL-TO, BRAZIL.

Abstract

The São João stream micro-basin, has its origin located in the Pilão Farm county, Porto Nacional -TO, and it runs through several rural properties and also in some city districts, such as: Jardim Querido, Jardim Umuarama, Setor Santa Helena and Villa Nova, flowing into the Tocantins river. The stream, receives considerable chemical, physical and biological pollution both in rural and urban zones. It´s mainly used for municipal water supply and irrigation. By systematical sampling along strategic points on the stream, were studied bacteriological indicators in order to evaluate the water quality. Water samples were analyzed microbiologically in accordance with the technique of multiple tubes and filtering membrane, and specific methods for Enterobacteriaceae culture. The minimum and maximum values founded for total coliform and faecal coliform were: 0,17 x 102 - 660,0 x 102, 2,0 x 102 – 300,0 x 102. Were isolated and identified as representatives of the families Enterobacteriaceae: Escherichia coli, Proteus mirabilis, Citrobacter diversus, Citrobacter freundii, Enterobacter aerogenes, Serratia odorifera, Salmonella sp and Edwardsiella tarda. The utilization of the water from the São João stream is completely improper for human use without previous disinfection and for irrigation of vegetable gardens and plantations and for other types of products consumed in natura.