Comparison of enzymatic methodologies and lactose fermentation for coliform estimation in rivers

Abstract

The quantification of bacteria in the coliform group is used worldwide for the evaluation of water quality, but the methodology used for its estimation has not been considered an important factor, although studies already suggest this. In this context, the main objective of this work was to compare the methodologies of lactose fermentation in multiple tubes and the enzymatic substrate (Colilert®), used for the estimation of coliforms, from surface water samples with different degrees of pollution. Two basins were selected, the Belém river basin in Curitiba / PR, which is typically urban, and the Nhundiaquara river basin in the Serra do Mar state, in the municipality of Morretes / PR. The bacteriological analyzes were carried out simultaneously in the laboratory from the same water sample. The results indicated that the enzymatic technique is apparently more sensitive than that of lactose fermentation in the estimation of coliforms. The choice of the technique for the determination of the NMP 100 mL-1 of coliforms can vary the class of the river before the "quality condition" (Resolution of CONAMA nº 357/05) of the waters. This may make it necessary to establish a standard methodology for the assessment of compliance with the framework of water bodies, within the scope of bacteriological quality.