RESISTANCE TO CHLORINE OF FRESH-WATER BACTERIAL STRAINS

The disinfectant properties of chlorine have been known for centuries but in the last few years water chlorination has attracted some critic ism due to its secondary effects and the increased resistance of bacte rial strains to chlorine inactivation. In this paper the kinetics of i nactivation by chlorine of different Gram-positive and Gram-negative b acterial strains isolated from chlorinated water is studied. The Gram- positive strains were more resistant to chlorine and the behaviour of some of them in the presence of chloramphenicol suggests either the sy nthesis of unique proteins or aggregation of the bacteria as mechanism s of resistance to inactivation. The concept of K-i, the inactivation rate constant, by comparison with K-s in Michaelis-Menten enzyme kinet ics (considering enzymic saturation), or with K-s in Monod growth kine tics (considering limiting rates of transport and metabolism of substr ates), may be an interesting parameter to define microbial resistance to disinfectants and toxics.