RELATIONSHIP BETWEEN PSEUDOMONAS-AERUGINOSA AND BACTERIAL INDICATORS IN POLLUTED NATURAL-WATERS

The relationship between Pseudomonas aeruginosa and the faecal pollution index (total coliforms, faecal coliforms and faecal streptococci) in natural waters was established. Water samples were collected from several aquatic environments in Malaga (Spain). P. aeruginosa counts and isolation frequencies were clearly associated with the degree of faecal pollution of the studied water. The results confirmed that domestic sewage was the major source of P. aeruginosa in river and seawater, being isolated from sewage at concentrations about 10(5) cfu/100 ml. There was a close correlation between the P. aeruginosa concentration and the densities of the three faecal indicators in both river and marine waters. A significant correlation was not observed in waters with little faecal pollution because P. aeruginosa was only occasionally isolated from these waters and at very low densities. P. aeruginosa concentrations in sewage and polluted natural waters were generally 3-4 log lower than the TC densities and 2 log lower than FC and FS concentrations. TC, FC and FS could be considered adequate indicators of the presence and densities of P. aeruginosa in natural waters, especially TC in freshwaters and FS in seawater respectively, as these parameters showed the best correlations and the most parallel inactivation processes with P. aeruginosa in each environment.