Authors: Karmen GODIČ TORKAR, Martina ODER*
Corresponding author: Martina ODER
Type of paper: Original scientific article
Issue: Volume 12 | number 1 – 2018
Abstract:
The influence of temperature, disinfectant and water softener for drinking water preparation on the bacterial growth of Legionella pneumophila was examined. The optimal temperature for bacterial growth was 36 °C. At the incubation temperature of 15 °C the multiplying of bacteria slowed down, as confirmed by the bacteriostatic effect of this temperature. The number of bacteria was after the first 24 h of incubation at 55 °C reduced by more than 6 log in comparison to the culture at 36 °C. After 10 minutes of exposure to the disinfectant dichloroisocyanuric acid, the number of bacteria in the culture decreased for 1.4 log CFU mL-1, followed by an intensive growth immediately after the disinfectant degradation. The number of bacteria was up to 72 hours incubation even higher than in the control sample without a disinfectant, and then the number in both samples equalled at approximately 7.3 log CFU mL-1. Sodium polyphosphate used as a water softener stimulated the bacterial growth. The largest difference in growth was observed after 72 h of incubation, which was 1.9 log CFU mL-1 higher in samples with sodium polyphosphate in comparison to those without the softener.
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