Effect of Escherichia coli and Aeromonas hydrophila on Some Abiotic Properties of Water Stored in Aerobic and Anaerobic Conditions

Abstract

Few studies have been carried out to date on the influence of bacteria on variations in the abiotic properties of water. The aim of the present work was to evaluate the influence of Escherichia coli and Aeromonas hydrophila on some abiotic properties of groundwater stored under aerobic or anaerobic conditions. Experiments were performed in the presence of monospecific cells and bispecific cells. The incubation temperatures were 4˚C and 23˚C. The incubation (storage) times were 6 h, 12 h, 24 h, 48 h and 72 h. Bacteriological analyses were carried out using culture and physicochemical analyses using appropriate techniques. The results show that in the presence of monospecific cells and under aerobic conditions, E . coli abundances were relatively lower than under anaerobic conditions. The opposite was observed in the presence of bispecific cells. In most cases, minimum cell abundances were observed after 6 hours of storage. The same was true for A. hydrophila cells . The values of pH, electrical conductivity and ammonium ions in the water on the day of sampling varied over time. The pH values were relatively higher at 4˚C in the presence of E. coli cells alone, and at 23˚C in the presence of A. hydrophila cells. Ammonium ion levels were relatively higher at 4˚C under anaerobic conditions for both bacterial species. The highest electrical conductivity value was observed at 23˚C in the presence of E. coli cells, and at 4˚C in the presence of A. hydrophila cells, under anaerobic conditions. Electrical conductivity is higher in the presence of A. hydrophila with fluctuations from 169 to 285 µS/cm after 24 h incubation and 259 µS/cm after 6 hours incubation at 4˚C and 23˚C respectively. Under anaerobic conditions and in the presence of E. coli , the conductivity varied from 169 µS/cm at sampling to 274 µS/cm after 72 hours of incubation at 4˚C and from 169 to 289 after 24 hours. Under the same experimental conditions and in the presence of A. hydrophila , the electrical conductivity is higher at 4˚C with a value of 299 µS/cm after 24 hours. In the monospecific condition and under aerobic and anaerobic conditions and at an incubation temperature of 4˚C, the increase in the abundance of E. coli cells is significantly and positively correlated with the increase in pH values. In the mixed condition, pH is very significantly and positively correlated with the abundance of commensal Escherichia coli in anaerobic conditions (P < 0.01). Ammonium ions ( NH 4 + ) is significantly and negatively correlated with cellular concentrations of A. hydrophila in both aerobic and anaerobic conditions.