Cultivability of Salmonella typhi, Vibrio cholerae and enteropathogenic Escherichia coli in water microcosm in the presence of Eucalyptus microcorys leaves extract: Effect of the concentration of leaves extract and incubation temperature

Abstract

This study aimed to assess the effect of the concentration of an aqueous extract of a Myrtaceae (Eucalyptus microcorys) on bacterial survival under various temperature conditions. At 7°C, the highest concentration of cultivable cells were 21.30, 21.32 and 21.08 (Ln (CFU/100 ml)) respectively at the concentration of extract solution 1, 1.5 and 2% for enteropathogenic E. coli, 18.12, 16.27 and 15.31 (Ln (CFU/100 ml)) at 1, 1.5 and 2% for S. typhi, and 22.32, 22.23 and 19.99 (Ln (CFU/100 ml)) at 1, 1.5 and 2% for V. cholerae. At 23 and 37 °C, the highest concentrations of cultivable enteropathogenic E. coli, S. typhi and V. cholera were all noted at the extract concentration 1%. The hourly cell inhibition rate of enteropathogenic E. coli varied from 0.35 to 0.81, from 0.42 to 1.07, and from 0.44 to 1.05 h-1 respectively at the extract concentration 1, 1.5 and 2%. That of S. typhi varied respectively from 0.55 to 0.65, from 0.62 to 0.69, and from 0.67 to 0.76 h-1. It varied respectively from 0.29 to 0.40, from 0.32 to 0.48 and from 0.43 to 0.86 h-1 for V. cholera. Secondary metabolites found in the plant extract would have an impact on the variation of the CFUs abundance noted.