Use of the aqueous extract of Eucalyptus microcorys for the treatment in microcosm, of water containing Enterococcus faecalis: hierarchisation of cells' inhibition factors

An experimental study in aquatic microcosm was carried out to determine the major factors involved in the inhibition of Enterococcus faecalis in the presence of aqueous extract of Eucalyptus microcorys. The planktonic bacterial cells remained in various concentrations of the aqueous solution at light intensities which fluctuated between 0 and 3,000 lx and incubation periods which ranged from 3 to 24 hours. A hierarchisation of studied factors revealed that the aqueous extract concentration, followed by experimental temperature, light intensity and incubation duration influence the inhibition of E. faecalis cells, respectively, with a rate of 86.82%, 7.03%, 5.25% and 0.90%. The cell abundances dropped significantly at 1.5% (λ1⁄4 0.491 and F1⁄4 5.518) and 2% (λ1⁄4 0.568 and F1⁄4 4.055) concentrations coupled with 1,000, 2,000 and 3,000 lx. The highest light intensities and extract concentration produce the highest log removal values. The disinfectant properties of E. microcorys were evaluated by the Chick–Watson model. This Chick–Watson model so obtained varied between log (N/No)1⁄4 0.09 Ct and log (N/No)1⁄4 0.17 Ct for extract concentrations of 1, 1.5 and 2%. Aqueous extract of E. microcorys could be used for water disinfection.