In vitro assessment of the antibacterial effect of watery date extracts (Mozafati, Zahedi and Piaroum) on Staphylococcus aureus and Escherichia coli

Abstract The present research aimed at investigating the antibacterial effects of date extracts (Mozafati, Zahedi and Piaroum) on the stationary and exponential growth phases of Staphylococcus aureus and Escherichia coli O157: H7 in vitro. The methods used in this study included flow cytometry and culture. Carboxyl fluorescein diacetate was utilized to determine the effects of extracts and estimate bacterial survivability. Under the impacts of Mozafati, Zahedi and Piaroum extracts, the bacterial elimination percentages recorded in the log phase of S. aureus were 30.90, 86.35 and 97.18% respectively. However, the effect of exposure of E. coli to date extracts in log phase resulted in the destruction of 8.76, 24.69 and 38.97% of these bacteria respectively. The effect of the extracts on the log phase of S. aureus showed a significant increase compared to that of E.coli (p<0.05). The extracts had the maximum impacts on the stationary phase of both S. aureus and E. coli within 3h exposure time. Mozafati and Piaroum extracts yielded the highest bacterial elimination effect within 3h while Zahedi extract had the maximum effect at zero time on stationary phase of E.coli. The effect of these extracts on the stationary and logarithmic phases of growth of S. aureus and E. coli is bacteriostatic. The result of flow cytometry showed an increase as compared with that of culture. The antibacterial effect of Zahedi extract on S. aureus and E. coli proved to be meaningfully higher than those of other extracts. In order to destroy the examined bacteria in both stationary and logarithmic phase, the use of Zahedi, Piaroum and Mozafati extracts is recommended respectively.