Antibacterial Activity of Propolis Ethanol Extract Against Streptococcus mutans as Influenced by Concentration, Temperature, pH and Cell Age

HSIN-YI YANG^1,3, WEI-LI HO², CHENG-MING CHANG³ AND CHENG-CHUN CHOU¹*

^1. Graduate Institute of Food Science & Technology, National Taiwan University, Taipei City 106, Taiwan, R.O.C.
^2. Department of Food Science and Technology, Ching Kuo Institute of Management and Health, Keelung, Taiwan, R.O.C.
^3. Department of Food Science, National Taiwan Ocean University, Keelung, Taiwan, R.O.C.

(Received: July 12, 2006; Accepted: November 10, 2006)

  
   It was found EEP exerted bacteriostatic and bactericidal effects against Str. mutans, respectively, at concentrations of 1.875 and 3.75 µg/mL or more.  At 37°C, Str. mutans was more sensitive to EEP than at 25°C while most resistant at 4°C.  Cells of test organism were most susceptible to EEP at acid pH followed by neutral and alkaline pH.  It was also noted that cells of Str. mutans in the stationary phase were more resistant, while cells in the mid-exponential phase were more susceptible to EEP.  After exposure to EEP, a marked increase in the 260 nm absorbance for the supernatant of culture, was observed, indicating the release of UV-absorbing materials.  Scanning electron micrographs also showed an increase in material with irregular shape on the surface of EEP-treated Str. mutans cells.

Key words: antibacterial activity, cell leakage, ethanol extract of propolis, Streptococcus mutans