Objective: To compare the antimicrobial activity (The minimum supporting and maximum inhibiting pH values) of 3 organic (acetic, lactic, citric) and one morgonic (hydrochloric) acids aginst S. aureus growth.
Design: Experimental study, multiple factorial analysis using inoculation technic.
Procedure: The effects of pH (6 to 4 with 0.2 unit intervals) adjusted by three organic (acetic, lactic, citric) and one inorganic (Hydrochloric) acids, 3 levels of temperature (15, 25, 35 C) stared up to 14 days were evaluated on the growth of S. aurevs with inoculum level of 105/mI in Brain heart infusion broth (BHI) the pH border of growth and no growth was determined based on the turbidity of BHI after 14 days, and the pH border of survival and death of organism was determined using a subculture from no growth condition of BHI samples on Baird Parker agar plates at the end of 14 days meubation.
Results: The highest pH values of growth and no growth were observed in the case of acetic acid (5.2 and 5, 5.4 and 5.2, 5.8 and 5.6 at 35, 25 and 15 C, respectively), where as, the lowest pH values belonged to hydrochloric acid (with <4 and 4 at 35 and 25 C, and 5 and 5.2 at 15 C). The bacteriostatic and bacteriocidic effects of acids were in the order of acetic> lactic> citric> hydrochloric. These effects decreased with increasing the temperature of storage in all of he acids used in this study. J. Foe. Vet. Med. Univ. Tehran. 57, 2: 37-41, 2002.