ESCHERICHIA-COLI O157-H7 GROWTH IN LABORATORY MEDIA AS AFFECTED BY PHENOLIC ANTIOXIDANTS

Five strains of Escherichia coli 0157:H7 with ATCC 11775 E. coli were grown in brain heart infusion (BHI) broth (pH 5.8, adjusted with citri c acid) and treated with butylated hydroxyanisole (BHA), butylated hyd roxytoluene (BHT), tertiary butylhydroquinone (TBHQ), and propyl galla te (PG) individually or combined. Additives ranged from 100-400 ppm wi th inocula levels between 5 and 10(4) CFU/mL in tissue culture plates or in flasks; samples were incubated at 4 degrees C or 37 degrees C fo r 24 hr. Additive antimicrobial efficacy varied with inoculum level an d incubation temperature. BHA at greater than or equal to 200 ppm was bactericidal on all strains. Poly-hydroxyl additives (TBHQ, PG) were l ess effective at 4 degrees C. BHA-BHT combinations were synergistic at 4 degrees C.