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Table 8 The Effects of pH and heat treatment on antimicrobial activity of potential lactic acid bacteria (LAB) probiotic strains

From: Isolation, characterization, and assessment of lactic acid bacteria toward their selection as poultry probiotics

Treatment Indicator Strain Inhibition zone by
  I2 I5 I8 I13 c3 c14
Untreated E. coli +++ +++ ++ ++ +++ ++
E. coli O157: H7 ++ ++ ++ ++ ++ ++
E. faecalis ++ ++ ++ ++ ++ ++
S. Typhimurium ++ ++ ++ ++ + +
S. Enteritidis + ++ ++ ++ ++ +
L. monocytogenes ++ ++ +++ ++ + ++
Neutralized E. coli ̶̶ ̶̶ + ++ ̶̶ ̶̶
E. coli O157: H7 ̶̶ ̶̶ ̶̶ + ̶̶ ̶̶
E. faecalis ̶̶ ̶̶ + ++ ̶̶ ̶̶
S. Typhimurium ̶̶ ̶̶ ̶̶ + ̶̶ ̶̶
S. Enteritidis ̶̶ ̶̶ ̶̶ + ̶̶ ̶̶
L. monocytogenes ̶̶ ̶̶ ̶̶ ̶̶ ̶̶ ̶̶
Heat treated E. coli   ++ +++ ++ ++ +++ +++
E. coli O157: H7 ++ ++ ++ ++ ++ +++
E. faecalis ++ ++ ++ ++ ++ +++
S. Typhimurium ++ ++ ++ ++ + +++
S. Enteritidis + ++ ++ ++ ++ +++
L. monocytogenes ++ ++ +++ ++ ++ +++
Catalase treated E. coli   +++ +++ ++ ++ +++ ++
E. coli O157: H7 ++ ++ ++ ++ ++ ++
E. faecalis ++ ++ ++ ++ ++ ++
S. Typhimurium ++ ++ ++ ++ + +
S. Enteritidis + ++ ++ ++ ++ +
L. monocytogenes ++ ++ +++ ++ + ++
  1. Symbols show zones of inhibition (mm): ̶̶, no inhibition; +, weak (< 14); ++, good (15–19); +++, strong (> 20), Neutralized; supernatant treated with 6 N NaOH to obtained a pH 7, heat treated; Supernatants boiled for 10 min, Catalase treated; supernatant treated with 0.5 mg/ml catalase