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Table 2 Minimum inhibitory concentration of the natural and organic antimicrobials against L. monocytogenes, E. coli O157:H7, and S. enteritidis at pH 7.1

From: Efficacy assessment of various natural and organic antimicrobials against Escherichia coli O157:H7, Salmonella enteritidis and Listeria monocytogenes

Tested compound

Tested range

Minimum inhibitory concentration in ppm

L. monocytogenes

E. coli O157:H7

S. enteritidis

pH 7.1

pH 7.1

pH 7.1

Thymol

0–300

200 ppm

25 ppm

25 ppm

Salicylic acid

0–500

500 ppm

500 ppm

500 ppm

Acetylsalicylic acid

0–500

500 ppm

500 ppm

500 ppm

Benzoic acid

0–300

200 ppm

300 ppm

200 ppm

Sodium benzoate

0–300

300 ppm

300 ppm

300 ppm

3-t-butyl-4-Hydroxyanisole

0–300

300 ppm

300 ppm

300 ppm

Ibuprofin

0–300

50 ppm

50 ppm

NA

4-Acetamidophenol

0–300

NA

NA

NA

  1. Different concentrations of each antimicrobial were each added to 10-ml tryptone soya broth tubes and then inoculated (50 μl) of an overnight culture of the bacterial suspension. Tubes were incubated at 37 °C for 24 h. Negative and positive controls were performed. The optical density of each tube was measured using a spectrophotometer. Minimum inhibitory concentration is the lowest concentration of the assayed antimicrobial agent that inhibits the visible growth
  2. NA not applicable