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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