BMC Microbiology

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		++	++	+++	++	+	++

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

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