from indigenous fermented foods and human gut ... - Thapar University

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Chapter IV: Results
Fig. 4.13 Effect of pH of medium on bacteriocin production by L. casei LAM-1. The
values shown represent mean from triplicate experiments. Bars represent the standard
error
4.12 Bacteriocin mode of action
The effect of bacteriocin on the growth of L. monocytogens ATCC 19111was examined to
establish whether it has a bactericidal or a bacteriostatic mode of action. The addition of
bacteriocin resulted in the high reduction of respective cell populations for 10 h. The addition
of 2844 AU/ml bacteriocin to a 3 h old (early exponential phase) culture of L. monocytogens
ATCC 19111 (OD600 nm = 0.1) resulted in the decrease of optical density of BHI broth from
0.1 to 0.033. After 8 h, as compared to control without bacteriocin, the viable cell count (log
CFU/ml) of L. monocytogens ATCC 19111 decreased from 7.8 to 2.8 (approximately 3 fold).
Bacteriocin led to marked decreases in both optical density and viable cell count of L.