Characterisation of Antimicrobial Producing Lactic Acid Bacteria from Malted Barley

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Abstract
Thirty-three putative inhibitor-producing lactic acid bacteria (LAB) were isolated from malted barley based on their ability to inhibit growth of two indicator strains. Eleven of the inhibitor-producing LAB produced an antimicrobial activity which was active across a wide pH range, relatively insensitive to heat treatment while sensitive to treatment with proteolytic enzymes indicating that the inhibitory compounds are proteinaceous in nature and therefore bacteriocin-like inhibitory substances. Ten of these eleven malt isolates were observed to secrete the inhibitory compounds into the cell-free supernatant with optimal production occurring in the late exponential growth phase. The inhibitory spectra of these isolates included various Gram-positive bacteria among which a variety of beer-spoiling bacteria.