Characterisation of antimicrobial producing lactic acid bacteria from malted barley

Thirty-three putative inhibitor-producing lactic acid bacteria (LAB) were i solated from malted barley based on their ability to inhibit growth of two indicator strains. Eleven of the inhibitor-producing LAB produced an antimi crobial activity which was active across a wide pH range, relatively insens itive to heat treatment while sensitive to treatment with proteolytic enzym es 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-f ree supernatant with optimal production occurring in the late exponential g rowth phase. The inhibitory spectra of these isolates included various Gram -positive bacteria among which a variety of beer-spoiling bacteria.