ANTIBIOSIS OF LEUCONOSTOC-GELIDUM ISOLATED FROM MEAT

A heterofermentative lactic acid bacterium isolated from meat packaged under elevated CO2 levels was identified as Leuconostoc gelidum, based on the description of this new species by Shaw & Harding (1989). It grows well at refrigeration temperatures but not at 35-degrees-C. The organism produces an inhibitory substance that is inactivated by protease and trypsin, but not by catalase or by heating at 62-degrees-C for 30 min. The bacteriocin-like inhibitory substance is produced early in the growth cycle, at 1, 5 and 25-degrees-C. The inhibitory substance is active against a large number of closely related lactic acid bacteria, as well as a strain of Enterococcus faecalis and Listeria monocytogenes. There is initial evidence that the genetic information determining production of, and resistance to, the bacteriocin-like substance is plasmid mediated. Of the three plasmids found in this organism, loss of the 7.6 MDa plasmid resulted in loss of inhibitor production and resistance to the inhibitory substance. Loss of the 5.0 MDa plasmid did not result in a detectable phenotypic change in the organism.