INHIBITION OF CLOSTRIDIUM-BOTULINUM GROWTH AND TOXIGENESIS IN A MODELGRAVY SYSTEM BY COINOCULATION WITH BACTERIOCIN-PRODUCING LACTIC-ACID BACTERIA

The ability of several lactic acid bacteria (LAB) to inhibit Clostridi um botulinum toxigenesis was investigated. Acidification studies ident ified the bacteriocinogenic strains Lactococcus lactis ATCC 11454 and Pediococcus pentosaceus ATCC 43200 as the most promising based on thei r ability to rapidly acidify a model gravy system. These two strains, a third bacteriocinogenic strain Lactobacillus plantarum BN, and nonba cteriocinogenic strains as controls were then coinoculated along with C botulinum type A and B spores into a model gravy system to determine if bacteriocin production and acidification are effective in preventi ng C botulinum growth and toxin production. Triplicate tubes of gravy- like media containing either 0 or 0.5% glucose were coinoculated with the LAB at 10(4) CFU/ml and with the pool of heat-shocked C botulinum spores at 10(2), 10(4), and 10(6) CFU/ml and incubated anaerobically a t 15, 25, or 35-degrees-C. The media were monitored for C. botulinum g rowth, toxin production, and acidity. At 15-degrees-C, both the bacter iocinogenic and nonbacteriocinogenic strains of L. lactis and L. plant arum prevented toxigenesis in gravy containing glucose at all C botuli num inocula levels. The bacteriocinogenic and nonbacteriocinogenic str ains of P. pentosaceus prevented toxin production by C botulinum at 10 (2) and 10(4) CFU/ml in the presence of glucose. P. pentosaceus 43200 was the only strain tested showing inhibition in the absence of glucos e, preventing toxigenesis by C botulinum at 10(2) CFU/ml. At 25 and 35 -degrees-C, none of the lactic acid bacteria tested prevented toxigene sis. The results suggest that acid production by these strains of LAB may afford some protection against mild temperature abuse and that bac teriocin production had little if any additional effect. The biopreser vation system was ineffective at temperatures of 25 and 35-degrees-C.