EFFECT OF SODIUM LACTATE ON TOXIN PRODUCTION, SPORE GERMINATION AND HEAT-RESISTANCE OF PROTEOLYTIC CLOSTRIDIUM-BOTULINUM STRAINS

The effect of sodium lactate and sodium lactate combined with sodium chloride (NaCl) on toxin production by proteolytic strains of Clostridium botulinum was determined in peptone-yeast extract medium, pH 6.1. Both inhibitors were also tested for their effect on thermal destruction of spores. Additionally, the effect of sodium lactate on germination of spores was assessed. The inhibitory effect of sodium lactate was dependent on the applied incubation temperature. The best inhibition was obtained at low temperatues. Toxin production was delayed at 15 and 20-degrees-C by sodium lactate concentrations of 2 and 2.5%, respectively. Complete inhibition of toxin production at 15, 20 and 30-degrees-C occurred at concentrations of 3, 4 and >4%, respectively. Further, sodium lactate inhibited germination of the C. botulinum spores, which may partially explain the inhibitory effect of sodium lactate on growth and toxin formation. The inhibitory effect of NaCl at concentrations resulting in an identical water activity value as obtained by sodium lactate was negligible, indicating that the inhibitory effect of sodium lactate was not caused by decreasing water activity. No clear synergistic effect of sodium lactate (1.5 or 2.5%) and NaCl (2.1%) was observed.