EFFECT OF EDTA ON THE GERMINATION OF AND OUTGROWTH FROM SPORES OF Clostridium botulinum 62‐A

Abstract

SUMMARY –EDTA, in concentrations above 2.5 mM, was found inhibitory to germination of and outgrowth from spores of C. botulinum Type A and to toxin production in a fish homogenate. Inhibitory action was influenced by pH of the medium in the range pH 6.5–8.1, the action increasing with pH. It was influenced by Mg and Ca concentrations in the medium, equimolar concentrations of added CaCl2 or MgCl2, completely erasing the growth inhibitory action. Initial spore concentration also influenced inhibitory efficacy–the higher the spore concentration, the higher the EDTA concentration required for inhibition. There was no evidence that EDTA, in any concentration used, promoted spore germination. Release of Ca, Mg and DPA from incubating spores was suppressed to varying extents by 5.0 and 10 mM EDTA.

Growth and Heat Resistance of Clostridium SporogenesPA 3679 Spores Heated and Recovered in Acidified Media

“…The presence of EDTA in the recovery medium increased the percentage of inhibition at pH 7.0 and 6.7 (Tab]e 1) in spores both with heat treatment (125°C, 30 s) and without, although the increase was significant (P :::; 0.05) only in untreated spores. As the table shows, there is a pH-EDTA interaction, as was also found by Winaro et al (21) with spores of Clostridium botulinum. However, the mechanisms of the pH-EDTA interaction still remain obscure.…”

Use of a novel method to characterize the response of spores of non-proteolytic Clostridium botulinum types B, E and F to a wide range of germinants and conditions

“…In response to different germinants, spores of proteolytic Cl. botulinum germinated optimally at pH 6á5±7á5, but not below pH 4á8 or above pH 9á2 (Rowley and Feeherry 1970;Winarno et al 1971;Ando 1973a); strain differences were also identi®ed (Blocher and Busta 1985). A predictive model of the effect of temperature (15±30°C), pH (5á5±6á5) and NaCl (0á5±4á0%) on germination of spores of strain 56A in Brain Heart Infusion Broth has been published (Chea et al 2000).…”

“…In response to different germinants, spores of proteolytic Cl. botulinum germinated optimally at pH 6·5–7·5, but not below pH 4·8 or above pH 9·2 (Rowley and Feeherry 1970; Winarno et al . 1971; Ando 1973a); strain differences were also identified (Blocher and Busta 1985).…”