The Resistance of Spores of Clostridium botulinum Type E to Heat and Radiation

Abstract

Spores of Clostridium botuliwum type E have been screened for resistance to heating in aqueous suspension a t 60, 70 and SO". D178 ranged from <0.33 min to 1.25 min. z values of eight strains were between 9.0 and 10.7, and for one strain was 7.4.Radiation survivor curves have been plotted for nine strains, and a further nine strains screened. The "shoulder" extends to about 0.4 megarad, whereafter the curve becomes exponential within a D value from 0.065 to 0.16 megarad.* Irradiations were made on spores in RCM at 0-3". and 108 (a Russian strain obtained from Prof. K. F. Meyer) were subjected to 70, 75, and 80" by Ohye & Scott (1957) and their decimal reduction ( D ) times corresponded well with those of Dolman ( 1 9 5 7~) . Schmidt (1964) heated strain Minneapolis a t temperatures between 74.5" and 85.5") obtaining D times midway between those for the strains examined by Ohye & Scott (1957). The heat resistance of strain Tenno

Factors Affecting Growth and Toxin Production by Clostridium Botulinum Type E on Irradiated (0.3 Mrad) Chicken Skins

“…However, our results showe$ that if broiler skins were kept under refrigeration (10 C or lower) or if the initial level of type E spores was low (<102/7 cm2) no toxin was produced within 18 days under aerobic conditions. The irradiation survival curve of C. botulinum type E spores in aqueous suspension was characterized by a shoulder (0.22-0.29 Mrad) followed by a logarithmic decline (D = 0.099-0.109 Mrad), similar to data found in the literature (Schmidt et al, 1962;Roberts et al, 1965;Segner and Schmidt, 1966). When the spores were suspended on chicken skins, there was a tail in the irradiation survival curve.…”

A REVIEW Tailing of Survival Curves of Bacterial Spores

“…Thus, an heterogeneity of the treatment, by way of local variations of temperature or of disinfectant concentration, can cause such tails. This has been demonstrated by Roberts & Ingram (1965). Spores heated in an open tube submersed partly in a water bath had a survival curve concave upward, whereas spores of the same batch heated in sealed ampoules had logarithmic survival curves.…”

Radiation Resistance of Spores of Clostridium Species In Aqueous Suspension

“…3, but the data are included in Table 1. It is evident that CL botulinzm type E are most sensitive, strain 16/63 being the most resistant of nine strains previously examined (Roberts and Ingram, 1965). Most of the other clostridia studied are within the over-all range in Fig.…”