EFFECT OF DIVALENT CATIONS IN THE SPORULATION MEDIUM ON THE THERMAL DEATH RATE OF BACILLUS COAGULANS VAR. THERMOACIDURANS

Abstract

In a previous paper, El-Bisi and Ordal (1956a) reported that increased levels of phosphate, in the growth and sporulation medium, significantly reduced the thermal resistance of spores of Bacillus coagulans var. thermoacidurans. It was postulated that the phosphate anion lessened the availability of divalent cations to the sporulating cells and that spores so produced possessed a reduced thermal resistance. A relationship between the calcium content and the degree of thermal resistance of bacterial spores has been suggested by Curran (1952) and by Sugiyama (1951). Williams (1929) reported that the addition of magnesium to peptone containing media yielded spores of Bacillus subtilis of increased thermal resistance. In this investigation, the effect of the divalent cations, calcium, magnesium, and manganese, added to the sporulation medium, was studied in more detail for their effect on the thermal resistance of spores of B. coagulans var. thermoacidurans. MATERIALS AND METHODS Test culture. B. coagulans var. thermoacidurans, American Type Culture Collection no. 8038, was used in this investigation. Stock cultures were maintained on thermoacidurans agar (Difco) containing additional 1 ppm MnSO4. Media. Spore crops were produced either on agar surface cultures or in broth shake cultures. Basal media used were thermoacidurans agar (proteose-peptone, 0.5 per cent; yeast-extract, 0.5 per cent; glucose, 0.5 per cent; K2HPO4, 0.5 per cent; and agar, 2 per cent) and thermoacidurans broth (the same components omitting the agar).

The Occurrence of Bacillus coagulans with High Heat Resistance

“…Youland & Stumbo (1953) found a decimal reduction time at 110" of about 0.3 min (D,,= 0-3). Thermal resistances of the same order were observed by El-Bisi & Ordal (1956a), Amaha, Ordal & Touba (1956), Amaha & Ordal (1957) and others. These and other authors also studied the effect of environmental conditions on the growth, sporulation and heat resistance of B .…”

Chemical Events During Death of Bacterial Endospores by Moist Heata

“…It was postulated that higher levels of phosphate interfered with ihe availability of the divalent cations to the sporulating cells. On the other hand, the enrichment of calcium and manganese in the sporulating medium pr'oduced spores of higher calcium and manganese content, and consequently of higher thermoresistantes (Amaha and Ordal, 1957). Slepecky and Foster (1959) also showed that the content of individual metals in spores was flexible within a wide range and was dependent on the relative concentration of the particular metal in the growth medium.…”

“…Spores with 'maximal manganese or zinc content possessed minimum calcium, and therefore were thermosensitive. Amaha and Ordal (1957) (Perry and Foster, 1955 ;Collier and Murty, 1957 ;Hashimoto et al, 1960;Church and Halvorson, 1959).…”

Thermal resistance of Bacillus stearothermophilus spores in different heating systems containing some approved food additives

“…It has also been reported for other sporeformers (Walker 1964, Bacillus megaterium;Amaha and Ordal 1957, B. coagulans) that as concentrations of phosphate increase, D-values gradually decrease. Amaha and Ordal (1957) suggested that the higher thermal inactivations observed with increased phosphate concentrations in the heating media were related to the removal of certain cations from spores which contributed to the thermal resistance of spores. The loss rate should be greater in the presence of an increased phosphate concentration since it was also assumed that the phosphate effect was that of a chelating agent.…”