DEVELOPMENT OF RESISTANCE TO HEAT AND SODIUM CHLORIDE IN STREPTOCOCCUS FAECIUM RECOVERING FROM THERMAL INJURY

Heating of Streptococcus faecium NRC 1261 at 55 C for 15 min produced injury. The injured population was sensitive to 2.5% NaCl but regained its tolerance when incubated in a recovery medium. Addition of penicillin and actinomycin D to the recovery medium showed that during recovery no cell division occurred and that this recovery was linked to RNA synthesis. Analysis of the fatty acid composition of uninjured and recovered cells by gas liquid chromatography showed an increased concentration of saturated fatty acids in recovered cells. A concurrent increase in resistance to heat shock at 55 C and salt tolerance in these recovered cells occurred with the change in fatty acid composition. It is suggested that a change in membrane structure as reflected by the modified fatty acid profile is related to an increased thermal resistance and salt tolerance.