AbstractŠpelina V., Schlemmerová L., Landfeld A., Kýhos K., Měřička P., Houška M. (2007): Thermal inactivation of Enterococcus faecium. Czech J. Food Sci., 25: 283-290.Data for thermal inactivation of working suspension of Enterococcus faecium in model solutions were acquired and used to develop a mathematical model for thermal inactivation of the bacterium. The model is valid within the water activity range 0.97 to 0.99; pH range 6.0 to 7.6; temperature range 60°C to 65°C, and was determined for the microorganism concentration ranges of 10 2 per ml to 10 8 per ml of the model inactivation solution. An Excel procedure was developed in Visual Basic language which enables the calculation of the final concentration of the microorganism from the input data for pH, a w , logN 0 , temperature, and holding time of the treatment. The proposed model was verified in experiments using cow and human milks. With cow milk, the correspondence between the experimental and the predicted data is highly satisfactory. With human milk, the model predicts a smaller effect of heating than is that manifested experimentally.

that the DNA transferred during conjugation is synthesized during mating under separate control in the male cell. This theory is based on the reports of K. W. Fisher (J. Gen. Microbiol. 16:120 and 16:136, 1957) that the female is not actively involved in the replication and transfer of the penetrating chromosome. From experiments of F. Bonhoeffer (Z. Vererbungslehre 98:141, 1966), it was concluded that the transfer of chromosome was not affected when deoxyribonucleic acid (DNA) synthesis was prevented in a thermosensitive mutant of an Hfr strain of Escherichia coli. However, the inhibition of DNA synthesis in the female resulted in the inhibition of recombinant formation. D. Freifelder (J. Bacteriol. 94: 396, 1967) observed that purine-requiring female strains of E. coli starved for purine formed mating pairs with the male cells, but the yield of recombinants was markedly reduced. From this, it was presumed that the mating process resulting in formation of recombinants requires some active function of the recipient cell. This function is as yet unknown, since purine starvation inhibits DNA, ribonucleic acid, and protein synthesis, and reduces all metabolic processes where adenosine triphosphate is involved. This report shows that the yield and the rate of recombinants formed by mating of synchronized female cells of E. coli depends on the position of recipient cells in the division cycle. The following strains of E. coli were used in synchronization experiments and in genetic crosses: HfrC, Met-; 242, F-Pro-Lac Strc (a