Study of plating efficiency of bacteriophages of thermophilic lactic acid bacteria on different media.

The qualitative and quantitative abilities of phages of 13 strains of thermophilic lactic bacteria (lactobacilli and streptococci) to produce plaques on six different media were studied. The influence of the addition of calcium on the one hand, and of incubation conditions (aero-anaerobiosis), on the other hand, was also examined. For the phages of lactobacilli, the best results were obtained with the medium of de Man, Rogosa, and Sharpe (1960), whereas for the phages of streptococci the medium of Hogg and Jago (1970) appeared to be the best. Calcium and incubation conditions play a role which is variable in importance, but rarely negligible.