Availability of synthetic media for streptococci.

Abstract

Six hundred and seventy-one synthetic media were tested to determine their availability for streptococci. They may be grouped into three series: (1) those testing the availability of carbon compounds (carbohydrates and related substances, glycerol, and organic acids such as lactic, malic, tartaric and citric); (2) those testing the availability of nitrogen compounds (the common amino acids, caffeine, betaine, urea, and inorganic ammonium salts such as (NH₄)₂CO₃, NH₄Cl, (NH₄)₂ HPO₄); (3) those testing the availability of some inorganic substances (compounds of Ca, Na, K, and Fe, and S). Most of the media were those previously used for other organisms by different investigators. The composition of the media ranged from water solutions of single substances to combinations of ten different materials.

Four hundred and forty-one permitted the streptococci to remain viable through one or more transplants. While it would seem from this, perhaps, that it is a comparatively simple matter to manufacture synthetic mixtures which will permit the growth of these organisms, our results indicate a marked deficiency in all of these media. The significant details may be summarized in the following table in which the figures recorded indicate the number of media showing living organisms in the various subcultures, as explained below :

The symbols, 4+, 3+, 2+, 1+, and the phrase “several colonies,” are used to indicate the amount of growth; 4+ denotes the maximum. The tests on each medium included six transplants. The one from the “test suspension” (consisting of streptococcus growth removed from infusion agar with a spatula and suspended in 0.9 per cent NaCl solution) to the synthetic medium is designated as the first transplant; the five others are successive transplants at 24 hour intervals from synthetic medium to synthetic medium.