The effect of various proteins on streptolysin production

Abstract

Variations in streptolysin production in horse and rabbit serum media were noted in a previous publication. In horse serum hemolysin was produced in titratable quantities later in the growth of cultures than in rabbit serum broth but the maximum concentration reached was greater. Unless glucose were present the curve of lysin production corresponded closely to that of growth since hemolysin was found in greater concentration during the period in which the bacteria were multiplying most rapidly. On account of these differences which were characteristic of these sera an attempt was made to discover the responsible factors. The albumen and globulin ratio was modified so that the horse serum contained the same proportions of horse-serum albumen and globulin as were found in rabbit serum, and rabbit serum the same percentages as were present in horse serum. Flasks prepared with 20 per cent. of these modified sera in plain infusion with 0.7 per cent. NaCl, were seeded with equal quantities of a 16-hour culture of hemolytic streptococcus in 20 per cent. horse serum broth. Hemolysin titrations were then made at intervals of an hour with a suspension of horse corpuscles in physiological salt.

The percentages of albumen and globulin in normal rabbit and horse sera were determined by fractioning the diluted serum with ammonium sulfate. The analyses in parts per hundred were as follows:

Sterile albumen and globulin were obtained respectively from horse and rabbit sera under sterile conditions. The albumen was precipitated with ammonium sulfate. The globulin was prepared by saturating diluted rabbit serum with CO₂ and so did not represent the true globulin fraction of the serum.

The horse serum was diluted until it contained 2.27 grams of globulin per hundred C.C. and sufficient horseserum albumen added to bring the percentage of albumen to 3.41 grams per cent.