The nitrogen content of the pneumococcus

Abstract

A study of the nitrogen content of various bacterial groups and subgroups was undertaken by the writers some months ago. The object was to determine, if possible, the relationship of the nitrogen content which might occur between members of a single group, and also that between the subgroups of a species where such are known to exist. While progress has been made in this study, much remains to be done, and we are continuing the investigation. A preliminary report of the results of our analyses made upon the pneumococcus, including the four serological subgroups, may prove to be of interest to others. We therefore submit some of the data, although the study is not completed.

Recognizing the many known factors which may enter and alter the results in a study of the protein content of bacteria, we have attempted to control these factors in so far as possible by keeping them constant throughout. In this way, to a certain degree, a comparison is possible between the derived chemical data.

The organisms used in this study were for the most part recovered from sputum, blood, etc., of patients in St. Luke's Hospital, although we are indebted to Dr. Avery, of the Rockefeller Institute, and to Dr. Wadsworth, of the New York State Health Department Laboratories, for a few strains of the Type II. In each instance the identity of the organism was established by its characteristic morphology, staining properties, bile solubility, and reaction to specific immune serum. Ten strains of each of the four chief groups were cultured in flasks containg about 75 c.c. of a beef infusion broth containing one per cent. of dextrose, and having an average reaction of P_H 7.4 to 7.6. Usually sufficient growth for the purpose of the study was produced within 21 hours, when incubated at 36° or 37° C.