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Comparison of Nucleic Acids and Other Phosphorus Compounds of Terramycin-Sensitive and -Resistant Strains of Streptococcus Lactis¹

Department of Dairy Technology, The Ohio State University, Columbus

ABSTRACT

Terramycin-sensitive and terramycin-resistant strains of Streptococcus lactis 10A were inoculated in an enriched broth and incubated at 30° C. After 6, 12, and 24 hr. of incubation, determinations were made for total cellular matter, acid-soluble phosphorus, lipid phosphorus, nucleic acid phosphorus, protein phosphorus, and ribonucleic and deoxyribonucleic acids.

The sensitive strain consistently produced more cellular matter than did the resistant strain. The concentrations of the various phosphorus fractions fluctuated during incubation. In general, acid-soluble phosphorus was present in the highest concentrations in cells of both the strains, followed by protein phosphorus, lipid phosphorus, and nucleic acid phosphorus, in that order. At all times, cells of the sensitive strain contained higher concentrations of various phosphorus fractions, except for the acid-soluble fraction, which was present in higher concentration in the resistant cells after 6 and 12 hr. of incubation, and except for the lipid phosphorus content, which was higher in the resistant cells after a 12-hr. incubation period. The ribonucleic acid contents of both cultures were three to four times higher than their deoxyribonucleic acid contents. The total nucleic acid content of the sensitive cells during the earlier stages of incubation was appreciably greater than that of the resistant cells, indicating that the sensitive culture synthesized the nucleic acids more rapidly. However, the total nucleic acid content of the sensitive cells varied widely in different trials. The total nucleic acid content in both the strains decreased after 12 and 24 hr. of incubation, but the extent of decrease in the sensitive strain was more rapid than in the resistant strain, with the result that after 24 hr. of incubation, the total nucleic acid content of both the strains was approximately the same.

¹ Article No. 12: 58 of the Department of Dairy Technology, The Ohio State University. Supported by a grant from the U. S. Public Health Service (National Institutes of Health) and by the Ohio Dairy Products Research Fund.

² Present address: Department of Dairy Husbandry, University of Nebraska, Lincoln.