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Antibiotic Influence on Arginine Desimidase Activity by Streptococcus Lactis¹

Department of Dairy Technology, The Ohio State University, Columbus

ABSTRACT

The antibiotic influence on the rate of arginine desimidase activity by Streptococcus lactis 10DS was studied by a colorimetric technique which utilized Bacto-Decarboxylase Base Broth (Difco), modified by the addition of 0.5% L-arginine · HCl and containing bromcresol purple indicator. The bromcresol purple indicator permitted visual observation of the rate of acid production and arginine hydrolysis, the latter producing an alkaline reaction. Within a 12.5-hr incubation period at 30 C, the following antibiotic concentrations/milliliter were found to suppress arginine desimidase activity: 0.005 µg oxytetracycline or chlortetracycline, 0.005 unit penicillin, 0.5 unit nisin, 0.075 µg oleandomycin, 0.005 unit bacitracin, 0.01 µg streptomycin, 7.5 units polymyxin, and 0.1 µg neomycin. Arginine desimidase activity in S. lactis cells was much more sensitive to antibiotics than the enzymes required for acid production.

A simple antibiotic assay procedure is proposed which utilizes S. lactis 10DS organism and arginine-enriched broth.

¹ Article 12:65. Department of Dairy Technology, The Ohio State University. This investigation was supported in whole by Public Health Services Grant No. EF 00101 from the Division of Environmental Engineering and Food Protection.