HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mikolajcik, E. M. Search for Related Content PubMed Articles by Mikolajcik, E. M.

Single Broth for the Differentiation of Streptococcus lactis from Streptococcus cremoris¹

Department of Dairy Technology, The Ohio State University, Columbus

ABSTRACT

Routinely, the Streptococcus lactis species is distinguished from Streptococcus cremoris by the following: ability to grow at 40 C, production of ammonia from arginine, fermentation of maltose and dextrin, and growth in 4% NaCl broth and at a pH of 9.2 (1). This conventional differentiation is somewhat complex and cumbersome, requiring the preparation of various broths and indicators and the use of two different incubation temperatures. In contrast, the procedure herewith presented is comparatively simple and direct, utilizes only one medium and a single incubation temperature, and is based on the principle that organisms belonging to the species S. lactis will decarboxylate arginine, whereas those classified as S. cremoris will not.

Briefly, the method is as follows: Decarboxylase base medium (Difco, 0872) containing brom cresol purple indicator is fortified with 0.5% L-arginine. One-tenth milliliter of an active 16-18-hr skimmilk culture is used to inoculate 5-ml quantities of arginine decarboxylase broth contained in tightly capped screwtop tubes.

¹ Article 4:64. Department of Dairy Technology, The Ohio State University. Supported by a grant from the U. S. Public Health Service (National Institutes of Health).