Nitrogen Requirements of the Lactic Acid Bacteria

Abstract

IN view of the importance attached by Orla-Jensen to the nitrogen source employed in the study of the lactic acid bacteria—an importance emphasised by the results of our own studies—we have investigated the nitrogen distribution in some thirty-seven sources of nitrogen, and have determined the influence of these sources on the production of acid from glucose, mannose, and lactose by five strains of lactic acid streptococci after fourteen days' incubation at 23° C. For the nitrogen distribution determinations we used the method of Wasteneys and Borsook. In the subsequent preparation of the sugar broths for the fermentation work and in the recording of the results we proceeded after the manner of Orla-Jensen. Certain of the nitrogen sources investigated are available commercially many, principally peptic, digests of casein and some tryptic digests of casein, are such as may readily be prepared by laboratory workers.