The Nutritional Requirements of Lactic Streptococci Isolated from Starter Cultures. I. Growth in a Synthetic Medium

Abstract

A nutritional investigation of 35 strains of 8. lactis and S. cremoris isolated from commercial starter cvdtures show that they required proline, isoleucine, valine, leucine, histidine, glutamine, and methionine, and all except one required arginine. Cystine, tryptophane, aspartic acid, and serine were not required for growth of any of the strains investigated. All of the other amino acids were required by one or more of the strains in order to initiate growth. Glutamic acid could substitute for glutamine in 10 of the 35 strains studied. Niacin, pantothenic acid, and biotin were required for growth by all of the strains investigated. Pyridoxine and thiamin were necessary in all eases for maximum response. The requirement for riboflavin was varied. Most of the strains were stimulated and more than one-third required it for growth. Liver fraction L markedly stimulated the rate of initial growth of all strains of S. lactis and S. cremoris studied. The effect was especially pronounced in the case of the slow strains. © 1953, American Dairy Science Association. All rights reserved.