CULTURAL STUDIES ON STREPTOCOCCUS DIACETILACTIS AND OTHER MEMBERS OF THE LACTIC STREPTOCOCCUS GROUP

Abstract

Cultural information about Streptococcus diacetilactis strains is tabulated along with similar data on Streptococcus lactis, Streptococcus cremoris, and certain Leuconostoc species. These data facilitate comparisons of bacteria commonly found in mixed-strain lactic starter cultures. Characteristic reactions which indicate simple means of differentiating between these organisms may be observed. The data are used to justify the recognition of S. diacetilactis as a third species of the lactic streptococcus group. Leuconostoc organisms are separated into two groups on the basis of dextran production on a sucrose medium.Details of a manometric method for measuring CO₂production by single and mixed-strain starter cultures are given. The Warburg Respirometer was employed for this purpose and possible application of the method in the design of mixed-strain starter cultures for use in the dairy industry is discussed.