A Differential Medium for the Enumeration of Homofermentative and Heterofermentative Lactic Acid Bacteria
Abstract
A Differential Medium for the Enumeration of Homofermentative and Heterofermentative Lactic Acid Bacteria † L. C. Mc Donald , R. F. Mc Feeters * , M. A. Daeschel and H. P. Fleming Food Fermentation Laboratory, Agricultural Research Service, U.S. Department of Agriculture, and Department of Food Science, North Carolina Agricultural Research Service, North Carolina State University, Raleigh, North Carolina 27695-7624 ABSTRACT A medium was developed for the differential enumeration of homofermentative and heterofermentative lactic acid bacteria. Essential components of the medium included fructose (14 mM), KH 2 PO 4 (18 mM), bromcresol green (as a pH indicator), and other nutrients to support growth. In agar medium, homofermentative colonies were blue to green, while heterofermentative colonies remained white. A total of 21 Lactobacillus, Pediococcus, Leuconostoc, and Streptococcus species were correctly classified with the medium.