Most other lactic acid bacteria transport lactose into the cell as lactose using a permease. These organisms hydrolyse lactose to glucose and galactose using a beta-galactosidase; galactose is converted to glucose-6-phosphate by the Leloir pathway and thus into the glycolytic pathway. Streptococcus thermophilus metabolises 1 mol lactose to 2 mol L-lactate since they metabolise only the glucose moiety of the disaccharide. Certain species of lactobacilli produce D- or DL-lactate, depending on the type of lactate dehydrogenase they possess. Leuconostoc sp. use a different sequence of biochemical events for lactose metabolism; the end products of phosphoketolase pathway are quite different (1 mol lactose is converted to 2 mol D-lactate, 1 mol ethanol and 2 mol CO2) to those of glycolysis.
Fox, P.F., T.P. Guinee, T.M. Cogan and P.L.H. McSweeney (2000). Fundamentals of Cheese Science. Aspen Publishers, Gaithersburg, MD. 587 pp