Aerobic Utilization of Low Concentrations of Galactose by Lactobacillus plantarum

SUMMARY: galactose was 44 for Lactobacillus plantarum grown aerobically in defined medium containing 1 to 6 μmol galactose/ml. Nevertheless, 93 % of the galactose was converted to acetate, and the Y ATP was 11·3. Yields were not appreciably less if 0·5% acetate or 1·0 10-4 M arsenite was added to the medium, but they were considerably lower if riboflavin was omitted. Lactobacillus plantarum, subsequent to converting low concentrations of hexose to pyruvate by the Embden-Meyerhof-Parnas pathway, can apparently gain, under aerobic conditions, approximately two additional mol ATP/mol hexose by converting most of the pyruvate to acetate. Lipoic acid and coenzyme A were not involved in the production of acetate; riboflavin was involved in the utilization of oxygen as an electron acceptor.