CARRIER-MEDIATED ACETATE UPTAKE IN CORYNEBACTERIUM-GLUTAMICUM

Acetate is effectively taken up by whole cells of Corynebacterium glutamicum via a specific carrier with a pH optimum of 8. The K(m) of acetate uptake was 50-mu-M and the V(max) 25-35 nmol/mg dw min. The activation energy was determined to be 70 kJ/mol. Acetate uptake was competitively inhibited by propionate with a K(i) of about 30-mu-M and blocked by addition of sulfhydryl reagents. The transport activity was clearly dependent on the membrane potential, but independent of the presence of Na+-ions. It is concluded that uptake of acetate proceeds by a secondary, proton coupled mechanism.