CULTURE IN THE PRESENCE OF SUGARS INCREASES ACTIVITY OF MULTIDRUG EFFLUX TRANSPORTER ON HALOFERAX-VOLCANII

We found that when a growth medium contained glucose, wild-type cells of Haloferax volcanii were able to grow even in the presence of doxoru bicin (DOX), an anti-cancer reagent, whereas they usually cannot grow in its presence. The reason was that cells grown in the presence of gl ucose (glucose-grown cells) showed high multi-drug efflux activity eve n though the growth medium contained no DOX or substrates of the trans porter. This transporter was ATP-driven and the elevation of efflux ac tivity was not due to an increase in intracellular ATP contents. The a ctivity was increased not only by glucose but also by sugars that coul d be metabolized.