High speed marine bacteria use sodium-ion and proton driven motors

The ocean's strong ionic environment may be important for motility in marin e bacteria. This is because flagellar motors are powered by dissipation of ion gradients across their cell membranes. We tested how much the 2 known m otor systems contributed to the high speed motility (>100 mu m s(-1)) found in marine bacterial communities and isolates. Monensin, carbonylcyanide-m- chlorophenylhydrozone (CCCP) and amiloride were used on Escherichia coli, S hewanella putrefaciens, Alteromonas haloplanktis, a marine isolate (BBAT1) and marine bacterial communities to uncouple sodium-ion and proton gradient s from motility. E. coli motility was stopped by 10 mu M CCCP. Use of any o f the 3 uncouplers alone slowed, but did not stop, S. putrefaciens, A. halo planktis and a community of marine bacteria. A combination of 20 mu M CCCP and 20 mu M monensin stopped S. putrefaciens and A. haloplanktis. The same concentration combination reduced marine community speeds by half, but stop ped few cells. Above uncoupler concentrations of 30 mu M speed remained unc hanged at about 20 mu m s(-1) for marine bacterial communities. Sodium-ion motors were responsible for about 60% of marine bacterial speed. From the r esults it was concluded that most high speed marine bacterial community mem bers used sodium and proton motors simultaneously.