Use of in vivo 13C nuclear magnetic resonance spectroscopy to follow sugar uptake in Zymomonas mobilis.

A noninvasive, in situ, in vivo, and anomer-specific method for studying membrane transport of sugars in bacteria is presented. High-resolution 13C NMR was used to measure the distribution of alpha- and beta-xylose, maltose, Mes buffer, and ethanol in the extracellular and the cytoplasmic compartments in dense cell suspensions of Zymomonas mobilis, an aerotolerant bacterium that transports xylose but does not further metabolize it. The method relied on a difference in the magnetic susceptibility of the media inside and outside cells, induced with Dy-diethylenetriaminepentaacetic acid. The applicability of this method was demonstrated: (a) by showing that xylose and ethanol crossed the inner membrane of Z. mobilis while maltose and Mes buffer did not and (b) by a kinetic study of xylose uptake in this organism. After addition of xylose, both the extracellular decrease in the alpha- and beta-anomers in the medium and their intracellular accumulation could be followed.