ANOMALOUS UPTAKE OF D-RIBOSE BY RHODOTORULA GRACILIS

d-Ribose was found to enter the cells of Rhodotorula gracilis by a mechanism resembling simple diffusion (proportionality between rate and concentration, no effect of inhibitors, of temperature, of other sugars) at concentrations from 0.001 to 10 mm. With a lag of about 1 hour, d-ribose was oxidized and, with a lag of about 20 hours, it could serve as a growth substrate. The transport step appears to be rate-limiting for the subsequent metabolic processes. The oxidation was stimulated by d-xylose but unaffected by d-glucose. © 1969 Institute of Microbiology, Academy of Sciences of the Czech Republic.