Substrate selection as a possible strategy for amelioration of acid pH by Rhizobium leguminosarum biovar viciae

A possible mechanism for bacteria to ameliorate an unfavorably acidic exter nal pH would be to select for catabolism of those substrates in a mixture t hat would alkalinize the medium. This hypothesis was tested with cultures o f Rhizobium leguminosarum biovar viciae WSM710 grown at pH 7.0 or 5.5 on bi nary mixtures of glucose plus fumarate or glucose plus histidine. The resul ts showed no significant increase in the absolute or relative utilization o f the alkalinizing substrates (fumarate or histidine) at pH 5.5. (C) 2000 E lsevier Science Ltd. All rights reserved.