THE EFFECT OF WHEAT-GERM-AGGLUTININ ON DINITROGEN FIXATION, GLUTAMINE-SYNTHETASE ACTIVITY AND AMMONIA EXCRETION IN AZOSPIRILLUM-BRASILENSE SP-245

Wheat germ agglutinin was found to increase glutamine synthetase and nitrogenase activities and excretion of N2-fixation product (NH4+) in Azospirillum brasilense Sp 245. Each effect had a similar pattern and correlated well with each other. They were dynamic, had maxima in the middle of the exponential phase of growth, and were due to N-acetyl-D-glucosamine specificity of wheat germ agglutinin, since its preincubation with 10% N-acetyl-D-glucosamine caused the disappearance of the effects. When wheat germ agglutinin was replaced with Ulex europaeus agglutinin II possessing the same carbohydrate binding specificity all the above effects remained, replacing wheat germ agglutinin with concanavalin A with a different sugar specificity, or with bovine serum albumin led to their disappearance.