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Nonutilization of Beta-Glucosides for Growth by Fluorescent Pseudomonads. J. J. Joubert, Assistant Research Plant Pathologist, Department of Plant Pathology, University of California, Berkeley 94720, Present address of senior author: Department of Plant Pathology and Microbiology, University of Natal, Private Bag 9021, Pietermaritzburg, South Africa; D. C. Hildebrand(2), and M. N. Schroth(3). (2)(3)Associate Research Plant Pathologist, and Associate Professor, respectively, Department of Plant Pathology, University of California, Berkeley 94720. Phytopathology 60:502-505. Accepted for publication 20 October 1969. DOI: 10.1094/Phyto-60-502.

Although Pseudomonas syringae hydrolyzed large amounts of glucosides such as arbutin and salicin, the hydrolysis products were not utilized for growth. The maximum amount of growth in media containing 0.01, 0.04, and 0.1% glucose was correlated with the glucose present. The addition of 1-2% of a glucoside had no influence on growth, although nearly complete hydrolysis of the glucoside occurred. Growth was supported by the hydrolysis products of glucosides hydrolyzed by almond beta-glucosidase. Oxygen uptake was very slight with arbutin as a substrate (< 3.0 µliter O2/µmole substrate per hr maximum compared with > 60 µliter/hr with glucose). Only trace amounts of glucose were formed during hydrolysis, and inorganic phosphate was not required. Also, cell-free extracts hydrolyzed nonphosphorylated glucosides. These data indicate that the pseudomonad beta-glucosidase system is different from that occurring in the Enterobacteriaceae.