β-Glucosidase Activity in Phytopathogenic Bacteria

Abstract

Most of 58 isolates of phytopathogenic and related bacteria comprising 24 species in the genera Agrobacterium, Erwinia, Corynebacterium, Pseudomonas , and Xanthomonas exhibited β-glucosidase activity, especially the gall-nonforming pathogenic pseudomonads and soft rot organisms. The gall-forming pseudomonads and P. fluorescens exhibited no β-glucosidase activity, with the exception of one isolate of P. savastanoi which showed slight activity on an inorganic nitrogen-arbutin medium. The best medium for demonstrating β-glucosidase activity contained peptone as the nitrogen source and arbutin. β-Glucosidase activity in this medium was indicated by either acid production or browning. P. syringae , in contrast to other bacteria tested, produced most β-glucosidase in a medium containing large amounts of glucose. Chromatographic analyses confirmed that splitting of the glucoside occurred at the glucosidic linkage. Reaction of sonically treated bacterial cells with indican or p -nitrophenyl-β-D-glucoside proved a rapid method for assaying relative amounts of β-glucosidase among bacterial species. Harda's paper-strip method of detecting β-glucosidase also was useful in revealing the distribution and relative amounts of β-glucosidase in most bacteria, but did not indicate the relatively greater amount of β-glucosidase in P. syringae .