Some observations on the physiology of Erwinia herbicola and its possible implication as a factor antagonistic to Erwinia amylovora in the "fire-blight" syndrome

Erwinia herbicola, which is often associated with E. amylovora in "fire-blight" diseased tissues, possesses a β-glucosidase which cleaves arbutin to yield hydroquinone and D-glucose. Hydroquinone accumulated in cultures of E. herbicola grown on arbutin broth to a concentration of ca. 1000 μg/ml after 24 hours. Accumulation of hydroquinone occurred to a much lesser extent in E. amylovora cultures. Hydroquinone inhibited the oxidative metabolism of D-glucose by E. amylovora, but not by E. herbicola. The implication of these observations to the development of the "fire-blight" syndrome is discussed.