CONTROL OF FIRE BLIGHT WITH A LYSOZYME FROM THE ERWINIA AMYLOVORA PHAGE EA1HCONTROL OF FIRE BLIGHT WITH A LYSOZYME FROM THE ERWINIA AMYLOVORA PHAGE EA1H

Abstract

A lysozyme gene from Erwinia amylovora phage Ea1h was cloned and expressed in Escherichia coli, and the protein activity compared with lysozyme from E. coli phage T4. Ea1h lysozyme lysates strongly affected E. amylovora cells. The protein displayed enzymatic and antibacterial activities. The lytic function could be destroyed by heat treatment of lysates, which still formed inhibition zones after boiling on agar plates and showed enhanced growth inhibition of bacterial cultures. According to recent data, the antibacterial activity of lysates with Ea1h lysozyme can be explained with kanamycin bound to high molecular weight cell components. This agrees with findings that growth of bacterial strains carrying kanamycin-resistance was not inhibited, in contrast to all other tested E. amylovora strains and other Gram-negative bacteria, which were highly sensitive to lysates with Ea1h lysozyme. Similarly, pear slices soaked in Ea1h lysozyme-containing cell lysates showed reduced fire blight symptoms after inoculation with E. amylovora. The T4 lysozyme mainly affected the growth of Gram-positive bacteria. The Ea1h lysozyme gene has been expressed not only in tobacco but also in an apple cultivar with the aim to enhance the resistance against fire blight.