Purification and Some Properties of a Heat-Stable Antibacterial Substance Released from Xanthomonas campestris pv. citri Ku 7101

Abstract

An antibacterial substance which is only effective to homologous isolate was released from bacterial cells of Xanthomonas campestris pv. citri Ku 7101 by heat treatment. The substance was dialyzable through Visking tube and stable to DNase, RNase, Trypsin, Pronase treatment and heating at 120 C for 30min. This substance was eluted from active carbon column by 20-25% ethanol and antibacterial activity of eluates was correlated with intensity of anthrone color reaction. This fraction showed single spot on thin layer chromatogram. The active substance was positive to naphthoresorcinol and sulfuric acid, suggesting that the substance could be mainly composed of sugars.
The antibacterial substance considerably inhibited multiplication of X. campestris pv. citri Ku 7101 in liquid medium and ghost cells were observed with high frequency under electron microscope. The substance, however, was inactive against resting cells in phosphate buffer.