INDUCTION OF TEMPERATE CYANOPHAGES USING HEAVY METAL - COPPER

Abstract

Presence of prophages in cells of three isolates of Anabaena sp. (Anabaena sp.1, sp.2 and sp.3), Anabaena cylindrica, Nostoc muscorum and Oscillatoria sp. was investigated. Copper sulfate at concentration of 3.1x10-4 M was successfully used for induction of temper-ate cyanophages. Among the cyanobacterial isolates tested Anabaena cylindrica was found to contain a prophage. A temperate phage was induced from Anabaena cylindrica by copper sulfate treatment and designated Ac-1. The induced phage isolate formed hazy circular plaques of 5 mm in diameter. The thermal inactivation point and longevity in vitro of the induced phage isolate (Ac-1) were found to be 70°C and 36 hrs., respectively. The induced cyanophage particles were examined by transmission electron microscopy. The phage particles were of head and tail type. The head diameter, tail length and tail width were found to be 50 nm, 116.6 nm and 8.3 nm, respectively. Ultrathin sections of infected A. cylindrica cells with temperate cyanophage and healthy ones were examined by electron microscopy. Marked changes in protoplasm and cell membrane, i.e. coagulation of protoplasm, formation of vesicles and vacuoles were observed in the infected cells as compared to the healthy ones. Phage particles were detected inside the infected A. cylindrica cells. Moreover, lysis of cell wall and release of the induced phage particles were also observed.