OCCURRENCE OF A TEMPERATE CYANOPHAGE LYSOGENIZING THE MARINE CYANOPHYTE PHORMIDIUM PERSICINUM¹

Abstract

A temperate cyanophage was found to lysogenize the marine cyanophyte Phormidium persicinum (Reinke) Com. (Provasoli strain). The lytic cycle was induced by the addition of mitomycin C or by brief illumination with ultraviolet light. The lytic process observed under the electron microscope showed that phage particles appeared in a nucleoplasm region 15 to 24 h after the addition of mitomycin C. The induction of the lytic process occurred simultaneously in almost all cells of every trichome. Matured phage particles were released to the medium 30 to 50 h after the addition of mitomycin C. Phage particles isolated from algal lysates had a polyhedral head (about 40 nm in diameter) with a long (about 300 nm) and noncontractile tail. The most abundant protein, presumably a structural protein, had an apparent molecular mass of about 38 kDa. The genome size estimated from restriction analysis was about 50 kbp. Phage DNA was digested with several restriction endonucleases including Sau3AI and DpnI. However, MboI failed to digest the phage DNA, suggesting that the phage DNA is highly methylated. Southern blot analysis suggested that some part of the phage was in the lytic cycle in algal cells growing under normal conditions. A possible role of temperate cyanophages in the regulation of cyanophyte populations in the marine environment is discussed.

Virus-like particles associated with Lyngbya majuscula (Cyanophyta; Oscillatoriacea) bloom decline in Moreton Bay, Australia

“…The tail structure of the L. majuscula virus is substantially shorter than the temperate cyanophage of Phormidium persicinum (Ohki & Fujita 1996), another marine filamentous cyanobacteria with a Cyanostylovirus cyanophage.…”

“…In particular, the understanding of L. majuscula host-cell resistance dynamics and decay rates of cyanophage under bloom conditions is essential to the complete understanding of the role of cyanophage in bloom dinsintegration. (Ohki & Fujita 1996) …”

“…(Suttle & Chan 1993). Few cyanophages specific to macroscopic, filamentous cyanobacteria have been identified (Ohki & Fujita 1996, Ohki 1999. Only temperate cyanophages that remain within the host genome until induced by environmental stimuli (Wilson & Mann 1997) have been reported in marine non-heterocystous cyanobacteria.…”

“…Only temperate cyanophages that remain within the host genome until induced by environmental stimuli (Wilson & Mann 1997) have been reported in marine non-heterocystous cyanobacteria. Ohki & Fujita (1996) isolated a temperate cyanophage specific to the tropical cyanobacterium Phormidium persicinum, while Ohki (1999) isolated a temperate phage specific to Trichodesmium spp. The isolation of these cyanophages has caused review of the role of viruses in the demise of cyanobacterial blooms (Suttle 2000).…”

Lysogenic and lytic viral production in marine microbial communities

“…It is known that many bacteriophages occurring in aqueous environments are temperate. Approximately 4 % of Escherichia coLi isolates from sewage and faeces are lysogenic (Dhillon & Dhillon 1981) as are many strains of lactic acid streptococci used in cheese making (Jarvis et al 1978) and a temperate bacteriophage has been recently isolated which lysogenizes the marine cyanobacterium Phormidium persicinurn (Ohki & Fujita 1996).…”