Bacteriophage X-2: a Filamentous Phage Lysing IncX-Plasmid-harbouring Bacterial Strains

Abstract

Phage X-2, a filamentous rod about 950 nm in length, was isolated from sewage as plating on strains of Escherichia coli, Salmonella typhimurium or Serratia marcescens carrying either the IncX plasmid R6K, or the unique plasmid R775. Phage X-2 differs morphologically from a previously described very broad host range filamentous phage X which also lyses plasmid R6K-carrying strains and the phages differ in their resistance to inactivation by diethyl ether. Phage X-2 is serologically unrelated to phage X and the X-like phages IKe and 12-2. The adsorption site of the phage on the plasmid-bearing strains could not be determined but evidence implicating conjugative pili is presented.

Expansion of the IncX plasmid family for improved identification and typing of novel plasmids in drug-resistant Enterobacteriaceae

“…IncX plasmids have been isolated from Enterobactericeae dating back to the pre-antibiotic era (Jones and Stanley, 1992). These plasmids are iteron-containing plasmids with theta replication, thought to be of narrow host range (Stalker and Helinski, 1985), and were first identified based on their ability to confer sensitivity to filamentous bacteriophage (Brown et al, 1999;Coetzee et al, 1988). Beyond their isolation most commonly in species such as Escherichia coli and Salmonella enterica, IncX plasmids have been shown to be transferrable from E. coli to Pseudomonas aeruginosa (Tardif and Grant, 1983) suggesting that their host range might be greater than previously appreciated.…”

Salmonella Pathogenicity and Host Adaptation in Chicken-Associated Serovars

“…In addition to enhancing the excision of chromosomal islands, these plasmids may also harbor receptor sites for phage recognition. For example, plasmids such as IncN and IncX have been shown to convert phage types among Salmonella strains (160,161), and IncX plasmids seem to harbor phage recognition sites (162). Thus, when considering the role of plasmids in genome evolution, it is important to consider not only the accessory gene repertoire that they carry but also the modulations that they confer to the Salmonella host.…”

Plasmid R6K Contains Two FunctionaloriTswhich can Assemble Simultaneously in Relaxosomesin vivo

“…Phages used were X-2 (Coetzee et al, 1988) and lTn5tac1 (Chow & Berg, 1988). Plasmids are listed in Table 1.…”