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Abstract

The number of successful propagations/isolations of soil-borne bacteriophages is small in comparison to the number of bacteriophages observed by microscopy (great plaque count anomaly). As one resolution of the great plaque count anomaly, we use propagation in ultra-dilute agarose gels to isolate a Bacillus thuringiensis bacteriophage with a large head (95 nm in diameter), tail (486 × 26 nm), corkscrew-like tail fibers (187 × 10 nm) and genome (221 Kb) that cannot be detected by the usual procedures of microbiology. This new bacteriophage, called 0305φ8-36 (first number is month/year of isolation; remaining two numbers identify the host and bacteriophage), has a high dependence of plaque size on the concentration of a supporting agarose gel. Bacteriophage 0305φ8-36 does not propagate in the traditional gels used for bacteriophage plaque formation and also does not produce visible lysis of liquid cultures. Bacteriophage 0305φ8-36 aggregates and, during de novo isolation from the environment, is likely to be invisible to procedures of physical detection that use either filtration or centrifugal pelleting to remove bacteria. Bacteriophage 0305φ8-36 is in a new genomic class, based on genes for both structural components and DNA packaging ATPase. Thus, knowledge of environmental virus diversity is expanded with prospect of greater future expansion.

Things Are Getting Hairy: Enterobacteria Bacteriophage vB_PcaM_CBB

“…When the phage was plated and examined by plaque assay utilizing a 0.4% agar overlay, pinpoint sized plaques were observed with inconsistent formation across replicate experiments. This problem was overcome by using a 0.2% agarose overlay as described by Serwer et al (2007). The host range of the phage was examined using a number of bacterial genera and species within the family Enterobacteriacea which showed it was capable of forming plaques on strains of P. carotovorum, Pectobacterium atrosepticum, Erwinia mallotivora, Cronobacter muytjensii , and Cronobacter malonaticus .…”

“…The phage double overlay assay was conducted using overlays containing 0.2% agarose for morphologically large phage as described by Serwer et al (2007). Stocks of phage were produced according to the plate lysis method described by Sambrook and Russell (2001a).…”

Bacteriophage Ecology in a Commercial Cucumber Fermentation

“…500 kb), is unable to form plaques under normal conditions due to its large virion size (13,14). Bacillus thuringiensis phage 03058-36, another large phage, forms plaque only in ultradilute agarose gels (34). Phage 03058-36 does not propagate in the traditional gels used for phage plaque formation and also does not produce visible lysis of liquid cultures.…”

Identification of Essential Genes in the Salmonella Phage SPN3US Reveals Novel Insights into Giant Phage Head Structure and Assembly

“…For many years, giant phages were considered elaborate oddities of little general relevance due to their perceived rarity (1). However, this viewpoint has changed radically in the last decade with the realization that standard phage isolation techniques were biased against larger phages and that giant phages can be readily isolated from a diversity of environmental samples (3–5). The first giant phage genome sequenced was the 280-kb genome of Pseudomonas aeruginosa ϕKZ (2).…”