Bacteriophages

Abstract

Rapid identification and enumeration of the numerically important bacteriophages has been till recently a major limitation for studies of virus ecology. The development of sensitive nucleic acid stains, in combination with flow cytometric techniques, has changed this. The flow cytometric method allows the detection and discrimination of a wide variety of viruses of different morphology, genome type, and size. The present paper describes an optimized protocol for the enumeration of bacteriophages using a standard benchtop flow cytometer.

Anti-phage islands force their target phage to directly mediate island excision and spread

“…Phage were propagated on V. cholerae hosts using the soft agar overlay method 9 . High titer phage stocks were collected by polyethylene glycerol precipitation 22 .…”

Diversity of Sinorhizobium (Ensifer) meliloti Bacteriophages in the Rhizosphere of Medicago marina: Myoviruses, Filamentous and N4-Like Podovirus

“…Four ml of this solution was used to inoculate a fresh set of bacteria as above indicated, finally yielding a solution presumably containing phages. The presence of phages was tested using the double agar overlay plaque assay (Kropinski et al, 2009). Briefly, 100 µl of phage solution were added to 200 µl of middle log-phage S. meliloti strains, the mixture was incubated 5 min at room temperature and then mixed with soft agar to form a lawn on TY solid medium.…”

“…Phage adsorption experiments were carried out as described previously (Hyman and Abedon, 2009), with some modifications. Martínez et al, 1985 S (dark green cell), cases where lysis was complete; s (light green cell), cases where lysis was incomplete or turbid plaques were found; R, absence of lysis.…”

“…Adsorption rates are presented as adsorption constants (k) and are specific for a given phage, host, and physical and chemical adsorption conditions. k = 2.3/Bt•logP 0 /P (ml/min), being B the concentration of bacterial phages, and t the time interval in which the titer falls P 0 (original) to P (final) (Hyman and Abedon, 2009).…”

“…The sensitivity of phages to temperature, pH, and salinity was determined as described by Malek et al (2009), with some modifications. Briefly, phages from a high titer stock were diluted 10 times in SM buffer (Kropinski et al, 2009) at pH 4.5, 7.5 or 8.5 and incubated at 4 • C, 28 • C or 37 • C for 7 days. For the sensitivity to NaCl, phages were also diluted 10 times in SM containing NaCl at concentrations of 300, 600 or 800 mM and incubated as above for 7 days.…”