Abstract
Some properties of temperate coliphage φ81 were studied in comparison with those of phages φ80 and λ. Plaque morphology, latent period, and immunity characteristics of this phage are distinct from those of φ80 and λ. In contrast to λ, φ81 as well as φ80 is unable to form plaques at 42 °, but phage particle itself is resistant to heat treatment at 60 ° for 30 min. Heteroimmune curing was observed between φ81 and λ. Genetic mapping has located the prophage site ( att81) between galactose and biotin markers on the Escherichia coli chromosome, the probable gene order being gal- att81- attλ- bio. Phage φ81 was found to transduce specifically the galactose and biotin genes at a frequency of 10 −6 to 10 −7 and 10 −7 to 10 −8, respectively, per plaque-forming unit (low frequency transduction, LFT). Some of the Gal + transductants obtained produced high frequency transducing (HFT) lysates upon induction, and were often unstable and segregated out Gal − clones at high frequency. Gal + transducing phages that are capable of forming plaques (φ81 pg) were obtained from one of these transductants. Buoyant density of gal + transducing phage studied almost coincided with that of plaque-forming phage φ81.
Published Version
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