SUMMARY: The properties of three additional hosts for the high frequency transducing (HFT) phages 5006MHFT and 5006MHFT are described. The phages transduce resistance to kanamycin and to ampicillin plus kanamycin, respectively, and were produced by ultraviolet induction of derivatives of strain PM5006. Strain PM804 could not be shown to adsorb the phages although it yielded a few transductants. All transductants, even those produced at low multiplicities of phage input, were lysogenic and segregated markers at high frequency. Ultraviolet induced phage lysates of these transductants transduced PM804 at higher frequencies and PM5006 at lower frequencies than the original phages. Strain PM804 or its derivatives did not adsorb phage from these lysates. Transmission experiments through PM5006 of phage in the transductant lysates confirmed that PM804 had a host-controlled modification system which modified HFT phage from PM5006. That PM804 also possessed a restriction system was inferred from the greater numbers of transductants obtained with phage which bore a compatible modification pattern. Strain N and a restrictionless mutant of it named NHI, adsorbed the HFT phages avidly and failed to modify their host range. Transduction frequencies of the phage markers were about 10/p.f.u. adsorbed to strain NHI and only about tenfold lower to strain N which did not plate the phages. Transductants also had the features of heterogenotes and those obtained at low multiplicities of infection were non-lysogenic. The latter transductants adsorbed homologous phage while NHI transductants also plated the HFT lysates. Strain NHI, lysogenized by the parent phage 5006M, did not adsorb the HFT phages. These findings suggest that the HFT phages were most likely defective for lysogenic conversion to homologous phage non-adsorption. The postulated restriction enzymes of PM804 and strain N could not be shown to be thermolabile.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error