Related Experiment Videos
Transduction of a Proteus vulgaris strain by a Proteus mirabilis bacteriophage
Abstract:
Only Proteus vulgaris strain PV127 out of many P. vulgaris, P. morganii and Providence strains was transduced to kanamycin resistance by high-frequency transducing variants, 5006MHFTk and 5006MHFTak, of phage 5006M, a general transducing phage for P. mirabilis strain PM5006. The phages adsorbed poorly to strain PV127 and did not form plaques. The transduction frequency of PV127 by these phages was 5 x 10(-8)/p.f.u. adsorbed. Phage 5006M increased the transduction frequencies. Abortive transductants were not detected. Transductants segregated kanamycin-sensitive clones at high frequency and this, together with data from the inactivation of transducing activity of lysates by ultraviolet irradiation, indicated that transduction was by lysogenization. The general transducing property of the phages was not expressed in transductions to auxotrophs of PV127. Transductants (type I) resulting from low multiplicities of phage input adsorbed phage to the same extent as PV127. This suggested a defect in the transducing particles (or host) because single phage 5006M infection converted strain PM5006 to non-adsorption of homologous phage. Type I transductants did not liberate phage, suggesting a defective phage maturation function. Transductants (type II) which arose from higher multiplicities of phage input did not adsorb phage, indicating possible heterogeneity among transducing particles. Phage derived from type II transductants adsorbed poorly to PV127 and transduced it to kanamycin resistance at frequencies similar to those of phages 5006MHFTk and 5006MHFTak, ruling out host-controlled modification as a cause of the low transduction frequencies. This phage transduced PM5006 to antibiotic resistance at high frequencies but generalized transduction was again not detected. It was suggested that general transduction could be performed by particles which, due to a different composition and/or mode of chromosomal integration, made material they carried susceptible to host-cell modification.
Insights
High-frequency transducing phage variants enabled kanamycin resistance in Proteus vulgaris strain PV127. Transduction occurred via lysogenization, with distinct transductant types revealing phage maturation defects and potential heterogeneity in transducing particles.
Area of Science:
- Microbiology
- Bacteriology
- Molecular Biology
Background:
- Phage 5006M is a general transducing phage for Proteus mirabilis strain PM5006.
- Investigating transduction capabilities of phage 5006M variants in other Proteus species is crucial for understanding phage-host interactions.
- Limited knowledge exists regarding the transduction efficiency and mechanisms in Proteus vulgaris.
Purpose of the Study:
- To characterize the transduction of kanamycin resistance in Proteus vulgaris strain PV127 using high-frequency transducing (HFT) variants of phage 5006M.
- To elucidate the mechanism of transduction, distinguishing between generalized and specialized transduction.
- To investigate potential defects in phage-host interactions, including phage adsorption, plaque formation, and lysogenization.
Main Methods:
- Transduction experiments using high-frequency transducing variants (5006MHFTk, 5006MHFTak) of phage 5006M on Proteus vulgaris strain PV127.
- Determination of transduction frequencies and phage adsorption rates.
- Analysis of transductant properties, including segregation of kanamycin sensitivity, response to ultraviolet irradiation, and phage liberation.
- Comparative transduction experiments on Proteus mirabilis strain PM5006.
Main Results:
- Only Proteus vulgaris strain PV127 was successfully transduced to kanamycin resistance by phage 5006M HFT variants, with low transduction frequencies (5 x 10(-8)/p.f.u. adsorbed).
- Transduction was confirmed to occur via lysogenization, as indicated by high-frequency segregation of sensitive clones and inactivation by UV irradiation.
- Two types of transductants were identified: Type I showed defective phage maturation, while Type II suggested heterogeneity among transducing particles, with neither exhibiting generalized transduction in PV127.
Conclusions:
- Phage 5006M HFT variants exhibit limited transduction capability for kanamycin resistance in Proteus vulgaris PV127, primarily through lysogenization.
- Defective phage maturation and potential heterogeneity in transducing particles contribute to the observed transduction characteristics.
- The inability to detect generalized transduction in PV127 suggests specific mechanisms or particle compositions may be required for this process.