A multi-stage experiment was conducted with two different species: a nonpathogenic strain of Buttiauxella agrestis (Ba) and a strain of Haemophilus influenzae (Hi) carrying a plasmid with a virulence gene (Hi/pVir). The cultures were treated as described for each stage (1-5, below), then inoculated into healthy mice. The mice were observed 24 hours later.
1. When Ba was inoculated ---> the mice lived
2. When Hi/pVir was inoculated ---> the mice died
3. When heat-killed Hi/pVir was inoculated ---> the mice lived
4. When Hi/pVir was mixed with Ba, the mixed cells were incubated for an hour, and then only the Ba cells were inoculated ---> the mice died
5. When Hi/pVir was first heat-killed before being mixed with live Ba, the mixed cells were incubated for an hour, and then only the Ba cells were inoculated β†’ the mice lived
a) Which was the method of DNA transfer: transformation, transduction, or conjugation? Explain your answer, including discussion of which species was the recipient and donor.