Contributions of pneumococcus to bacterial genetics
Of course Avery et al. 1944 first focused attention on DNA. So it had everything to do with molecular genetics.
But pneumococcus was too difficult to work with.* That motivated search for other systems - esp. Haemophilius and Bacillus,
eventually E. coli.
But don't overlook:
Hotchkiss and Marmur ca. 1951 linkage in transformation (followed by Nester-Ganesan-JL 1963 PNAS 49: 61-68 in B. subtilis)
that associates linkage with covalent coupling on DNA molecules.
* and so there has been no growing school of pn. research as there has for other systems used in bacterial genetics.
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There is no logic of connection between models of bacterial conjugation and whether there is an organized nucleus.
With a single "chromosome" the only considerations would be a nuclear membrane, and this disappears during mitosis/meiosis
in any event.
(Certainly my thinking!)
My own writings were quite skeptical of the miotic figures claimed by Bisset or Delamator. But I could not disprove mitosis
with light microscopy -- esp. if one postulated a single long floppy chromosome barely readable.