Final answer:
The isolates with a 97% average nucleotide identity for shared orthologous genes would most likely be classified as individual strains of the same species, not as individual species or different families. Option A is the correct answer.
Step-by-step explanation:
The question asks whether 12 new isolates from the human skin with an average nucleotide identity of 97% for shared orthologous genes would most likely be classified as individual strains of the same species, as individual species of the same genus, split into different families, or classified as the same species if they can mate via conjugation.
In microbial taxonomy, an average nucleotide identity (ANI) of 95-96% or higher typically suggests that the isolates belong to the same species. Since the 12 isolates have a 97% ANI, they would most likely be classified as individual strains of the same species. This high percentage indicates a very close genetic relationship amongst the isolates, suggesting they are variants of a single species rather than distinct species or genera.
Furthermore, conjugation is not a universally applicable criterion for species determination, especially in bacteria where horizontal gene transfer can occur across species boundaries. Hence, the ability to mate via conjugation is not a definitive factor for species classification in this context.
Therefore, the correct option for classifying the 12 isolates with a 97% average nucleotide identity in shared orthologous genes would be A) classified as individual strains of the same species.