Distinction of two very close bacterial strains

Question

[A_heath]

Hi all,

I have a reference strain that has undergone successive passages on agar plates. I sequenced and analyzed its genome and multiple SNPs, MNPs, indels have appeared.

What is the "threshold" in terms of mutations, ANI, etc. to be able to say: "this variant is different from the reference strain" or "this variant can be considered as a new strain" ?

I would like to have your opinion on this, please.

Have a nice day,

Audrey