I know no one is going to like this, but I'm writing anyways:
I think Moti killed bacteria for two reason
1: She loves her Nanka a lot, she knew arjan was tring to kill Hiten
2: DM so for reacting only two people. Santu and Moti.
he kinda seen moti killing was semi conscious when, Santu walked in after bacteria was dead. So every time either of them close to him he reacts.
we surly heading for memory loss track followed by leap.