Is this black mould?

Hello there,

My husband and I just moved into a house we are renting and decided to buy some stick on tiles for the bathroom to update it a little bit since it's an older house. I took off the old stick on tiles and found that there was a bloated piece of subfloor next to the tub thats almost like a cardboard-like texture. It seemed to be mouldy and broke apart easily so I ripped it all out. Underneath is a piece of wood that is inot pretty decent shape but on one side it looks mouldy. I'm wondering if I should treat it with bleach and the get a new thing piece of sub floor to nail down and then put the tiles on top OR if this is black mould and I should take the board out.

I wasn't aware while taking the subfloor out that black mould was extremely u healthy to breathe in so I wasn't wearing a mask
(I know that was incredibly stupid of me)

First pic is the subfloor before ripped out
Second is out bathroom floor with wood along tub without subfloor
Third is the bad corner without subfloor

Thanks for the help
Jamie

 

My landlord said to get mould killing primer and paint over it and then let dry before installing new subfloor. If it is black mould and we just do that, will it be harmful still from beneath the floor board? Cos I personally don't care if it continues to eat at his property since I made him aware of it and it's his choice to deal with it the cheaper way. I just wanna make sure it's not gonna harm us, you know?

 

Thank you very much. I will fight to have it tested before we patch up the floor.

And thank you to everyone else as well who replied to this thread.