Mold or fermentation not touching the edge of the carboy

Question

I pressed 35L of apples and the juice was pourred into a clean carboy with a muslin cloth on top, aiming to make wild cider.

After 4 days of no action, this is the carboy at 16h in day 4:

And 4 hours later, by 20h in day 4:

Is my juice infected and if so, can I still save it? Why are the white particles only localized in the middle and not going towards the edges?

Is it possible that the wild-yeast content is not high enough, and that I should get a commercial yeast? Please, any suggestions are welcome!

A closer look:

Answer 1

Looks like a standard beginning fermentation. I wouldn't worry yet. Give it time, it will likely turn out alright.

Answer 2

Your Mold or fermentation is not touching the edge of the carboy due I would imagine to the dished bottom or side form of the carboy, which is forming the interesting looking krausen. Looks like yeast is getting started.

I would always pitch a packet of yeast along side wide fermentors, but I am paranoid.

Good pictures btw.