First Synthetic Cell manufactured

In the beginning when he's explaining how they created the cell, he says "assembling that chromosome in yeast, transplanting it into a recipient bacterial cell".

What I don't understand is, yeast is a micro-organism in itself, as is bacteria.. he said that they transformed the bacterial cell into a new bacterial species. Doesn't that mean they basically just induced a bacterial mutation?

K_A can you help me out here? My knowledge in science isn't up to par to fully understand this.