it is the type of bacteria they use every cheese type has a different type of bacteria they use to culture the milk and make the curd the curd of the milk is actually the cheese it also has to do with the aging some cheeses have to sit up to five years before they are complete
I toured the caves in southern France where Roquefort cheese is made. They actually bake enormous loaves of rye bread and leave them in the caves along with the aging cheeses. There’s so much mold spore in the atmosphere of the caves from generations of cheese making that the loaves are naturally colonized by the particular strain of penicillin mold that is used in Roquefort. After awhile the entire loaf is blue with mold through and through. The moldy loaves are then ground to a powder. This powder is used to inoculate the fresh cheeses once they’ve been pressed into the cheese molds. It’s inserted into the cheeses using a plate studded with long spikes.
Get some cheese and food colouring and immerse the cheese into the food colouring. Hey presto, blue cheese that tastes better than actual blue cheese. :D