Why was penicillian invented?
Penicillin was actually an accidental discovery. In 1928, Dr. Alexander Fleming discovered penicillin in the mold on bread. He was amazed at its antibiotic quality.
Some molds are used in treating bacterial infections (penicillian). Others are highly toxic (stachybotrys chartarum). Any mold in height amounts are allergenic. Being your question is in food & cooking, I highly recommend NOT eating any mold, especially if you do not know what kind it is. The exception to this generally good rule is the kind intentionally included in the various blue-veined cheeses, such as gorgonzola or stilton.