Penicillum
Of all the types of beneficial fungi, Penicillum is certainly the best known. Penicillum, which is a relative of the mold that is commonly found on old bread, is the active ingredient in penicillin. Penicillin revolutionized medicine when it was discovered to have strong antibacterial properties. Diseases that were formerly devastating, such as syphilis and bacterial pneumonia, could be treated quickly and effectively with penicillin. Although penicillin's efficacy has been somewhat lessened by some harmful bacteria developing resistance to it, penicillin is still in wide use as an antibiotic.