The first antibiotic was made because of properties discovered in a certain type of

 certain type of fungi

Explanation:

Antibiotic used to cure bacterial infections that is obtained from fungi of the  Penicillium genus .

Scientist Fleming discovered by accident that there was a fungus capable of killing some bacteria. In this way, he had some  culture plates (small plates of glass or plastic in which the microorganisms can grow) that  remainded forgotten and contaminated with mold, and around the growth zones of the fungus, he could see that there were no bacteria. Intrigued, he began to study that phenomenon.

I hope it can be useful. Regards!. María