The microbes that produce most antibiotics are primarily bacteria, specifically from the genera Streptomyces, Bacillus, and Penicillium.

Here's a breakdown:

* Streptomyces: This genus is the most prolific producer of antibiotics, responsible for over two-thirds of clinically used antibiotics. Some examples include streptomycin, tetracycline, erythromycin, and vancomycin.

* Bacillus: This genus also produces a variety of antibiotics, including bacitracin, polymyxin, and gramicidin.

* Penicillium: Famous for producing penicillin, this fungus also contributes to other antibiotics like griseofulvin.

While these are the most prominent sources, other bacteria and fungi also produce antibiotics, and research continues to identify new sources.