Final answer:
A large percentage of antibiotics and semisynthetic drugs are produced by members of the genus Streptomyces, which are used for human treatment due to their microbial toxicity but human non-toxicity.
Step-by-step explanation:
A large percentage of antibiotics and semisynthetic drugs are produced by members of the genus Streptomyces. These microbes are cultivated under suitable fermentation conditions to produce the desired antibiotics, and sometimes mutant microbes are utilized for industrial production to increase yield and efficiency. For example, Streptomyces nodosus is known for producing Amphotericin-B, and Streptomyces venezuelae produces Chloramphenicol. Streptomyces species are prolific producers of many other antibiotics like Erythromycin, Streptomycin, and Tetracycline, which all play vital roles in human treatment by being toxic to the invading microbes but non-toxic to humans.
Streptomyces is a genus of bacteria that are filamentous and gram-positive. Many significant antibiotics, such as streptomycin and tetracycline, are produced by Streptomyces species under suitable fermentation conditions.