**2.3 The pharmacological activities of bacterial-derived secondary metabolites**

Pharmaceutical agents of bacterial origin include antibiotics, immunomodulators, nematicides, antitumor agents, coccidiostatic agents, enzyme inhibitors, and insecticides. Interestingly, *Escherichia coli* is used as a host in molecular biology for synthesis of recombinant proteins [76]. Selman Abraham Waksman, the father of antibiotics, discovered actinomycin; this effort was followed by the discovery of streptomycin in 1944 [77]. Other clinically important antibiotics derived from bacteria include bacitracin [78], polymyxin B [79], gentamicin [80], amphotericin b [81], tetracycline [82], erythromycin [83], rifamycin [84], vancomycin [82], neomycin [85], streptomycin [86], and chloramphenicol [87]. Etc.
