This is because there are different types of microorganisms will present in the soil and they need different nutrients to grow. The different media provide nutrients to different types of microorganisms and thus we can observe and culture the bacterial and fungal colonies needed to get better results. Besides, they can isolate both bacterial and fungal antibiotic producers. This is because soil contain mixture of mineral and organic particles. Many microbes especially bacteria that exist in soil have the ability to produce biologically active secondary metabolites such as useful antibiotics. Bacteria utilize the antibiotics they produce as protective substances by rendering the invasion of other bacterial species. Besides, soil has large and diverse population of microorganisms. Many microorganisms’ habitat are soil which provide optimum environmental factor and sufficient nutrients for microorganisms to grow.