The antibiotic is the chemical substance produced by the microorganisms that can kill or inhibit the growth of the other microorganisms. It can be produced biotechnologically by identifying and culturing the antibiotic-producing microorganisms. Useful antibiotics are often discovered using a screening process. To conduct such a screen, isolates of many different microorganisms are cultured and then tested for production of products that inhibit the growth of test organisms. The best candidates are examined and modified by inserting isolated antibiotic coding genes with the help of vector such as plasmid. Once the process is complete, the antibiotic must be extracted and purified to a crystalline product. Thus, the correct answer is option D.