This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, Subject name: Microbiology
[{'content': 'The bacterium that is most commonly used in genetic engineering is \nSelect and explain. \nA. Escherichia, B. Klebsiella, C. Proteus, D. Serratia', 'role': 'user'}, {'content': "Answer: A \nExplanation: GENETIC ENGINEERINGEngineering is the application of science to social needs. Recombinant plasmids may be introduced into a bacterial host, frequently E coli, by forced transformation. Alternatively, electroporation is a procedure that introduces DNA into bacteria using an electrical gradient.Ref: Jawetz, Melnick, & Adelberg's Medical Microbiology; Twenty-Seventh Edition; Chapter 7; Microbial Genetics", 'role': 'assistant'}]