What is the complete genus and species name of the bacterium most used in recombinant protein production?

• A. Staphylococcus aureus
• B. Pseudomonas aeruginosa
• C. Escherichia coli
• D. Bacillus subtilis

Answer: (C)

Choosing a host organism for recombinant protein production hinges on how fast it grows, how easily its genetics can be manipulated, and how cost-effective it is to produce large amounts of protein. Escherichia coli is the most widely used because it thrives on inexpensive media, grows quickly, and has a vast toolbox of well-characterized expression systems, plasmids, and regulatory elements that allow high-yield production. Engineered strains can reach high cell densities and direct proteins to the cytoplasm or periplasm to improve folding, which makes scaling up practical and economical. A caveat is that E. coli doesn’t perform many eukaryotic post-translational modifications like glycosylation, so some proteins require alternative hosts or special engineering. The other organisms listed have their own uses, but they aren’t the default workhorses in recombinant protein production: some are pathogens with safety concerns, while others may be better suited for secreted proteins but don’t match the versatility and efficiency of E. coli for broad applications.