What is the goal number of CFUs on a spread plate if a serial dilution is done correctly? (A) \( 1-10 \) per plate (B) \( 20-200 \) per plate (C) \( 400-900 \) per plate (D) 1000 or more per plate

The sweet spot for colony-forming units (CFUs) on a spread plate, when you’ve nailed that serial dilution, is typically between 20 to 200 colonies per plate. This range allows for a reliable enumeration of the bacteria without overcrowding, ensuring that you can accurately count and differentiate the colonies. For some fun context, think about it this way: if you get fewer than 20, your sample might have been too diluted, which means you might miss out on the full picture. If you’re over 200, it’s like cramming too many friends into a car; things get messy, and counting those colonies becomes a real headache!