Which of the following is an advantage of using a colony counter when conducting a standard plate count in microbiology?

• A. It eliminates the need for serial dilution of samples.
• B. It prevents contamination of the agar plates during incubation.
• C. It allows for the identification of bacterial species based solely on colony appearance.
• D. It increases the accuracy and speed of counting bacterial colonies.

Answer: (D)

Verified step by step guidance

1. Understand the purpose of a standard plate count, which is to estimate the number of viable bacteria in a sample by counting colonies formed on an agar plate after incubation.
2. Recognize that a colony counter is a tool designed to assist in counting bacterial colonies more efficiently and accurately compared to manual counting by eye.
3. Evaluate each option by considering what a colony counter actually does: it does not eliminate the need for serial dilution, as dilution is necessary to obtain countable colony numbers.
4. Note that a colony counter does not prevent contamination during incubation, since contamination control depends on aseptic techniques and incubation conditions, not counting tools.
5. Understand that while colony appearance can provide clues, a colony counter does not identify bacterial species; it only aids in counting colonies, thus increasing the accuracy and speed of the counting process.