In a typical bacterial growth curve figure with lines labeled A, B, C, and D, which line most likely represents the growth of an obligate aerobe incubated in an anaerobic environment?

• A. Line C, which shows slow but steady growth
• B. Line A, which shows no increase in cell number over time
• C. Line D, which shows initial growth followed by a rapid decline
• D. Line B, which shows exponential growth throughout incubation

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the characteristics of an obligate aerobe. These bacteria require oxygen for growth because they rely on aerobic respiration to generate energy.
2. Step 2: Consider the environmental condition given: an anaerobic environment, meaning no oxygen is present.
3. Step 3: Predict the growth behavior of an obligate aerobe in the absence of oxygen. Since oxygen is essential for their metabolism, they will not be able to grow or multiply.
4. Step 4: Analyze the growth curve lines: a line showing no increase in cell number over time indicates no growth, which matches the expected behavior of an obligate aerobe in anaerobic conditions.
5. Step 5: Conclude that the line representing no increase in cell number (Line A) most likely corresponds to the obligate aerobe incubated anaerobically.