Streptomyces differs from Actinomyces because Streptomyces:

• A. is a common human pathogen
• B. is Gram-negative
• C. produces spores on aerial hyphae
• D. lacks a cell wall

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the characteristics of both Streptomyces and Actinomyces. Streptomyces is a genus of Gram-positive bacteria known for its filamentous structure and ability to produce spores, while Actinomyces is also Gram-positive but differs in certain morphological and physiological traits.
2. Step 2: Review the options given and analyze each statement in the context of these genera: whether Streptomyces is a common human pathogen, whether it is Gram-negative, whether it produces spores on aerial hyphae, and whether it lacks a cell wall.
3. Step 3: Recall that Streptomyces is not typically a human pathogen; it is mostly found in soil and is important for antibiotic production, so the statement about being a common human pathogen is incorrect.
4. Step 4: Remember that both Streptomyces and Actinomyces are Gram-positive bacteria, so the statement that Streptomyces is Gram-negative is false.
5. Step 5: Focus on the unique feature of Streptomyces producing spores on aerial hyphae, which is a key distinguishing characteristic from Actinomyces, and also confirm that both have cell walls, so the statement about lacking a cell wall is incorrect.