Antibiotics: Neomycin B is produced by which Streptomyces species?

Introduction / Context:
Neomycin is an aminoglycoside antibiotic complex (notably neomycin B and C) used topically and in some oral applications. Knowing the producing organism guides both historical understanding and strain selection for industrial processes.

Given Data / Assumptions:

• Question targets the species associated with neomycin B.
• We differentiate among several Streptomyces producing different aminoglycosides.

Concept / Approach:
The classic producer of neomycin B (and C) is Streptomyces fradiae. Other species listed are known for different products: for example, S. griseus famously produces streptomycin. Correct identification relies on matching antibiotic families with their canonical producing strains.

Step-by-Step Solution:

Verification / Alternative check:
Pharmacognosy and fermentation process sources document neomycin biosynthesis in S. fradiae, including gene clusters for aminoglycoside assembly.

Why Other Options Are Wrong:

• Streptomyces griseus: producer of streptomycin, not neomycin B.
• Streptomyces spheroides / Streptomyces niveus: associated with other metabolites; not the classic neomycin B source.

Common Pitfalls:
Confusing aminoglycoside producers because multiple Streptomyces make related compounds; pay attention to the specific molecule.

Final Answer:
Streptomyces fradiae