Catabolic (degradative) plasmids: Plasmids that carry genes encoding enzymes to degrade aromatic compounds, pesticides, or unusual sugars are called what?

Introduction / Context:
Many bacteria harbor plasmids that expand their metabolic capabilities. Such plasmids confer ecological advantages by allowing the host to utilize otherwise recalcitrant substrates (e.g., xenobiotics), which is crucial in bioremediation and industrial microbiology.

Given Data / Assumptions:

• The plasmids in question encode catabolic enzymes.
• Examples include degradation of aromatics or pesticides.
• Terminology distinguishes between fertility (F), virulence, resistance, and metabolic plasmids.

Concept / Approach:

Correctly classify plasmids by the phenotypes they encode. F factors mediate DNA transfer. Virulence plasmids encode toxins or adherence systems. Metabolic (catabolic) plasmids encode pathways for unusual carbon or energy sources.

Step-by-Step Solution:

Verification / Alternative check:

Classic catabolic plasmids (e.g., TOL plasmid for toluene/xylene) exemplify this category and are used in environmental cleanup strategies.

Why Other Options Are Wrong:

F factors: primarily encode transfer functions (tra genes), not catabolism.

Virulence plasmids: promote infection, not substrate degradation.

“None of these” is wrong because a named class exists.

Common Pitfalls:

Confusing “metabolic” with “metabolism in general.” Here it specifically refers to plasmid-encoded catabolic pathways for unusual substrates.

Final Answer:

Metabolic plasmids