Metabolic versatility – Pseudomonas pseudoflava: Pseudomonas pseudoflava (historically described) is known to grow as which type(s) of chemotroph under appropriate conditions?

Introduction / Context:
Certain non-fermentative Gram-negative rods display remarkable metabolic flexibility, allowing growth on either inorganic electron donors or organic substrates. Recognizing such facultative chemolithotrophy is useful in environmental and industrial microbiology.

Given Data / Assumptions:

• The organism named has been reported with facultative lithotrophic capabilities.
• Chemo-lithotrophs derive energy from inorganic donors; chemo-organotrophs use organic donors.
• We assume availability of suitable electron acceptors (often oxygen) in lab culture.

Concept / Approach:
Pseudomonads and related genera can exhibit broad catabolic repertoires. Historical descriptions of Pseudomonas pseudoflava include growth on organic media (chemo-organotrophy) and the capacity to oxidize selected inorganic substrates (chemo-lithotrophy) under appropriate conditions, classifying it as facultatively lithotrophic.

Step-by-Step Solution:
Define chemo-lithotrophy vs chemo-organotrophy. Map reported capabilities of the organism to both modes. Select the inclusive option indicating dual capability.

Verification / Alternative check:
Environmental isolates capable of H2 or reduced sulfur oxidation alongside heterotrophic growth exemplify this flexibility; enrichment conditions dictate which metabolism is expressed.

Why Other Options Are Wrong:
Limiting to a single mode ignores documented versatility; “none/photoautotroph” contradict established chemo-based metabolism.

Common Pitfalls:
Assuming all Pseudomonas are strictly organotrophic; several species or reclassified strains show broader chemotrophic strategies.

Final Answer:
Both (a) and (b).