Egg spoilage — ‘‘Green rot’’: This defect in eggs is chiefly associated with which bacterium?

Introduction / Context:
Different bacterial species impart signature colors and odors in spoiled eggs. ‘‘Green rot’’ is one such diagnostic discoloration helping trace the causative agent.

Given Data / Assumptions:

• Defect: greenish discoloration of egg contents, often with fruity or putrefactive notes.
• Storage conditions: chilled but long-held, or temperature abused.
• Suspects include Pseudomonas and general spore-formers/skin flora.

Concept / Approach:
Pseudomonas fluorescens and related psychrotrophs produce pigments and enzymes that lead to a characteristic green hue in albumen. Their ability to grow at refrigeration temperatures makes them prominent in egg and dairy spoilage.

Step-by-Step Solution:
Associate green color with Pseudomonas pigment/enzymatic activity. Exclude generalists that do not typically cause green rot. Choose P. fluorescens.

Verification / Alternative check:
Spoilage compendia attribute green rot predominantly to Pseudomonads, notably P. fluorescens.

Why Other Options Are Wrong:

• Micrococcus/Bacillus: assorted spoilage but not the hallmark green rot.
• Molds/yeasts: different visual and sensory profile.
• All of the above: overly broad; not specific to green rot.

Common Pitfalls:
Confusing black rot (Proteus) with green rot (Pseudomonas), leading to wrong hygiene interventions.

Final Answer:
Pseudomonas fluorescens