What do spoilage bacteria do?

• A. Bacteria that cause disease
• B. Bacteria that are beneficial
• C. Bacteria that can cause rotting or spoilage
• D. Bacteria that reproduce quickly in air

Answer: (C)

Spoilage bacteria degrade food quality by metabolizing nutrients in the food and producing byproducts that cause rotting, off odors, sour flavors, and changes in texture. This directly explains why they’re associated with spoilage rather than with illness or helpful effects. They’re not primarily disease-causing pathogens, and while some microbes in food can be harmless or even beneficial in other contexts, spoilage bacteria are identified by their impact on quality and safety of the product. Reproducing quickly in air isn’t the defining trait of spoilage bacteria, since their spoilage effect depends on growth under the right conditions (temperature, moisture, pH), not simply on how fast they grow in air.