What spoilage microbes benefit from oxygen in wine?

• A. Lactobacillus and Pediococcus
• B. Saccharomyces cerevisiae and Saccharomyces bayanus
• C. Aspergillus niger
• D. Acetobacter, Brettanomyces

Answer: (D)

Oxygen fuels certain spoilage microbes, so those that actually rely on or gain from air exposure in wine will thrive when oxygen is present. Acetobacter is a strict aerobe that oxidizes ethanol to acetic acid, giving vinegar-like aromas, and Brettanomyces is a spoilage yeast whose growth and production of off-aromas are enhanced in oxygen-rich conditions. The other options don’t hinge on oxygen in the same way: lactic acid bacteria can grow with or without oxygen, Saccharomyces yeasts are primarily fermentative and not considered oxygen-loving spoilage microbes, and Aspergillus niger is a mold more associated with grapes or must surfaces than with typical wine spoilage in the bottle.