Common Infection Organisms

Here are a few organisms that can infect beer, and their tell-tale characteristics that become present in beer.
Infecting Organism

Acetic Acid bacteria

Clostridium butyricum

Coliform bacteria

Hafnia protea

Lactic acid bacteria

Wild yeast

Fusarium (Barley mold)

Smells like vinegar

Smells like vomit

Cooked vegetable smell

Sour, smells like celery

Sour, buttery, or sometimes butterscotch taste, DMS (dimethyl sulfide)

Ropiness or oiliness on surface, beer remains cloudy once fermentation is complete, medicinal smell, harsh/unpleasant bitterness

This is mold that can contaminate barley in the field. Caused by excessively wet conditions will survive malting, kilning, and find its way into finished beer. Will cause uncontrolable gushing of bottles.