In a surprising twist of nature, a particular strain of bacteria could hold the key to keeping perishables free from food poisoning. Isolated from lactic acid in raw Macedonian sheep's milk, these particular enterococci bacteria produce a handful of compounds deadly to related bacterial strains, such as listeria, which happens to be quite bad for humans and a frequent source of food poisoning. The compounds, called bacteriocins, work like a narrow spectrum antibiotic to keep listeria at bay.