Genus of fungi of the class Saccharomycetes. Zygosaccharomyces rouxii is responsible for spoilage of certain foods (e.g. musts, fruit juice concentrates, confectionery and honeys), and is important in the manufacture of miso, soy sauces and ogi. Z. bailii causes spoilage of mayonnaise, salad dressings, pickles, mustard, ketchups, carbonated beverages and some wines.