Members of this yeast genus turn up in environmental and clinical niches alike: water, soil, faecal matter, plant surfaces, wood pulp, and human skin. A few of them — T. pullulans and T. variabile among them — spoil fresh fish and shellfish, poultry, minced beef, cooked sausages, cheese, and bread. Yet T. pullulans also participates in making idli, and certain species help ripen surface-ripened cheeses such as Limburger and Gruyère. This Janus-faced genus captures a recurring food-microbiology theme: the same organism spoils one product and ripens another, depending on context and control.