Bacteria used to make cheese
Cheeses get their variety of tastes, smells and textures, in part, from different kinds of bacteria. Bacteria helps develop the acidity necessary to turn milk into cheese and also assists in the ripening of cheese.
Fresh cheese requires little more than the bacteria naturally present in milk, but ripened or aged cheeses usually need additional bacteria. Two main types of bacteria are used to make cheese: thermophilic (heat-loving) and mesophilic (preferring moderate temperatures). Whichever type of bacteria is used, cheese cannot be made without it.
Naturally present in milk, lactic acid bacteria contributes to the acidity and ripening of cheese. Cheeses such as ricotta, queso blanco and cottage cheese can be made without additional cultures.
Starter Cultures: Yogurt
Lactococcus thermophilus and Lactobacillus bulgaricus are thermophilic bacteria commonly found in yoghurt. These bacteria can also be mixed with other bacteria to form the starter culture to produce other cheeses.
Cheddar and cheddar-type cheeses are made with Lactococcus lactis and Lactococcus cremoris, both of which are lactic acid bacteria. Cheddar's unique flavour comes from the process by which it is made.
Feta, Camembert and Mozzarella
Lactococcus lactis and Lactococcuscremoris are mesophilic bacteria are used in conjunction with Lactococcus thermophilus and Lactobacillus bulgaricus to make feta, Camembert and mozzarella.
Hard and Semi-Hard Yellow Cheeses
L. lactis, Lactococcus cremoris, Lactococcus diacetylactis and Leuconostoc cremoris are used to make most typical hard and semi-hard yellow cheeses. Emmanthaler is an exception; it needs a thermophilic starter culture, such as Lactobacillus helveticus and Lactococcus thermophilus.
Blue cheeses, such as Gorgonzola, get their characteristic blue-green colour from mould, not bacteria. Some blue cheeses are inoculated with specific moulds; others have holes poked in them before they are aged, so naturally occurring moulds can grow in the cheese.