Streptococcus thermophilus

Streptococcus thermophilus under a microscope

Streptococcus thermophilus is a Gram-positive bacterium that is widely used in the production of dairy products. It is a member of the Streptococcus genus and is known for its role in the fermentation process of yogurt and cheese.

Characteristics

Streptococcus thermophilus is a thermophilic lactic acid bacterium, meaning it thrives at higher temperatures, typically between 45°C and 50°C. It is a facultative anaerobe, capable of surviving in both oxygen-rich and oxygen-poor environments. This bacterium is non-motile and forms chains of cocci, which are spherical cells.

Role in Fermentation

In the production of yogurt, Streptococcus thermophilus is often used in combination with Lactobacillus delbrueckii subsp. bulgaricus. These bacteria work synergistically to ferment lactose, the sugar present in milk, into lactic acid. The production of lactic acid lowers the pH of the milk, causing it to coagulate and form the characteristic texture and tangy flavor of yogurt.

In cheese production, Streptococcus thermophilus is used as a starter culture. It helps in the acidification of milk, which is a crucial step in the cheese-making process. The bacterium's ability to rapidly produce lactic acid makes it an essential component in the production of various types of cheese, including Mozzarella and Swiss cheese.

Health Benefits

Streptococcus thermophilus is considered a probiotic, which means it can confer health benefits when consumed in adequate amounts. It is believed to improve lactose digestion in individuals with lactose intolerance by breaking down lactose into simpler sugars. Additionally, it may contribute to gut health by maintaining a balanced microbiota in the digestive system.

Genomic Features

The genome of Streptococcus thermophilus has been sequenced, revealing insights into its metabolic pathways and adaptation to dairy environments. The bacterium possesses genes that enable it to efficiently utilize lactose and other sugars, as well as genes that confer resistance to phages, which are viruses that infect bacteria.

Industrial Applications

Beyond its use in dairy fermentation, Streptococcus thermophilus is also employed in the production of probiotic supplements and functional foods. Its ability to survive the acidic conditions of the stomach makes it a suitable candidate for delivering beneficial bacteria to the intestines.

Related Pages

• Lactobacillus delbrueckii subsp. bulgaricus
• Yogurt
• Cheese
• Probiotic
• Lactic acid bacteria