Streptococcus thermophilus
John Bartow

Streptococcus thermophilus ATCC# 19258, as the name implies, looks like a chain of spheres.  It is a gram-positive microbe and it is a facultative anaerobe. It does not form spores and does not move on its own. As the species name gives away, the microbe likes warmer temperatures. Its optimal growth rate occurs at the bottom of the thermophile spectrum, around 45°C.

The most interesting part about this microbe is that S. thermophilus is a lactic acid bacterium. This means that it breaks down the pyruvate into lactic acid and acetaldehyde. It is considered a homofermentative, which means that as the bacterium breaks down pyruvate most of the products formed will be lactate. Another important property of S. thermophilus is that it is a probiotic bacterium. The bacterium is healthy for the host organism that consumes it and combines this microbe with the rest of its internal flora. These two features are important for the many uses of S. thermophilus.

The first important feature mentioned was that S. thermophilus is a lactic acid bacterium. Lactic acid bacteria are known for their involvement in the fermentation of food products. S. thermophilus is one of those microbes. It is one of the most commercially important microbes and was originally isolated for the production of yogurt in 1974. Since then it has been used as a starter culture for many dairy foods including yogurt and Mozzarella cheese.  According to the USDA in 1998 around 2.24 billion pounds of mozzarella cheese and around 1.37 pounds of yogurt were produced. This microbe is the driving force behind a 5 billion dollar industry. This staggering number is one reason S. thermophilus is so interesting.

This microbe is also useful in the production and isolation of enzymes. Because S. thermophilus’ genome is shorter than most, 1.8Mb, the microbe has been the topic of several research studies to improve the organism. One such study involved the production of beta-galactosidase from the microbe. Beta-galactosidase hydrolyzes lactose and breaks it down into galactose and glucose. Beta-galactosidase is one of the most studied enzymes and is used as a marker for senescence assays as well as for tests in metabolism and enzyme kinetics.

The final feature mentioned was that S. thermophilus is a probiotic. Probiotics are commonly consumed as part of fermented foods. Sometimes specially added active live cultures are included such as in yogurt. S. thermophilus has been known to help out the internal floral of a human being. As consuming the microbe has helped to alleviate symptoms of lactose intolerance and other gastrointestinal problems. Due to this unique feature of the microbe, it has been added to several health supplements along with other probiotic bacterium. Two of these supplements include Probiotic Colon and iFlora Multi-Probiotic. I believe a third supplement is REFLORA by VÄXA. The company VÄXA never comes right out and says the microbe is found in their product. However, they spent a good deal of time describing the microbe and its benefits.

As you can see S. thermophilus is an important part of our world. Not only is it a major player in the industrial process of dairy food production, but it is also a healthy and helpful addition to the digestive system of humans.


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"Streptococcus thermophilus, Streptococcus faecium information." VAXA Offers Homeopathic Medicine, Herbal Products, Vitamins and Supplements. Web. 15 Feb. 2010. <>.

U.S Department of Energy. "Streptococcus thermophilus LMD-9 - Home." JGI Genome Portal - Home. 2009. Web. 14 Feb. 2010. <>.

"Electron microscopy of foods and microorganisms." Electron Microscopy of Foods and Microorganisms. 03 Oct. 2008. Web. 15 Feb. 2010.

*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.


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