Bacteria Genomes - STREPTOCOCCUS THERMOPHILUS

Streptococcus thermophilus is a Gram-positive facultative anaerobe. It is a cytochrome-, oxidase- and catalase-negative organism that is nonmotile, non-spore forming and homofermentative. Streptococcus thermophilus is an alpha-hemolytic species of the viridans group. It is also classified as a lactic acid bacteria (LAB).

Streptococcus thermophilus was once described as a bacterium "marked more by the things which it cannot do than by it's positive actions" (Sherman, 1937). Although it may be certainly be true that S. thermophilus is physiologically and biochemically less versatile than other lactic acid bacteria, the reality is that this organism is actually very versatile. Research during the past two decades has revealed that S. thermophilus has properties that make it one of the most commercially important of all lactic acid bacteria. Streptococcus thermophilus is used, along with Lactobacillus spp., as a starter culture for the manufacture of several important fermented dairy foods, including yogurt and Mozzarella cheese.

The substantial increase in production of Mozzarella cheese and yogurt have led not only to increased use of S. thermophilus cultures, but also to new demands on their performance and production requirements. Industrial strains, for example, should be insensitive to bacteriophage, have stabile fermentation characteristics, and produce products having consistent flavor and texture properties. Although research on the physiology of S. thermophilus has revealed important information on some of these properties, including sugar and protein metabolism, polysaccharide production, and flavor generation, only recently has the genetic basis for many of these traits been determined. Currently, several traits in S. thermophilus have been targeted for strain improvement programs.

S. thermophilus has an important role as a probiotic, alleviating symptoms of lactose intolerance and other gastrointestinal disorders. Immunologist lie Metchnikoff, spoke highly about the possible health benefits of the lactic acid-bacteria (LAB) Lactobacillus bulgaricus and Streptococcus thermophilus in his writings at the turn of the last century. He wrote in his book, The Prolongation of Life, that consumption of live bacteria, such as Lactobacillus bulgaricus and Streptococcus thermophilus, in the form of yogurt was beneficial for gastrointestinal health, as well as for health in general, and for longevity. Some recent research suggests that certain live microorganisms may have immunomodulatory and anticarcinogenic effects, as well as other health benefits. There is presently much active research focusing on the development of target-specific probiotics containing well-characterised bacteria that are selected for their health-enhancing characteristics. These new probiotics are entering the marketplace in the form of nutritional supplements and functional foods, such as yogurt functional food products.

The genome of S. thermophilus is 1.8 Mb, making it among the smallest genomes of all lactic acid bacteria.

References:

http://genome.jgi-psf.org/draft_microbes/strth/strth.home.html
http://www.biol.ucl.ac.be/gene/genome/
http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/pro_0034.shtml