User:Theresaly/Streptococcus thermophilus

INTRODUCTION

S. thermophilus is one of the most widely used bacterium in the $40 billion dairy industry. USDA statistics from 1998 showed that more than 2.24 billion pounds of mozzarella cheese and 1.37 billion pounds of yogurt were produced from S. thermophiles. Although its genus, Streptococcus, includes some pathogenic species, S. thermophilus is considered a safer bacterium than many other Streptococcus species. In fact, yogurt and cheese that contain live cultures of S. thermophilus are thought to be beneficial to health. Apart from being used in the food industry, S. thermophilus can prevent cancer benefit cancer patients.

TAXONOMY

Kingdom: Bacteria

Phylum Firmicutes

Class: Bacilli

Order: Lactobacillales

Family: Streptococcaceae

Genus: Streptococcus

Species: Streptococcus salivarius

GENUS STREPTOCOCCUS

CELL STRUCTURE

Streptococcus thermophilus has a thick cell wall that allows it to survive high temperatures. This is important when the bacterium is used to produce dairy products because during the process, the bacterium is elevated to temperatures of about 200 degrees Fahrenheit. Streptococcus thermophilus is safer for human consumption than other Streptococcus species because it lacks surface proteins, cell structures that can allow viruses to replicate.

GENOME STRUCTURE

NOMENCLATRE

Streptococcus derives from a Greek term meaning “twisted berry” and refers to the way the bacterium is grouped in chains that resemble a string of beads. Thermophilus derives from the Greek term thermotita meaning “heat.” It refers to an organism’s ability to thrive at high temperatures.

PROBIOTIC HEALTH BENEFITS

Live cultures of Streptococcus thermophilus make it easier for people who are lactose-intolerant to digest dairy products. The bacteria break down lactose, the sugar in milk that lactose-intolerants find difficult to digest.

Supplements Because of its probiotic nature, S. thermophilus has been added to several health supplements to aid in digestion. Examples include the Probiotic Colon and iFlora Multi-Probiotic.

S. thermophilus supplements have maintained a stable growth rate in children. Children who received S. thermophilus supplements had better growth during a 6-month period than children who did not receive the supplement.

Strains of S. thermophilus have also reduced risks of AAD (antibiotic-associated diarrhea), an issue that results from taking antibiotics. Antibiotics can have the adverse effect of destroying beneficial bacteria while causing harmful bacteria to multiply, which invokes diarrhea. Adults who ate yogurt containing S. thermophilus while being treated with antibiotics had lower rates of diarrhea than the control group (12.4% vs. 23.7%). In infants, 16% of those given S. thermophilus supplements acquired AAD compared to 31% of those who did not receive the supplement.

Yogurt Production

As long ago as the early 1900s, Streptococcus thermophilus has been used to make yogurt. Many of the yogurts sold in grocery stores today do not contain many live cultures of S. thermophilus because pasteurization destroys these beneficial organisms. Nonetheless, Streptococcus thermophilus is required by law to be present in yogurt.

Function of Bacterial Cultures

Streptococcus thermophilus is a main starter culture for yogurt. Its purpose is to turn lactose, the sugar in milk, into lactic acid. The increase in lactic acid turns milk into the gel-like structure characteristic of yogurt.

Making Yogurt at Home

Yogurt can be made at home by purchasing a starter of Streptococcus thermophilus with Lactobacillus bulgarius. First boil one quart of milk. Cool the milk until it reaches about 110 degrees Fahrenheit, and then stir in two tablespoons of bacteria. Keep the mixture at the same temperature until the milk has become a soft, gel-like structure. This should take about seven hours. For greater taste, refrigerate the yogurt before serving.

RESEARCH

Pathogenic Potential

The genus Streptococcus includes several pathogenic species, such as S.pneumoniae and S. pyogenes, but food industries consider Streptococcus thermophilus an exception. S. thermophilus is believed to have developed separately from pathogenic Streptococcus species for at least 3000 years. Research teams sequenced the genome of two strains of S. thermophilus, CNRZ1066 and LMG13811, to confirm that the bacterium is not dangerous.

When the S. thermophilus species diverged from its pathogenic relatives, it lost most of the genes acknowledged as being pathogenic. The species may have lost these genes because it adapted to a new, dairy-producing, environment in which it did not need these genes anymore.

Genome analysis has also shown that by adapting to dairy production, the species has acquired genes that its pathogenic cousins do not have. For example, the bacterium can use the energy in lactose to help itself grow.

Reduced-Fat Cheese

S. thermophilus helps make reduced-fat cheese with similar characteristics to regular, full-fat cheese. In the experiment, two different strains of bacteria are used to make reduced-fat cheddar cheese: a strain of Lactococcus lactis and a strain of Streptococcus thermophilus. These bacteria are chosen because they produce exopolysaccharide (EPS) which give reduced-fat cheese a similar texture and flavor as regular cheese. However, cheese made with Lactococcus lactis cremoris and Streptococcus thermophilus yielded various types of cheeses. Lactococcus lactis produced cheese with higher moisture levels compared to other reduced-fat cheeses. On the other hand, S. thermophilus produced low moisture cheese. It also decreased the bitterness of cheese. Applying both Lactococcus lactis and Streptococcus thermophiles strains create higher quality reduced-fat cheese with similar characteristics to regular cheese.

Cancer

Chemotheraphy often causes mucositis, severe inflammation of primarily the small intestines. Currently, there is no treatment to alleviate the symptoms of mucositis caused by chemotherapy. When rats were inflicted with mucositis by chemotherapy drugs, cells in the infected areas functioned more healthily and the tissue was less distressed. Eating yogurt stimulates enough immunity to block lung cancer in mice. Dr. Scimeca fed mice yogurt containing S. thermophiles and Lactobacillus lactis, then injected them with cancer cell. Eating yogurt reduced the expected number of cancers by one-third.