Streptococcus thermophilus

Streptococcus thermophilus also known as Streptococcus salivarius subsp. thermophilus[1][2] is a gram-positive bacterium, and a fermentative facultative anaerobe, of the viridans group.[3] It tests negative for cytochrome, oxidase, and catalase, and positive for alpha-hemolytic activity.[3] It is non-motile and does not form endospores.[3] S. thermophilus is fimbriated.[4]

Streptococcus thermophilus
20101210 020132 StreptococcusThermophilus.jpg
Scientific classification edit
Domain: Bacteria
Phylum: Bacillota
Class: Bacilli
Order: Lactobacillales
Family: Streptococcaceae
Genus: Streptococcus
Species:
S. thermophilus
Binomial name
Streptococcus thermophilus
(ex Orla-Jensen 1919)
Schleifer et al. 1995
Synonyms

Streptococcus salivarius subsp. thermophilus (Orla-Jensen, 1919) Farrow et Collins 1984

It is also classified as a lactic acid bacterium.[5] S. thermophilus is found in fermented milk products and is generally used in the production of yogurt,[6] alongside Lactobacillus delbrueckii subsp. bulgaricus. The two species are synergistic, and S. thermophilus probably provides L. d. bulgaricus with folic acid and formic acid, which it uses for purine synthesis.[7]S. thermophilus has an optimal growth temperature range of 35–42 °C (95–108 °F), while L. d. bulgaricus has an optimal range of 43–46 °C (109–115 °F).[8]

ClassificationEdit

At least 26 strains of S. thermophilus have been identified and had their genomes sequenced.[9]

Test type Test Characteristics
Colony characters Color Yellowish
Shape Convex
Type Round
Morphological characters Shape Round
Size 0.7-0.9 μm
Physiological characters Motility -
Biological characters Gram stain +
Catalase -
Oxidase -
Cytochrome -

UsesEdit

S. thermophilus is one of the most widely used bacteria in the dairy industry. USDA statistics from 1998 showed that more than 1.02 billion kilograms of mozzarella cheese and 621 million kilograms of yogurt were produced from S. thermophilus.[10] Although its genus, Streptococcus, includes some pathogenic species, food industries consider S. thermophilus 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.[11][better source needed] Live cultures of S. 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-intolerant people find difficult to digest.[12]

Yogurt productionEdit

As early as the 1900s, S. thermophilus was used to make 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.[13]

NomenclatureEdit

"Streptococcus" derives from a Greek term meaning "twisted kernel" and refers to the way the bacterium is grouped in chains that resemble a string of beads.[14] "Thermophilus" derives from the Greek thermē, meaning "heat". It refers to an organism's ability to thrive at high temperatures.[15]

ResearchEdit

Pathogenic potentialEdit

The genus Streptococcus includes several pathogenic species, such as S. pneumoniae and S. pyogenes, but food industries consider S. thermophilus non-pathogenic. S. thermophilus is believed to have developed separately from pathogenic Streptococcus species for at least 3000 years. Research teams have sequenced the genome of two strains of S. thermophilus, CNRZ1066 and LMG13811, and stated that the bacteria are not dangerous.[16]

AdjuvantEdit

S. thermophilus strain Orla-Jensen 1919[17] is a constituent in VSL#3. This standardized formulation of live bacteria may be used in combination with conventional therapies to treat ulcerative colitis.[18][19] The use of the S. thermophilus-containing VSL#3 may reduce inflammation in mice.[20]

Reduced-fat cheeseEdit

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 S. thermophilus. These bacteria are chosen because they produce exopolysaccharide (EPS), which give reduced-fat cheese a texture and flavor like that of regular cheese.

L. lactis produces cheese with higher moisture levels compared to other reduced-fat cheeses; S. thermophilus produces cheese with a lower moisture content and a less bitter taste. It was concluded that applying both L. lactis and S. thermophilus strains would create higher-quality reduced-fat cheese with characteristics like those of regular cheese.[21]

CancerEdit

Chemotherapy 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, the intestinal tissues in those pretreated with streptococcus thermophilus TH-4 functioned more healthily and were less distressed.[22]

Antibiotic-associated diarrheaEdit

Strains of S. thermophilus have also reduced risks of antibiotic-associated diarrhea (AAD), an issue that results from taking antibiotics. Antibiotics can have the adverse effect of destroying beneficial bacteria and causing harmful bacteria to multiply, which invokes AAD. Adults who ate yogurt containing S. thermophilus while being treated with antibiotics had lower rates of AAD than the control group (12.4% vs. 23.7%).[23]

Longevity in other organismsEdit

Streptococcus thermophilus has been linked to longevity in some living organisms. In an experiment performed on the bacteriophagous nematode species Caenorhabditis elegans, consumption of S. thermophilus was shown to cause significant longevity when compared to specimens that consumed E. coli OP50, a strain used as a standard food source. Additionally, there was no significant deviation in growth rate or brood size, indicating that it wasn’t caused by caloric restriction. Instead, its life-extending effects were linked to increased expression of the gene daf-16. This effect further enhances the expression of other antioxidant genes, thereby slowing down the aging process.[24]

Health concernsEdit

Although probiotics, in general, are considered safe, there are concerns about their use in certain cases.[25][26] Some people, such as those with compromised immune systems, short bowel syndrome, central venous catheters, heart valve disease and premature infants, may be at higher risk for adverse events.[27] Rarely, the use of probiotics has caused sepsis in children with lowered immune systems or in those who are already critically ill.[28]

ReferencesEdit

  1. ^ Tannock, Gerald W., ed. (2005). Probiotics And Prebiotics: Scientific Aspects. Caister Academic Press. p. 43. ISBN 978-1-904455-01-1. Retrieved 31 March 2014.
  2. ^ "Validation of the Publication of New Names and New Combinations Previously Effectively Published Outside the IJSB: List No. 54". International Journal of Systematic Bacteriology. 45 (3): 619–620. July 1995. doi:10.1099/00207713-45-3-619.
  3. ^ a b c "Bacteria Genomes – Streptococcus Thermophilus". European Bioinformatics Institute. Archived from the original on 19 February 2013.
  4. ^ "Streptococcus_salivarius".
  5. ^ Courtin, P.; Rul, F. O. (2003). "Interactions between microorganisms in a simple ecosystem: yogurt bacteria as a study model". Le Lait. 84 (1–2): 125–134. doi:10.1051/lait:2003031.
  6. ^ Kiliç, A. O.; Pavlova, S. I.; Ma, W. G.; Tao, L. (1996). "Analysis of Lactobacillus phages and bacteriocins in American dairy products and characterization of a phage isolated from yogurt". Applied and Environmental Microbiology. 62 (6): 2111–6. Bibcode:1996ApEnM..62.2111K. doi:10.1128/AEM.62.6.2111-2116.1996. PMC 167989. PMID 8787408.
  7. ^ Sieuwerts, S.; Molenaar, D.; Van Hijum, S. A. F. T.; Beerthuyzen, M.; Stevens, M. J. A.; Janssen, P. W. M.; Ingham, C. J.; De Bok, F. A. M.; De Vos, W. M.; Van Hylckama Vlieg, J. E. T. (2010). "Mixed-Culture Transcriptome Analysis Reveals the Molecular Basis of Mixed-Culture Growth in Streptococcus thermophilus and Lactobacillus bulgaricus". Applied and Environmental Microbiology. 76 (23): 7775–7784. Bibcode:2010ApEnM..76.7775S. doi:10.1128/AEM.01122-10. PMC 2988612. PMID 20889781.
  8. ^ Lyn C. Radke-Mitchel, W. E. Sandine (1986). "Influence of Temperature on Associative Growth of Streptococcus therrnophilus and Lactobacillus bulgaricus". J. Dairy Sci. 69 (10): 2558–2568. doi:10.3168/jds.S0022-0302(86)80701-9. PMID 3805441.{{cite journal}}: CS1 maint: uses authors parameter (link)
  9. ^ "Contributing Species, Genome: Streptococcus thermophilus LMD-9, Clique ID: 480". The Integrated Microbial Genomes, The US Department of Energy Office of Science, Lawrence Berkeley National Laboratory and The Regents of the University of California. Retrieved 25 June 2016.
  10. ^ Hutkins, Robert (2002). "Streptococcus Thermophilus LMD-9". JGI Microbes.
  11. ^ Taylor, John R. and Mitchell, Deborah. The Wonder of Probiotics. New York, NY: St. Martin’s Press, 2007.
  12. ^ Leboffe, Michael (1 January 2012). Microbiology: Laboratory Theory and Application. Morton Publishing Company. p. 33. ISBN 9781617310287.
  13. ^ Delcour, J.; Ferain, T.; Hols, P. (2000). "Advances in the Genetics of Thermophilic Lactic Acid Bacteria". Food Biotechnology. 11 (5): 497–504. doi:10.1016/s0958-1669(00)00134-8. PMID 11024370.
  14. ^ "Streptococcus." Encyclopædia Britannica. Encyclopædia Britannica Online. 13 April 2011.
  15. ^ "Thermophile." Encyclopædia Britannica. Encyclopædia Britannica Online, 2011. 24 April 2011.
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  21. ^ Awad, S.; Hassan, A. N.; Muthukumarappan, K. (2005). "Application of Exopolysaccharide-Producing Cultures in Reduced-Fat Cheddar Cheese". Journal of Dairy Science. 88 (12): 4204–4213. doi:10.3168/jds.s0022-0302(05)73106-4. PMID 16291611.
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