Lactobacillus casei

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Lactobacillus casei
Scientific classification
Kingdom: Bacteria Phylum: Firmicutes Class: Bacilli Order: Lactobacillales Family: Lactobacillaceae Genus: Lactobacillus Species: L. casei
Binomial name
Lactobacillus casei

Description and significance

Lactobacillus casei is a rod shaped, gram positive bacteria. It is nonsporing, nonmotile, and anaerobic. Consistent with other lactic acid bacteria, this species is acid tolerant. Lactobacillus casei dwells in environments such as the intestinal tracts of animals and fermented dairy products. It can be found naturally in both the human intestine and the mouth. They have a wide temperature range as well as a wide pH range. The mesophilic organism has a optimum temperature range around 30°C to 40°C. The optimum pH is at approximately 5.5. Scientist have found it to possess beneficial properties that support human health. It is able to improve and promote digestion. Some strains of the bacteria help control diarrhea, while other strains have an anti-inflammatory effect on the gut. Other advantageous effects include reducing lactose intolerance, alleviating constipation, and even modulation of the immune system. This natural intestinal flora creates an acidic habitat that restricts the growth of bacteria that may cause infections and inhibits any overpopulating lactic acid bacteria that resides in the gastrointestinal tract. Numerous strains have been proven to be probiotics, that is according to the World Health Organization, are "live microorganisms which when administered in adequate amounts confer a health benefit on the host." Because it is lactic acid producer, it has several applications in biotechnology and in the food industry.

Genome structure

The genome of Lactobacillus casei ATCC 334 comprise of a circular chromosome with 2,895,264 base pairs and a circular plasmid 1 with 29,061 base pairs. According to US DOE Joint Genome Institute the strain contains a total of 2,924,325 nucleotides, 2,771 number of protein genes, and 75 RNA genes.

Cell structure and metabolism

The cell structure Lactobacillus casei is typically straight, rod-shaped, and arranged in chains. The cell size tends to be around 0.7-1.1 x 2.0-4.0 micrometer. It is also a facultatively anaerobe. This means it is an organism that is able to grow under both aerobic and anaerobic environments but develops better and more rapidly in the presence of oxygen. The microbe is an organotroph and its metabolism is a homofermentative one. Unlike heterofermentative lactobacteria which can produce either alcohol or lactic acid from carbohydrates, L. casei participates in a homolactic fermentation process that can only result in one single major end product. It obtains most of its energy by converting glucose into lactic acid. Some varieties of Lactobacillus casei can produce lactic acid utilizing galactose, fructose, or even mannose. Stress, poor diet, and antibiotics can lead to a deficient growth of the bacteria.

Ecology

L.casei inhabits the oral and gastrointestinal tracts. Studies have shown that this bacteria generates health-promoting effect on the host. Their presence helps sustain a stabilized distribution of microflora in the intestine. They produces DL-lactic acid and amylase that complements the growth of Lactobacillus acidophilus

Pathology

Lactobacillus casei does not cause any diseases. Not only is it generally considered to be harmless it is well recognized as a beneficial microorganism and a nonpathogenic.

Application to Biotechnology

L. casei is an important industrial lactic acid bacteria that is involved in the production of cheese, yogurt, fermented milks, fermented Sicilian green olives, and other products. The natural end product of fermentation for this microbe is lactic acid, which inhibits the development of other organisms as well as decreasing the pH level in the food or beverage product. It is also known to be used in the development of flavor for selected cheeses.

References

[1]↑"Lactobacillus casei." Wikipedia, The Free Encyclopedia. 22 Mar 2009, 22:52 UTC. 31 Mar 2009 <http://en.wikipedia.org/w/index.php?title=Lactobacillus_casei&oldid=279033109>.

[2]↑genome.jgi-psf.org

[3]↑kegg.com

[4]↑"Lactobacillus casei." Microbewiki, <http://microbewiki.kenyon.edu/index.php/Lactobacillus_casei>

[5]↑www.probiotics-lovethatbug.com