Lactobacillus casei

Description and significance
Lactobacillus casei is a rod shaped, gram positive bacteria. It is nonsporing, nonmotile, and anaerobic. 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. Scientist have found it to be beneficial in many ways. 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 and alleviating constipation. 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." They have a wide temperature range as well as a wide pH range. The optimum temperature range from 30°C to 40°C and the optimum pH is at 5.5. Lactobacillus casei is also a lactic acid producer, which means it has several applications in biotechnology and in the food industry.

Cell structure and metabolism
The cell structure Lactobacillus casei is typically straight and rod-shaped. 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. L. casei is a 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 end product. This microbe obtains most of its energy by converting glucose into lactic acid. Some varieties of Lactobacillus casei can produce lactic acid utilizing galactose, fructose, or mannose.

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
Lactobacillus casei is usually the predominant species of non-starter lactic acid bacteria that is involved in the ripening of Cheddar cheese and in naturally fermented Sicilian green olives.