Lactococcus lactis
| Pseudomonas putida | ||||||||||||||
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| Pseudomonas putida |
Description and significance
"Lactococcus Lactis" is a non pathogenic,Gram-positive bacteria known as one of the most important microbes in dairy food production. Lactococci lactis, which is closely related to the strptococcus genus, has two subspecies, Lactococcus lactis subsp. and Lactococcus cremoris subsp. They are used to make soft and hard cheese respectively. L.Lactis group in pairs or short chains with a length of about 1.2µm by 1.5µm. Lactococci are immotile, nonsporelating, and are usually spherical or ovoid cells. L. Lactis is the starter culture for the production of fermented dairy products such as milk, cheese, yogurt, etc. Lactococcus is a considered a opurtunistic pathogen because of its ability to produce lactic acid. Lactic acid produced by the the microbe curdles the milk which seperates into curds inturn are used to produce cheese and whey.In nature, L. lactis is found to be inactive on plant surfaces and on to multiply in the gastrointestinal tract after being swallowed by an animal.
Genome structure
Cell structure and metabolism
"Lactococcus lactis" functions through both aerobic and anaerobic metabolic pathways. The primitive source of energy is produced anaerobicly, which results in the accumulation of lactic acid. the deprivation of oxygen leads the glycolysis process to breakdown carbohydratesinto pryvate which then convert into lactic acid. this process is only possible through the production of the lactate dehydrogenase enzyme and NAD. Lactate is transported to the median which causes the efflux of protons resulting in the appropriate membrane potential for energy production. The lactic acid produced is used for food production.Aerobic respiration is also used as a supplemental metabolic process. When oxygen and a heme source is present new traits are observed such as increased growth index, resistance to oxidative and acid stress, and long-termed endurance at low temperatures. Along with heme source, the presence of membrane bound NADH dehydrogenase oxidizes NADH and increases the cell growth and production of proteins and vitamins.
Ecology
Pathology
Lactococcus lactis is a non-pathogenic bacteria.
Application to Biotechnology
Extensive research has been attributed to the sequencing of Lactococcus lactis' genome due to its major role in the production of dairy products and preservation. Manufactures use the discovered properties of L.lactis to increase food preservation, distinguish flavor and aroma. L.lactis contains a bacteriocin, a natural antimocrobial agent that fights against a wide range of Gram-positive bacteria, such as food-bourne pathogens. Uses of nisin to control spoilage lactic acid bacteria have been identified in beer, wine, alcohol production, and high acid foods such as salad dressings. Production of highly purified nisin preparations has led to interest in the use of nisin for human ulcer therapy and mastitis control in cattle.
A recently discovered application of Lactococcus lactis is in the development of vaccine delivery systems. L.lactis can be genetically engineered to generate proteins from pathogenic species on their cell surfaces. Intra nasal injection of a mammal with the modified strain will elicit an immune response to the cloned protein and provide immunity to the pathogen. This approach theoretically can be applied to any pathogen that enters a human or mammal through a mucoasal surface, however, it is most commonly used to provide immunity to Streptococcus pyogenes, the pathogenic agent of strep throat.