Streptococcus Lactis: Structure and Applications

Streptococcus Lactis: Structure and Applications The following paper describes the bacteria Lactococcus lactis previously referred to as Streptococcus lactis. Lactococcus lactis is used in the making of dairy products. The most common of these products are milk, cheese, and yogurt. Researchers are also looking at the potential of Lactococcus lactis to be used in conjunction with vaccines. I chose to write about this microbe because of the many uses and interesting facts. Lactococcus lactis has served humanity in the past; presently it remains useful in many ways and has the potential to be even a greater asset in the future. Lactococcus Lactis Introduction Lactococcus lactis (L. lactis), is a lactic acid bacteria (LAB) that is nonpathogenic and Gram-positive. The genus Lactococcus is closely related to the genus Streptococcus and is used extensively in the fermenting of milk. It is also the best-characterized lactic acid bacterium (Bolotin, Wincker, Mauger, Jaillon, Malarme, Weissenbach, Ehrlich, Sorokin, 2001). By nature, L. lactis inhabits a function connected to plant and animal surfaces and the gastrointestinal tract of the animal. On plant surfaces, it is inactive but it is believed to reproduce in the gastrointestinal tract after being swallowed (Bolotin et al., 2001). In comparison, researchers have termed what they call a domesticated species of L. lactis. This species is used in the making of dairy products such as cheese, buttermilk, and yogurt. It also serves a different function that is identified by the use of technology such as fast growth and rapid production of lactic acid in milk (Bolotin et al., 2001). Cell Morphology Streptococcus lies under the Domain Bacteria. The term strepto means chained and the term coccus means round, therefore streptococcus cells are spherical and occur in pairs or chains that can be short or long in length (Breed, Murray, Smith, 1957, p. 508). Up until 1985, L. lactis was originally classified under the genus Streptococcus (MicrobeWiki, n.d.). They are non-motile, do not produce spores and have a fermentative metabolism (Bacteria Genomes, n.d.). They also have no pigment; however, in some strains a brick-red or yellow pigment may occur under certain environments (Breed et al., 1957, p. 508). A fermentable carbohydrate or polyhydroxy alcohol is essential for suitable growth in artificial media (Breed et al., 1957, p. 508). The average coccus is small about 1 ÃŽÂ ¼m in diameter (Engelkirk Engelkirk, 2011), which may vary from rough to smooth to mucoid (Breed et al., 1957, pps. 508-509). Carbohydrate fermentation is homofermentative with dextro rotator lactic acid as t he main end result. Carbon dioxide is produced in very small amounts or not at all from sugar fermentation (Breed et al., 1957, p. 509). With respect to their nutrition, all streptococci are particular and and require a number of the B vitamins and amino acids for growth (Breed et al., 1957, p. 509). Species have their own nutritional requirements. Streptococcus is generally found wherever natural substances that contain sugars are accumulated. They occur regularly within the mouth and intestines of humans and animals, in dairy and other food products, and in plant juices that are fermenting (Breed et al., 1957, p. 509). Genome Properties The genome of L. lactis is a circular chromosome with 2,365,589 base pair, where 86% of the genome code for protein, 1.4% for RNA, and 12.6% for noncoding region. 64.2% of the genes code for known functional proteins and 20.1% of the genes for known protein with unknown function. The remaining 15.7% of the genes are unidentified proteins that may be unique to the Lactococcus (MicrobeWiki, n.d.). According to Todar, (2011), the subspecies of L. lactis are used extensively as models in lactic acid bacteria research. One subspecies, Lactococcus lactis ssp. cremoris is characterized by the laboratory strains LM0230 and MG1363, and it is best preferred for the making of hard cheeses. The other subspecies, Lactococcus lactis ssp. lactis is considered the workhorse strain and is represented by IL1403 (Todar, 2011). This subspecies is best preferred for the making of soft cheeses. Todar (2011) also suggests that beginning in 2001, these strains have been sequenced. In other words, there is a better understanding of how these bacteria are associated with their function. Finally, the ability to compare genomes has led to more knowledge of how the variety of Lactococcus strains adapt to their environments. This ability to compare has also lead to unanticipated findings. It has been suggested that this bacterium can perform aerobic respiration and can undergo horizontal gene transmission by the process of transformation (Todar, 2011). With that, it is possible that Lactococcus lactis can be used to improve minuscule things such as flavor, texture, and preservation of 10 million pounds of cheese that is produced annually (Todar, 2011). It is important to be able to examine and decipher the characteristics of bacteria in order to provide data for identification and classification (Engelkirk Engelkirk, 2011). Unique Properties As previously mentioned, Lactococcus lactis (L. lactis) is one of the most important micro-organisms in the dairy industry (Bacteria Genomes, n.d.). It is essential in the development and production of products by this industry. When L. lactis is added to milk, the bacterium uses enzymes to produce energy molecules (called ATP) from lactose. The byproduct of ATP energy production is lactic acid (Bacteria Genomes, n.d.). This lactic acid that is produced by the bacterium causes the milk to curdle and separate to produce curds, which is then used for cheese and whey (Bacteria Genomes, n.d.). The specific types of dairy that use L. lactis for its manufacturing include the cheeses Cheddar, Colby, Camembert, Roquefort, Brie, cottage cheese, cream cheese, and other dairy products such as butter, buttermilk, sour cream, and kefir (Todar, 2011). It is also accepted as a source of vegetable fermentation for pickled cucumbers and sauerkraut and for other fermented liquids such as beer and wine . L. lactis has also been considered for the development of delivering vaccines. The bacterium can be genetically engineered to produce proteins from pathogenic species on their cell surfaces (Todar, 2011). This is done by injecting an animal with a modified strain of the bacterium by way of a nasal spray. An immune response to the strain is obtained which provides an eventual immunity to the pathogen (Todar, 2011). Because L. lactis is non-pathogenic and non-colonizing it is a promising candidate for delivering biologically active proteins by mucosal routes. In a report by Chinese researchers it is described that recombinant L. lactis is applicable for the development of live mucosal vaccine against hepatitis B virus (HBV) (Zhang, Zhong, Huan, 2011). In a lab test mice were given an oral immunization and it induced both mucosal and systemic immune responses against HBV at the same magnitude. These results indicated that the lactococci-derived vaccines could be attractive candidates as alternative HBV vaccines for preventing hepatitis B (Zhang, Zhong, Huan, 2011). The increased research of L. lactis would be beneficial to people in underdeveloped countries and where sickness and other diseases is high. In conclusion, the bacterium Lactococcus lactis appears versatile. The current research suggests that, with more exploration, L. lactis can be used to improve the quality of dairy products as well as the health of individuals by way of vaccines.

War and Peace and Tolstoys View of History Essay -- Tolstoy War and P

War and Peace and Tolstoy's View of History      Ã‚  Ã‚   Count Lev Tolstoy wrote abundantly on the philosophical issues that he felt were universally important.   One of the most prolific examples of this is his view of history.   This is set out most clearly and most famously in his largest work, War and Peace.   As Tolstoy claimed himself in a public statement on the work, 'War and Peace is what the author wanted and was able to express in that form in which it was expressed.'   Not only do the themes and incidents in the novel reflect his theory of history, Tolstoy iterates this in less narrative terms in the twelve chapters of the Second Epilogue, described as, 'A general discussion on the historians' study of human life, and on the difficulty of defining the forces that move nations.   The problem of freewill and necessity.'   The view of history explored by Tolstoy has had few sympathisers and copious critics.   Tolstoy predicts this disagreement earlier in War and Peace in his description of 'the life of a bee':    A bee settling on a flower has stung a child.   And the child is afraid of bees and declares that bees exist to sting people.   A poet admires the bee sucking from the chalice of a flower, and says it exists to suck the fragrance of flowers.   A beekeeper...The higher the human intellect rises in the discovery of these purposes, the more obvious it becomes that the ultimate purpose is beyond our comprehension.   All that is accessible to man is the relation of life to the bee to other manifestations of life.   And so it is with the purpose of historical characters and nations.    This presupposition of the impossibility of a total, ultimate view of history helps to explain why Tolstoy, in his view of human actio... ...rriere, Tolstoy's Pierre Bezukhov - A Psychoanalytical Study, Melksham: Bristol Classical Press, 1993. Helen Edna Davis, Tolstoy and Nietzsche, New York: Haskell House Publishers Ltd., 1929. I Cannot be Silent - Writings on Politics, Art and Religion by Leo Tolstoy, Chippenham: The Bristol Press, 1989. E. H. Carr, What is History?, St Ives: Penguin Books, 1987. Pauline Marie Rosenau, Post-Modernism and the Social Sciences, Princeton: Princeton University Press, 1992.    Notes 1 F.F. Seeley, Tolstoy's Philosophy of History, From, Ed. Malcolm Jones, New Essays on Tolstoy, Bristol: Cambridge University Press, 1978, p. 176. 2 Ibid., pp. 178 - 183. 3 Edward Wasiolek, War and Peace: The Theoretical Chapters, From, Ed. Harold Bloom, Modern Critical Interpretations - War and Peace, New York, Chelsea House Publishers, 1988, pp. 92 - 97.   

Establish a Cooperative Socio Moral Atmosphere Essay

Reflections on Readings and Class Discussion: After reading the two articles, connecting them to the socio moral principle in a statement would be; for a child to have an established cooperative socio moral atmosphere, they need to be given the opportunity and resources in a safe environment to build and create as well as be taught positive social skills, and acquire a genuine and heart felt way to show their respect. First day of kindergarten video: The teacher did not have a classroom type D, she was very in tune with her authority over the children in the way she often told them what to do and how to do it. For example, she called the children’s attention to take roll and told the children specifically hands in your lap, eyes on me, say here when I call your name. Some children listen better while they are playing or their hands are busy which this teacher’s classroom would not take into account. Another example would be there was a teacher’s assistant who was just doing a child’s work for them, rather than helping them do it themselves. Creating Classroom Rules Video: this video was the very opposite of the first video. The teacher engaged the students and wanted their opinions and thoughts about what the classroom rules should be, but at the same time she was facilitating and not telling any child they were wrong, instead she put some ideas into new phrasing for it to make more sense. Also, the example in class about church in a heteronomous vs. autonomous relationships explains well how those who have come to see church how their parents did and it became a part of them continued to go, on the other hand those who went because they had to or did so to make their parents happy did not find a connection with what they learned and when they lived on their own decided to not go anymore. Evidenced in the CDLL Classroom Blogs: 10/24/12 The Maple room was busy as usual. Real pieces of wood and nails were new this week and the children showed quite an interest! They took turns hammering the nails into the wood and then prying them back out. The children also used materials from the Maple room to construct train tracks! In the Pine room, a continuing theme was working at a restaurant. Children and teachers sat at the table while children took orders. The orders were placed and they began to cook the meals. Some of the â€Å"daily specials† included pizza with onions, mushrooms and cucumbers, soup, hamburgers and root beer. All of the children worked together to make the restaurant run smoothly!! Evidence in CDLL Daily Documentation: 10/3/12 After our discussion, I had a table set up with measuring cups and spoons, bowls, dry and wet ingredients, leveling sticks and spoons for stirring.

Drug Abuse in Hk - 8526 Words

The Causes of Drug Abuse in Hong Kong Prepared by: Table of Contents Introduction---------------------------------------------------------------P .4 Causes of abusing substances by young people P.5-6 Causes of Abuse and Difficulties of Giving Up P.7-8 Motivations hindered behind for risking lives-P.9-10 Hong Kong Youth Caught in Wave of Ketamine Addiction P.11-12 Insights into the motivations of the drug user in Hong KongP.13-14 Conclusion----------------------------------------------------------------P.15 Works Cited---------------------------------------------------------------P.16 Appendix A-â€Å"An Examination of the Relationship between Stress and Substance Abuse in Young People in Hong Kong† Appendix B-â€Å" Cough Syrup Abuse among Young†¦show more content†¦Also, most teenagers are students. They are probably facing a lot of pressure for their academic performance. These ideas could explain that most teenage drug abusers came from inharmonic families or performed badly in school. Perhaps, they are just trying to have a moment of peace. If we want to tackle the problem of teenage drug abuse, we have to deal with the base of the problem, the inharmonic families or the high pressure from school work. Causes of Abuse and Difficulties of Giving Up The causes of teenage drug abuse are mainly the inquisitiveness, desire of high feeling, peer effect and negative emotions of the abusers according to the article. The intentions of several respondents using cough syrup A-K are being found out through interviews and thorough study of their cases. For many of those interviewees, they start taking drugs because they are interested in the feeling of taking drugs. Usually, they will get a high feeling when they take drugs. This feeling is a main reason for the teenage drug abuse. Many teenagers have an emotion of sadness from their parents, schools and friends. They want to release the bad feeling through these means. 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