What Are the Medical Uses of Saccharomyces Boulardii?

Saccharomyces cerevisiae , also known as baker's yeast or budding yeast. Saccharomyces cerevisiae is the yeast with the most extensive relationship with human beings. Not only because it is traditionally used for making food such as bread and steamed bread, and for making wine. Model organism E. coli. Saccharomyces cerevisiae is the most commonly used biological species in fermentation. Saccharomyces cerevisiae's cells are spherical or ovate, 510 m in diameter. The breeding method is budding.

Yeast belongs to fungi and is a collective name for a class of single-cell eukaryotic microorganisms. Yeast is widely distributed in nature, and it grows in an environment with high sugar content and acidity; its morphology is diverse and varies from species to species. Commonly, it is spherical, oval, oval, lemon-shaped, etc. The cell size varies greatly depending on the species. , Generally 1 ~ 5m in diameter, 5 ~ 30m or longer in length (Yu Jingzhi, 2005). Yeast has the characteristics of fast reproduction, short growth period (generally one generation every 1.5 to 2 hours), strong metabolism, and rich nutrition of the bacteria (Zhou Deqing, 2002); yeast is a facultative microorganism, and it can be used under aerobic respiration or anaerobic fermentation conditions. Can grow, anaerobic fermentation can obtain metabolites (such as alcohol, various alcohols, glycerol, enzymes, etc.), aerobic fermentation can obtain yeast cells or cell constituents (Yu Jingzhi, 2005); yeast growth and reproduction The energy required mainly comes from the catabolism of sugars. A variety of different monosaccharides and oligosaccharides, non-carbohydrates (such as polyols, petroleum crackers), and industrially produced carbon sources (such as molasses, molasses, starch, etc.) can be used. Quality raw materials such as corn and Otomo grain, sugary waste liquid, sulfite waste liquid) and so on.
More than 1,500 yeasts have been found, and more than 700 have been identified, but only a small portion are used in industry. Yeast has excellent fermentation characteristics and nutritional characteristics. In actual production, the production process of yeast fermentation can be determined according to the demand for the number of yeast cells, cell constituents, or the demand for yeast metabolites on different days. Yeast types commonly used in industry include Saccharomyces cerevisiae, Hansenula anomala (Li Ruili, 2011),

Alcoholic yeast refers to artificial cultures containing a large amount of yeasts that can convert sugars into alcohol. It is different from the concept of yeast. Yeast refers to the individual microbial yeast.

Yeast for brewing wine. Most are different varieties of Sac-charomyces cerevisiae.

The reason why yeast is used in wine production, especially artificially cultivated yeast, is to increase the wine yield. E. C. Hansen (1883) began to isolate and cultivate yeast and used it for brewing beer. The yeast below is famous at the Carlsberg Brewing Institute in Denmark. Other well-known beer yeasts include German Saaz-type yeasts, and British and Japanese yeasts. The cell morphology is the same as other cultured yeasts. It is a nearly spherical ellipsoid. Unlike wild yeast, beer yeast is a typical upper fermentation yeast commonly used in beer production.

Saccharomyces cerevisiae colonies are milky white, shiny, flat, and the edges are neat on the wort agar medium. Asexual reproduction is dominated by budding. Can ferment glucose, maltose, galactose, and sucrose, but cannot ferment lactose and melibiose.

According to the ratio of cell length to width, beer yeast can be divided into three groups:

(1) Most of the cells are round, oval or oval (cell length / width <2), which are mainly used for alcohol fermentation, brewing beverage wine and bread production.

(2) The cell shape is mainly oval and long oval, and there are round or short oval cells (cell length / width 2). This type of yeast is mainly used to make wine and fruit wine, but also used in beer, distilled spirits and yeast production.

(3) The cells are oblong (cell length / width> 2). This type of yeast is more resistant to high osmotic pressure and high salt concentration and is suitable for the production of alcohol using sugar cane molasses as a raw material.

In addition to brewing beer, alcohol and other beverages, it can also ferment bread. Bacterium has high vitamin and protein content, and can be used as edible, medicinal and feed yeast. Cytochrome C, nucleic acid, glutathione, coagulation, coenzyme A and adenosine triphosphate can be extracted from it. In the microbial determination of vitamins, beer yeast is commonly used to measure biotin, pantothenic acid, thiamine, pyridoxine, and inositol. ^[4]

More advanced applications have the following aspects:

Because Saccharomyces cerevisiae has many of the same structures as animal and plant cells that are also eukaryotes, and is easy to cultivate, yeast is used as a model organism for studying eukaryotes, and it is also one of the most known organisms. Many of the important proteins in the human body were first identified in yeast as homologs, including proteins related to the cell cycle, signaling proteins, and protein processing enzymes.

Saccharomyces cerevisiae

Saccharomyces cerevisiae is also the main raw material for making yeast extract, a common ingredient in culture media.

Yeast, as a model organism for higher eukaryotes, especially human genome research, its most direct role is reflected in the field of bioinformatics. When people discover a new human gene with unknown function, they can quickly search any yeast genome database for a known yeast gene with homologous function and obtain relevant information about its function, thereby speeding up the human Functional studies of genes. Studies have found that many genes involved in hereditary diseases have high homology with yeast genes. Studying the physiological functions of the proteins encoded by these genes and their interactions with other proteins will help deepen these genetics. Understanding of sexually transmitted diseases. In addition, many important human diseases, such as early diabetes, small bowel cancer, and heart disease, are polygenic hereditary diseases. Revealing all relevant genes involved in these diseases is a difficult and long process. Yeast genes and human polygenic heredity The similarity between disease-related genes will provide important help for humans to improve the level of diagnosis and treatment.

The best example of yeast as a model organism is reflected in the research of genes related to human genetic diseases obtained by linkage analysis, location cloning, and sequencing verification. The latter's nucleotide sequence is homologous to the yeast gene for its function Research has provided excellent clues. For example, human hereditary non-polyposis small bowel cancer-related genes and yeast's MLH1, MSH2 genes, ataxia-related telangiectasia-related genes and yeast's TEL1 gene, Bloom's syndrome-related genes and yeast's SGS1 gene are all Has high homology. Hereditary nonpolyposis small intestine oncogene exhibits a cell phenotype with unstable short nucleotide repeats in tumor cells, and before the human gene was cloned, researchers isolated genes with the same phenotype in yeast Mutations (msh2 and mlh1 mutations). Inspired by this result, it was speculated that small intestine oncogenes are homologous genes of MSH2 and MLH1, and their homology in nucleotide sequences further confirmed this speculation. Bloom's syndrome is a hereditary disease with precocious puberty. Cells of patients show a shortened life cycle phenotype when cultured in vitro, and its related genes share the same genes as the SGS1 gene encoding snail enzymes in yeast. High homology. Similar to cultured cells from individuals with Bloom's syndrome, yeast cells with a mutation in the SGS1 gene showed a significantly shortened life cycle. Francoise et al. Studied more than 170 human genes obtained through functional cloning and found that 42% of them have obvious homology with yeast genes. Most of these human gene coding products are related to signal transduction pathways, membrane transport or DNA synthesis. It is related to repair, and those human genes that have no obvious homology with yeast genes mainly encode some membrane receptors, blood or immune system components, or some important enzymes and proteins in human specific metabolic pathways.

SEM photograph of Saccharomyces cerevisiae

As more genetic information of higher eukaryotes is obtained, people will find that more yeast genes have higher homology with higher eukaryotic genes, so the role of the yeast genome in the field of bioinformatics will become more important. At the same time, research on the yeast genome will also be promoted. Compared with yeast, higher eukaryotes have a richer phenotype, which makes up for the lack of obvious phenotypic changes in certain gene mutations in yeast. The examples that will be mentioned below illustrate the mutually reinforcing relationship between yeast and human genome research. Human pigmented dry skin disease is an autosomal recessive skin disease that can easily develop into skin cancer. As early as 1970, Cleaver et al. Reported that both dry skin disease and UV-sensitive yeast mutants are related to the lack of nucleotide excision repair (NER). In 1985, the first NER pathway related gene was sequenced and confirmed to be the RAD3 gene of yeast. In 1987, Sung first reported that yeast Rad3p could repair a defect in DNA helicase activity in eukaryotic cells. In 1990, xPD, a gene related to xeroderma pigmentosum, was cloned and found to have very high homology with the RAD3 gene of the yeast NER pathway. It was later discovered that all human NER genes can find corresponding homologous genes in yeast. A major breakthrough came from 1993, when human xPBp and xPDp were found to be the basic components of the TFIIH complex of RNA polymerase II in the transcription mechanism. So people speculated that xPBp and xPDp's homologous genes in yeast (RAD3 and RAD25) should also have similar functions. Based on this clue, they quickly obtained satisfactory results and confirmed the original guess.

The role of yeast as a model organism is not only in bioinformatics, but yeast also provides a detectable experimental system for higher eukaryotes. For example, the function of a heterologous gene and a yeast gene can be utilized to confirm the function of the gene. According to incomplete statistics by Bassett, by July 15, 1996, at least 71 pairs of human and yeast complementary genes have been discovered. These yeast genes can be divided into six types: 20 genes and biological metabolism including the synthesis of biological macromolecules , Respiratory chain energy metabolism, and drug metabolism; 16 genes are related to gene expression regulation, including transcription, post-transcription processing, translation, post-translation processing, and protein transport; 1 gene encodes a membrane transport protein; 7 genes It is related to DNA synthesis and repair; 7 genes are related to signal transduction; 17 genes are related to cell cycle. It is found that more and more human genes can compensate for the mutant genes of yeast, so the number of human and yeast complementary genes has far exceeded the previous statistics.

Functional complementation experiments in yeast are undoubtedly a shortcut to study the function of human genes. If a human gene with unknown function can compensate for a mutant gene with a known function in yeast, it indicates that the two have similar functions. For some human genes with known functions, it is also important to perform functional complementation experiments. For example, the three human genes GALK2 (galactose kinase), GALT (UDP-galactosyltransferase), and GALE (UDP-galactose isomerase) related to galactosemia can compensate the corresponding GAL1, GAL7, GAL10 gene mutation. Before the complementary experiments were performed, the lactose metabolism pathways of both humans and yeasts were very clear, and the detection methods for the activities of several enzymes were also very sound, and their pure products were obtained, which could be subjected to a series of biochemical analysis. With the successful isolation and isolation of three human galactosemia-related genes, functional complementation experiments became possible, thereby further confirming the conservation of human galactosemia-related genes and yeast genes at the genetic level. People have also promoted this result, using the yeast system for galactosemia detection and gene therapy, such as distinguishing between true mutants and genetic polymorphisms, simulating the combined phenotype of multiple mutants in yeast, or screening Inhibit mutations within or between genes. These methods are also applicable to the study of other genetic diseases.

Utilizing the functions of heterologous genes and yeast genes, yeast can also be used as a screening tool for new genes in other organisms. By using specific yeast gene mutant strains to screen human cDNA expression libraries, complementary clones were obtained. For example, Tagendreich et al. Used yeast cell division mutants (cdcmutants) to isolate multiple homologous genes that play a role in human cell mitosis. Using this method, people also cloned several new genes isolated from crops, livestock, and poultry.

In order to give full play to the role of yeast as a model organism, in addition to developing yeast bioinformatics and sound research methods for functional complementation of heterologous genes in yeast, it is also a feasible approach to establish the smallest yeast genome. Yeast minimal genome refers to the reduction of all apparently abundant genes to the minimum number that allows yeast to grow in synthetic media under experimental conditions. Genetic complementation of human cDNA clones with defective functionally known genes in yeast can determine the function of new human genes, but this complementarity experiment will be affected by other redundant genes in the yeast genome. If the genes retained in the minimal yeast genome can be completely replaced by human or viral DNA sequences, the replacement phenotype will depend entirely on the foreign gene, which will become an analysis for screening anticancer and antiviral drugs. system.

Brewing yeast production

yeast

Fermentation curve of brewing yeast

Dry wine stuffed yeast

Yeast