1.1 Biological Introduction of Saccharomyces Cerevisiae
Saccharomyces cerevisiae, also known as bread yeast or budding yeast. There are two life forms of saccharomyces cerevisiae cells: haploid and diploid. The optimal growth temperature for brewing is 28℃, but it can also grow at appropriate high temperatures. As one kind of unicellular eukaryotic organism, saccharomyces cerevisiae has all the basic features of eucell life and many advantages as an experimental microorganism, such as clear background, fast growth, easy operation,etc. Much regularity cognition in modern genetics, cell biology, and biochemistry were discovered through experiments using yeast cells. Saccharomyces cerevisiae is considered to be the most promising microorganism for large-scale production.
1.2 Morphological Characteristics ofSaccharomyces Cerevisiae
Saccharomyces cerevisiae is a unicellular organism with an oval or spherical shape. It has a cell wall, cell membrane, nucleus (extremely small and often difficult to see), vacuole, mitochondria, and various storage substances such as oil droplets and glycogen. The yeast colonies grown on malt extract agar medium are white, shiny, flat, and have even edges. The cell width is 2.5-10μm, the length is 4.5-21μm, and the length-to-width ratio is 1-2. They are mostly round, oval, or ovate.
1.3 Functional Substances of Saccharomyces Cerevisiae
Saccharomyces cerevisiae contains rich protein, vitamins, minerals, polysaccharides, and many biologically active substances, with complete sets of enzymes and 2.5%-10% ribose nucleic acid (RNA). The cell wall of saccharomyces cerevisiae contains rich beta-1,3-glucans and mannan oligosaccharide (MOS), with its content reaching about 95% of the dry weight of the cell wall; the protoplasm of yeast cell contains abundant small peptides; Saccharomyces cerevisiae contains superoxide dismutase (SOD).
2.1 Preparation Work
(1) Strain: saccharomyces cerevisiae.
(2) Reagents: Fehling reagent, 0.2% standard glucose solution,liquifying enzyme, saccharifying enzyme, sodium hydroxide, methyl blue solution, concentrated sulfuric acid, and crude compound enzymes.
(3) Instruments and Equipment: Desktop centrifuge, saccharimeter, alcohol meter, thermostatic water bath, electronic balance, sterilizer, incubator, magnetic stirrer, oscillator,etc.
(4) Medium: Solid slope complete culture medium (YEPD), Distillate culture-medium, fermentation medium.
2.2 Fermentation Process
The strains to be tested were cultured in fresh oblique culture medium and inoculated on seed culture medium after being verified for stability through oblique culture. When the number of cells reached 1x109cell/ml, that is, during the logarithmic growth phase, the inoculated amount of 15% of the volume of fermentation medium is inoculated into the fermentation medium.Specific operations are as follows:
(1) The strains are activated twice at 30℃ on the inclined surface of YEPD and inoculated in 20x20 large test tubes containing 8ml of 14oBx seed saccharification solution and cultured at 30℃ for 16-20 hours;
(2) The bacterial solution is put into 250ml triangular bottle containing 100ml 14oBx seed saccharification solution and cultured at 30℃ and 200rmp for 10-12 hours;
(3) A 500ml triangular bottle is used for fermentation with 255g fermentation medium. When the number of cells reached 1X109cell/ml, that is, during the logarithmic growth stage, 45g of the secondary seed solution is inoculated into the fermentation medium, fitted with fermentation tether, and incubated at 30℃.
(4) After 12 hours, seal with concentrated sulfuric acid, adjust the temperature of the fermentation incubator to 34℃, and let fermentation stand for 60 hours;
(5) Weigh once every 12 hours during the period, record the weight reduction, and find the weight loss of carbon dioxide;
(6) After fermentation, some data can be measured, such as alcohol, apparent degree of attenuation, reducing sugar, acidity and other parameter values, it will be used for later data processing and analysis.
As a representative of single-cell eukaryotes, Saccharomyces cerevisiae has mature fermentation process and high biosafety, and is mainly used in the brewing production of fuel ethanol, liquor, wine, beer, etc. Alive bacteria, inactive components and cell components of saccharomyces cerevisiae have also been widely used in animal husbandry and feed industry.
3.1 Application of Saccharomyces Cerevisiae in Brewing Industry
Saccharomycetes will absorb glucose, fructose, mannose and other monosaccharides into the cell, in the absence of oxygen, through the action of endogenous enzymes, the monosaccharides are decomposed into carbon dioxide and ethanol, this effect is fermentation.
3.2 Application of Saccharomyces Cerevisiae in Animal Husbandry
Alive bacteria can be used as probiotics or fermentants. It can promote the reproduction of beneficial bacteria in animal gastrointestinal tract and improve the microecological balance of animal gastrointestinal tract. It can effectively absorb intestinal pathogens. Saccharomyces bradyensis has natural heat resistance and good acid resistance. Saccharomyces Brady can secrete polyamines (putrescine, spermine and spermidine) to promote the maturation of the animal intestine and enhance the absorption capacity of nutrients by intestinal cells. Saccharomyces cerevisiae can be used as the fermentation agent, or combined with other probiotics, which is used for the fermentation treatment of feeding raw materials to enhance the value of raw materials.
3.3 Application of Saccharomyces Cerevisiae in Feed Industry
The inactive form and cell components of saccharomyces cerevisiae can be used as organic trace elements of yeast, functional protein raw materials, immune enhancement agents, mycotoxin adsorbent, antibacterial and growth promoting agents. Saccharomyces cerevisiae is rich in protein, nucleic acid, vitamin, polysaccharide and other nutrients, which plays an obvious role in inducing food and promoting growth, and has the potential to replace plasma protein powder and fish meal.
3.4 Application of Saccharomyces Cerevisiae in Biological Scientific Research
(1) The application of saccharomyces cerevisiae as the model organism in the function identification of exogenous genes
Saccharomyces cerevisiae has a small genome, short life cycle, rapid reproduction, plus easier experimental operation, with simple plate photocopying ability, which is very suitable for short genetic cycle, rapid reproduction, plus easier experimental operation, with simple plate photocopying ability, it is very suitable for genetic analysis and research. At the same time, saccharomyces cerevisiae has stable haploid and diploid cells. Under experimental conditions, the diploid and haploid states of saccharomyces cerevisiae can be converted.
(2) Application of saccharomyces cerevisiae as a model organism in the study of human gene function
Saccharomyces cerevisiae, as a unicellular eukaryote, has similar structural characteristics to animal and plant cells, including cell nucleus, endoplasmic reticulum, Golgi apparatus, mitochondria, peroxisome, cytoskeleton, etc. Moreover, its cell growth and development process is also very similar to that of animal and plant cells, and many genes are highly conserved in yeast and animal and plant cells. Moreover, yeast cells are easily manipulated in biochemistry and molecular biology, so yeast is a commonly used model organism in the study of gene function.
3.5 Application of Saccharomyces Cerevisiae in Medicine
Yeast is rich in vitamin B, protein and a variety of enzymes, so the bacteria system is made into yeast tablets, it is used to treat indigestion; Raw materials for the production of nucleic acid derivatives, coenzyme A. cytochrome C, glutathione and various amino acids can also be extracted from yeast. It can also be used to produce recombinant hepatitis B vaccine (saccharomyces cerevisiae).
3.6 Other Applications of Saccharomyces Cerevisiae
Saccharomyces cerevisiae has better food safety than other microorganisms. It is blessed with low pH tolerance, which is conducive to efficient accumulation of organic acids and lower downstream extraction and purification costs; It has high glucose tolerance and lays the foundation for achieving high density fermentation. Saccharomyces cerevisiae is considered as a potentially efficient cellular factory for dicarboxylic acid production.