Yeasts way to survive under particular nutritional conditions

Yeasts are single cell microorganisms that grow only under certain conditions and have a variety of unique properties. Certain types of yeasts such as Saccharomyces cerevisiae are facultative anaerobes, which are bacteria or fungi organisms, that are able to change their metabolism to grow either with or without the presence of oxygen, (Facultative anaerobes, 2017). Majority of yeasts need an abundance of oxygen (aerobic conditions) as well as the presence of a basic substrate such as sugar to grow (Battcock & Ali, 2000). Sugars can be fermented into alcohol and carbon dioxide without air, however, the yeast won’t increase in mass  (Battcock & Ali, 2000). Glucose and fructose allow the yeast to produce ethyl alcohol and carbon dioxide. The growth and behavior of yeast cells alter in correspondence to the amount of nutrients available (Broach, 2012). Nutrients supply not only the substrates required for growth, but also the signals for growth, meaning that nutrients allow the cell to increases its mass and generate energy to advance its biosynthetic activity and also signals the metabolic, transcriptional, and developmental agenda that create the most effective way to survive under particular nutritional conditions (Broach, 2012). Yeasts can adjust their growth rate in response to their nutritional environment by modifying the length of their cell cycle to ten times the length (Brauer et al. 2008 in Broach, 2012). In terms of temperature, yeasts perform best in the 0 to 50° C range, with the optimum temperatures being 20° to 30° C (Battcock & Ali, 2000). Yeasts are able to tolerate growth in acidic pH conditions of 4 to 4.5 and most require a minimum water activity of 0.85 or a comparative humidity of 88% (Battcock & Ali, 2000). Battcock and Ali (2000) found that yeasts can tolerate solutions with concentrations of sugar as high as 40%. However, at concentrations higher than this, only osmophilic yeasts can survive in 65 -70% concentrations of sugar, as these yeasts grow very slowly (Board, 1983 in Battcock & Ali, 2000). Types of yeasts that can tolerate high salt concentrations and low water activity include Debaromyces and Zygosaccharomyces rouxii (Battcock & Ali, 2000). Glucose, also called dextrose, is a monosaccharide containing six carbon atoms and an aldehyde group, with the molecular formula C6H12O6 (Glucose, 2017; D-Glucose, 2018 ) Glucose is found in fruits and other parts of plants in its free state (Glucose, 2017; D-Glucose, 2018) In animals, glucose surfaces from the decomposition of glycogen in a process known as glycogenolysis and is the major free sugar circulating in the blood of higher animals (Glucose, 2017; D-Glucose, 2018). It is the primary source of energy in cell function, and the regulation of its metabolism is significant (Glucose, 2017; D-Glucose, 2018).  Sucrose (C12H22O11) is a disaccharide composed of fructose and glucose, its two essential monosaccharides, linked by their anomeric carbons (Sucrose, 2017; Sucrose, 2018). Industrially, it is obtained from sugarcane, sugar beet, and other plants,and utilised primarily in food as a sweetener (Sucrose, 2017; Sucrose, 2018). In living plants and fruits, sucrose functions as energy storage for metabolism, and as a carbon source for biosynthesis (Sucrose, 2018).