Saccharomyces cerevisiae – Term Paper

How do honey (strained honey), aloe vera, urine, and saliva affect the respiration rate of Saccharomyces cerevisiae? 

Background Information

China is one of the states with the longest period of history. Beginning with the Shang Dynasty till present, China has been creating and inventing numerous materials including paper, gunpowder, and the compass among others. The most intriguing development is the Chinese medicine which uses, natural herbs. The incorporation of Chinese remedies into today’s medical practice is both astonishing and fascinating, especially without any scientific background. Examples of these traditional medicines include honey, aloe vera, urine, and saliva to relieve burns. Knowledge of these remedies and their application prompts my investigation on their use and reliability.

Respiration is a vital process for the survival of a living organism. According to Aberts et al., both eukaryotic and prokaryotic organisms perform cellular respiration to yield energy. Cellular respiration occurs in two ways, which include anaerobic and aerobic respiration (476). Prokaryotes are single-celled organisms lacking specialized organelles. Based on the absence of complex organelles, prokaryotes perform anaerobic respiration. The process takes place either across the plasma membrane or the cytoplasm. Comparatively, eukaryotic organisms carry out aerobic respiration through the mitochondria to produce sufficient energy for the efficient performance of the complicated process of the specialized organelles (453).

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Yeast cell, Saccharomyces cerevisiae, commonly known as baker’s yeast is one of the single-celled eukaryote frequently applied in scientific research globally. Genome sequencing provides that genes and proteins present in the yeast cells are human homologs allowing scientist to use it in place of the human’s cell (“Jove”). Therefore, I prefer to use Saccharomyces cerevisiae to replace human skin cell (Keratinocyte) in investigating the effectiveness of the four traditional healing solutions. 

Saccharomyces Cerevisia: Hypothesis and Explanation

The optimum pH of Saccharomyces cerevisiae is about 4 to 4.5. Honey displays antibacterial properties based on the presence of royalism, a potent antibacterial protein. The activity of the protein in honey works under a pH range of 3.2 to 5, attributed to the production of hydrogen peroxide H2O2. Comparatively, aloe vera has a pH of about 4.4 to 5.5 allowing it to display anti-inflammatory effects superior to 1% hydrocortisone cream or a placebo gel. Additionally, researchers claim that aloe vera gel may be useful in treating inflammatory skin conditions (University of Maryland Medical). Both honey and aloe produce positive results in treating burns. However, Saccharomyces cerevisiae works better in aloe owing to the lower pH range of aloe. Therefore, aloe vera is the best solution to regenerate cells.


Variables (Independent, dependent, control, uncontrolled)

(discuss) Likely impact upon the investigation

How the variable will be changed/ measured/controlled

Independent variable

Different solutions


Affect the respiration rate


·        Using measuring cylinder to measure the amount of solution

Dependent variable

The respiration rate of Saccharomyces cerevisiae in a different solution.



Indicates effect of different solution on Saccharomyces cerevisiae



·      Using syringe

Control variables

The amount of yeast

The amount of solutions

The timing of stopwatch


Affects the respiration rate of the Saccharomyces cerevisiae.


·      By using measuring cylinder

Uncontrolled variables

The varieties of Saccharomyces cerevisiae


Different species may react differently on the test solutions.


·      It will affect the dependent variable.

·      To minimize the effect by using measuring cylinder.


Measuring cylinder ( )

Gas syringe ( )


Balance ( 

Stop watch 


1. Prepare 10g of honey, aloe, saliva and urine.

2. Pour 50cm3 of deionized water into four conical flasks, label them with A, B, C, D.

3. Mix A with 10g of honey, B with 10g of aloe, C with 10g of saliva, D with 10g of urine. 

4. Stir A, B, C, and D with a glass rod separately.   

5. Attach one end of the delivery tube to a rubber bung.

6. Attach the other end of delivery tube to a gas syringe.

7. Using a stand and clamp, secure the gas syringe horizontally onto the clamp. 

8. Prepare 1.00g of Saccharomyces cerevisiae in a weighing boat on an electronic balance. 

9. Pour 1.00g of Saccharomyces cerevisiae into the conical flask A.

10. Make sure the conical flask A may be quickly and securely attached to gas syringe connected rubber bung.

11. Make sure gas syringe is set to indicate 0 cm3.

12. Start the stopwatch and take the initial reading of gas syringe.

13. Take the reading of gas syringe every 15 minutes for 1 hour and 30 minutes.

14. Repeat the procedure 5-13 by using the conical flasks B, C, and D.

15. Record down the index.

16. Repeat the steps 5-13 five times and gather all the data.

Saccharomyces Cerevisiae Facts: Safety and Ethical Considerations

Based on the possible hazardous effects of the test solutions, it is necessary to handle them efficiently to minimize their effects on the individual performing the experiment and the environment. Human urine produces ammonia which odor is non-pleasant; therefore, to reduce the diffusion of the odor, air tight containers are most appropriate to handle urine. Additionally, body fluids pose a biological threat based on the numerous virus and bacteria present. Additionally it is necessary to wear appropriate Personal Protective Equipment (PPE), especially to the individual performing the experiment. 



Table1: Amount of gas volume produced in respect to time and type of solution







90  min








Aloe vera





















According to Aberts et al., cellular respiration occurs through a series of actions beginning with glycolysis, which is the splitting of sugar molecules for the production of Adenosine Triphosphate (ATP). Conversion of glucose into pyruvate involves two phases requiring the use of enzymes. The first phase requires the intake of energy allowing for the rearrangement of the sugar molecules and the attachment of phosphate on either end of the molecule (469). The unstable molecule, usually fructose-1, 6- bisphosphate formed from glucose splits into two phosphates carrying three carbon sugars. The second phase involves the release of energy from the sugars formed in the previous steps. The reactions of the second phase lead to the production of two molecules of ATP and one of Nicotinamide Adenine Dinucleotide (NADH) illustrated by the equation below.

C6H12O6+ 2NAD + 2ADP+ 2P                     2 pyruvic acid, (CH3(C=O) COOH+ 2ATP + 2 NADH+ 2H

In regards to Lushchak et al., Krebs cycle follows glycolysis leading to a complete breakdown of the sugar and the release of carbon dioxide. The process releases energy through the electrons moving across the mitochondrial membrane (9). Additionally, it utilizes acetyl coenzyme A (CoA) a product of the oxidation process of the pyruvate. Acetyl-CoA associates with carbon accepting molecules forming citrate, which is a six-carbon molecule. Re-arrangement of the molecule releases two of its carbon particles producing carbon dioxide and NADH. The other four carbons undergo various chemical reactions leading to the formation of ATP, the reduction of the energy carrier from Flavin Adenine Dinucleotide (FAD) to Flavin Adenine Dinucleotide FADH2 and NADH. The final step in respiration is the movement of charged electrons through the mitochondrial membrane. Consequently, the movement results in attraction of oppositely charged molecules leading to the production of ATP, the primary source of energy.

Effects of Honey on the Respiration Rate of Saccharomyces Cerevisiae Infection

Saccharomyces cerevisiae belongs to the yeast family one of the eukaryotic organism. Yeast absorbs sugar breaking down the molecules into simple sugars such as the monosaccharides and generating the energy-rich ATP. According to Kwakman, Paulus, and Sebastian, honey comprises of the sugars fructose, glucose, and sucrose. Sucrose is a disaccharide composed of the sugar glucose and fructose. The breaking down of sucrose into glucose involves the enzymes sucrase and isomerase. Sucrase facilitates the splitting of sucrose into fructose and glucose. Comparatively, enzyme isomerase converts fructose into glucose for respiration (49).

The mechanism of the enzyme sucrose involves a process referred to as hydrolysis requiring water to break the chemical bonds. Acidic conditions enhance the process of hydrolysis separating the hydrogen molecule from the water molecule. The equation below illustrates the process leading to glucose formation.

C12H22O11+ H2O                       C6H12O6+ C6H12O6

Respiration involving the use of honey produces more glucose resulting in significant energy levels. Additionally, there is an increased production of carbon dioxide caused by the breakdown of glucose to release energy. Although the process begins at a slow rate, it proceeds with a rapid production of carbon dioxide and later reduces to the minimum production of the gas as the products of fermentation increase. Table1 illustrate the performance of honey about the volume of gas with respect to time. An increase in osmotic concentrations of the sugar reduces the amount of water necessary for the growth of the yeast. Consequently, increased sugar levels shift the movement of water in the yeast cells.

In regards to Bento et al., the exponential growth rate of the yeast cells provides high and rapid metabolism. The characteristic of the process begins with an oxidative phase during the exponential period and increased fermentation towards the end of the phase (3). Variations in carbon dioxide production with time provide the evidence for the different characteristic of the growth phases of the yeast cells. Additionally, decreased respiration across the exponential growth rate indicates changes in the metabolism process with an increase in fermentation. The data on honey and the amount of gas volume produce presents a typical example of changes in rate of respiration as metabolism of the sugar proceeds.

It is imperative to consider the pH of honey as a factor affecting cellular respiration rate. Saccharomyces cerevisiae thrives best in an acidic condition within the ranges of 4 to 4.5. Comparatively, honey contains both organic and amino acids influencing its pH range of 3.9 to 6.1. Organic acids include acetic, lactic, citric, formic and gluconic acid. Additionally, it is found to contain aromatic and aliphatic acids. The acidic properties of honey enhance its use in medicine, especially in inhibiting the growth of the microorganism. As respiration progresses, release of carbon dioxide lowers the pH enhancing the activity of the yeast cells. Comparatively, the increased acidity discourages the performance of enzymes significantly reducing the amount of glucose present in the cells and limiting the amount of energy produced. 

Effects of Aloe Vera on the Respiration Rate of Saccharomyces Cerevisiae Disease

The aloe vera plant provides numerous benefits as a result of its antibacterial properties. According to Marzieh et al., it promotes the growth of cells facilitating its use in the study (367). As for the chemical composition of the plant, it consists of vitamins, enzymes, sugars, amino acids, and minerals. The enzymes, with examples of the amylase, lipase, and acidic phosphatase contribute to digestion of particular biochemicals. The sugars comprise of both the monosaccharides and the polysaccharides originating from tissue layer neighboring the parenchyma tissues.

The structure of the polysaccharides found present in aloe vera consists of long chains of mannose and glucose. Molecules of the mannose sugar occur in two forms of either the pyranose or the furanose structure. The metabolism process of the sugar involves the process of phosphorylation using the enzyme hexokinase yielding mannose-6-phosphate. Consequently, mannose-6-phosphate under the influence of the enzyme phospho-mannose isomerase leads to its conversion to the fructose-6-phosphate that undergoes glycolysis to produce glucose and the waste products of either anaerobic or aerobic respiration.  The breakdown of the polysaccharides in the Aloe Vera produces greater amounts of glucose resulting in increased energy levels in the cells. Results in Table 1 indicate that aloe vera produces the largest volume of the gas a result of metabolism of the polysaccharides present. According to Marzieh et al., in a study on the effects of Aloe Vera on fish skin cells, the plant increases the skin thickness. Additionally, the plant creates a hydrated and viscous environment around the mucosa cells and the epidermal cells creating a barrier to entry of pathogenic components to the body of the organism (369). The outcome of the research indicates that with increased doses of the plant concentration, the cell density increases enhancing the defense mechanism against the pathogen. Comparatively, Pranab, Ajit, Gogoi and Neeraj describe that both Aloe Vera and yeast are medicinal plants incorporated into the feed to enhance immunity (93). Study on the effects of the plant and yeast in the development of muscle indicates that yeast promotes the development of normal flora. It alters the rate of metabolism through the action of the enzymes to improve the digestion process. Comparatively, Aloe Vera through the presence of the flavonoids provides an increased rate of metabolism increasing the levels of glycogen in both the liver and muscles (95).

Based on Tan, Benny, and Vanitha, the polysaccharide in Aloe Vera, acemannan, modulates the immunity in the host cells. The structure of the polysaccharide includes β (1, 4)-linked acetylated mannans, which act to increase phagocytosis (1425). The presence of polysaccharides, flavonoids, and proteoglycans in Aloe Vera influences their application in medicine to prevent the activity of microbes on the host cells (1427). About the pH level of Aloe Vera and its effects in influencing respiration rate in yeast, the plants’ pH range is 4.5 to 5.5. Its pH range enhances the activity of the yeast cells through providing an optimum pH for processes such as metabolism and respiration. The value corresponds with that of the skin providing a conducive and natural environment for the regeneration of cells. The acidic components of the plant promote the lower pH value limiting the activity of microorganism. 

Personal protective equipment (PPE) refer to equipment designed to reduce vulnerability of workers to serious injuries and illnesses which may result from contact with physical, chemical, electrical, or other hazards at workplace (Health and Safety Executive, 2013). Protective equipment includes gloves, earplugs, respirators, and protective glasses. PPE should only be used as a last resort when a hazard cannot be completely eliminated because it does not reduce hazard or give total protection (Health and Safety Executive, 2013). I t is the duty of employers to make the workplace safe for all employees, and employee safety can be guaranteed through training and supervision, providing instructions, use of safety procedures, and PPE. Type of PPE used is determined by nature of tasks and hazard exposure.

History of Anti Saccharomyces Cerevisiae PPE

Use of PPE as safety a safety measure was inspired by equipment used in military due to the dangers associated with war. History of PPE can be traced to several years back when soldiers wore full body armor, which included protective headgear and face gear, when fighting their enemies to protect them from being killed (United States Department of Labor, 2017). Blacksmiths also wore hand gear and aprons or shields back in the Middle Ages to protect them from molten metal they were working on. 

Initially, use of PPE was not compulsory and there were no regulations on employee protection until the enactment of the Occupational Safety and Health Act (OSHA) of 1970 (United States Department of Labor, 2017). The Occupational Safety and Health Act advocated for a countrywide protection of workers from work-related injuries in the U.S. In April 1971, the U.S. Secretary of Labor James Hodgson incorporated OSHA into the Labor Department with the responsibility of investigating and preventing work-related accidents, and defining appropriate PPE for every job description in a company (United States Department of Labor, 2017). PPE has advanced as a result of OSHA’s initiatives, and industries or individuals who aspire to ensure safety of their workers.

Hazards and PPE Used

Use of PPE varies depending on the type of hazard an individual is exposed to, and part of the body at risk of harm. Below are description of type of hazard, part of the body affected, and the PPE applicable in each case.

i. Whole body

Workers in different industries or companies can be exposed to hazards that can affect their entire body, such as excess heat, chemical splash, and leaks from spray guns (United States Department of Labor, 2017). In such a situation, boiler suits, chemical suits, aprons, and disposable aprons can be used to protect workers from injuries at workplace. Furthermore, materials used to make the PPE should be chemically impermeable, fire resistant, and clear for visibility. 

ii. Head and Neck

A worker’s head and neck are at risk of injuries from falling objects, extreme temperatures, hair getting tangled in machines, and head bumping. Hairnets, bump caps, industrial safety helmets, neck scarves, and firefighters’ helmet can be used to mitigate the injuries (United States Department of Labor, 2017). Tailor-made eye or ear protection can be fitted in the headgear, and damaged head protection should be replaced. 

iii. Eyes

Hazards that can harm eyes of workers and other individuals in industry environment include dust, gas, vapor, chemical splash, and projectiles. Employers and business owners can provide face screens, face shields, goggles, and safety spectacles to ensure no harm comes to individuals within their premises. The best eye protection should be effective and should fit the user perfectly.

iv. Ears

In an industry environment, especially manufacturing industries, operation processes produce high sound that may affect ears individuals close to the manufacturing plant or machine. Impacts of noise can be reduced by use of earmuffs, earplugs, and canal caps. The type of ear protector should correspond to the type of work, and should be able to reduce to acceptable levels while making communication possible (United States Department of Labor, 2017). In addition, the employer should ensure that employees know how to fit the ear protectors for effectiveness.

v. Hands and Arms

Most tasks in a company are performed using hands and arms, exposing them to risks such as to cuts, electric shocks, vibration, radiation, and scrapes. To reduce risk of injuries, employees can be provided with gauntlets, gloves, and long-sleeved wear that covers the arm. Safety measures to be observed by employees when using the PPE are; care in choice of glove used as not all gloves are fit for all conditions, avoid using gloves when operating machines because the gloves might tear, and avoid wearing gloves for a long period to avoid skin problems. 

vi. Feet and Legs

Employees’ feet and legs are exposed to workplace hazards such as slipping, cuts, falling objects, heavy loads, metal and chemical splash, and wet, hot and cold conditions. Safety boots and shoes with protective toecaps, foundry boots, and chainsaw boots can help in protecting feet and legs of individuals at the workplace. In addition, the type of boots worn should have sole pattern that can prevent slips in different conditions such as oil or chemicals.

vii. Lungs

Hazards that pose threat to lungs or respiratory system of individuals include gases, dust, vapors, and oxygen-deficient environments. Safety measure that can help in reducing risk of individuals developing lung problems caused by work environment the use of respiratory protective equipment such as face pieces, half masks, and full masks (United States Department of Labor, 2017).  Respirators used should have filters that are effective depending on the hazard an individual is exposed to, fit properly, and allow breathing. Breathing apparatus can also be used in areas with limited oxygen to avoid cases of losing consciousness.

Use of PPE

PPE can only serve its purpose when properly used, and used in the right situation. PPE should be designed in such a way that they are safe and comfortable to use and proper maintenance practice carried out to ensure that PPE are clean and in good condition. It is the duty of employers to provide PPE to their employees and ensure that the PPE are properly used by training employees on how to use and detect faults in PPE, when to use, and limitations to the type of hazard that a given PPE can protect them from. A company can implement a PPE program to look into company issues like hazards present, selection, maintenance, and use of PPE, training of employees, and constant checks on the program’s effectiveness. 

OSHA has set PPE standards for different industries such as construction, marine terminals, general industry, and shipyard employment, and requires PPE categories match standards established by American National Standards Institute (United States Department of Labor, 2017). Worker’s rights to PPE are protected by OSHA, and employees can complain to OSHA if they feel that serious hazards exist within their work environment and are not catered for by their employer.  To provide efficiency while using PPE, OSHA suggests that employers should ensure that PPE items that can be used together do not interfere with their individual performance, for example wearing goggles may interfere with respirator seal and cause air leaks.

When selecting PPE items for their employees, employers should have knowledge of the number of people exposed to a specific hazard, the duration in which they are exposed, and the volume or level of hazard in question.  PPE items available in a company should be enough to cover all employees who are at risk of injury or infection should be able to cover the employees for the duration they are working in a hazardous environment, and be able to withstand the volume of hazard an employee is exposed to. For example, a respiratory mask should have enough breathable air for the duration an employee will be stuck in an area of short air supply.

PPE Regulation.

Regulation of implementation of PPE and protection of workers is done out by OSHA.  OSHA requires employers to pay for employees’ PPE, and the PPE used comply with the set standards, and workers who have their own PPE can only use the equipment if it can adequately protect them from hazards at workplace (United States Department of Labor, 2017). Examples of PPE that must be provided by the employers include face shields, metatarsal foot protection, rubber boots with steel toes, and firefighting PPE. However, employers are not obligated to cater for some PPE such as daily long-sleeve clothing, long pants, winter coats, sun creams, and normal work boots. 

Employers should ensure that they adhere to the standards and regulations set by OSHA because contrary to this, they may attract penalties. A breach of work health and safety arises when a person is put at risk of injury, illness or death occurs, no steps are taken to avoid risky situations, and failure to comply with regulatory requirements (Queensland Government, 2017). Examples of breaches of workers’ safety are; working at with no control over risk of falling, allowing unskilled workers to operate machines, and exposing workers excessive noise.

Failure of companies to adhere to safety of their employees attracts penalties from OSHA depending on the magnitude of the offence (United States Department of Labor, 2017). An employer who intentionally and repeatedly violates workers’ safety may receive a civil penalty of $ 70,000 for each violation, an employer who has failed to correct safety violation attracts a penalty of $ 7,000, while a person who gives prior notice to a company about inspection to be conducted without permission from the secretary of OSHA is fined $ 1,000 or imprisonment for not more than six months. 

Employers and business owners should take measures to ensure that safety of employees and other individuals who visit company premises is guaranteed. Training employees on how to use PPE and constant monitoring and supervision of the implementation of PPE program is the best way to facilitate effectiveness of PPE items and promote employees’ safety. Employers should also avoid unnecessary charges on their companies by adhering to the regulations and standards of OSHA.