Experimental Design to Determine the Most Effective Yeast for More Ethanol Production - Lab Report Example

Name: Instructor: Course: Date: TITLE: Experimental design to determine the most effective yeast for more ethanol production Aim of the Study To expose sugar cane juice to different types of yeast to determine which one produces more ethanol and the reasons for the difference. Background Sugar cane is grown in many countries as a cash crop but for countries like Brazil, it has a major function including production of ethanol for fuel (Moreira 2000,EIA 2008). The part of the sugar cane that is used is the sugarcane juice which contains a lot of organic nutrients that aid in the normal fermentation using Saccharomyces cerevisiae to produce ethanol. The juice is collected through pressing of the sugarcane in a mill. (http://en.wikipedia.org/wiki/Sugarcane_juice) For effective fermentation high temperatures are required hence a mesophilic strain of S. cerevisiae is used. Rapid fermentation is practiced at the high temperature to avoid or minimize chances of contamination. Other thermotolerant strains of yeast have been isolated to aid in the ethanol production over the years including Kluyveromyces marxianus (Zafar and Owais 2006) and Pichia kudriavzevii (Dhaliwal et.al 2011) . Methodology The requirements included; The brewing yeast, Turbo yeast and Largen Yeast. Processed sugarcane juice,100ml beakers, 150ml conical flask, burner triple, funnel, coffee filter papers, heat mat, cotton buds alcohol meter and an oven. Procedure 1 To ensure that the sugarcane juice did not contain any yeast prior to the experiment, it was taken through an experiment of fermentation at high temperature of 400C. The sugarcane was filtered using the coffee filters, it was then transferred to 4 150ml conical flask and three of the flasks were heated up to 400C. In one flask the top yeast (S.cerevisiae) was added while in the other one the bottom yeast (S.carlsbergenesis) was added, one flask was left as a control with no yeast added. The flask that was not heated was put at room temperature while the others were incubated for three days. Procedure 2 The sugarcane juice was filtered through use of coffee filter papers and collected in 100ml beaker containers, the filtered juice was then transferred to the 150ml conical flask and it was heated up on the triple burner until the required temperature was attained, a measured value of 0.05g of the different yeasts (S.cerevisiae, turbo yeast and Largen yeast) were added to the flasks and covered with cotton buds and put in the oven for 4.5hours for the process of fermentation and ethanol production. Results In the first experiment, the sugarcane that was not heated showed signs of fermentation, while the one flask that did not have any yeast added to it recorded a minimal 0.1% alcohol content. The flask with the top yeast had an alcohol content of 2.2% while the bottom yeast had 1.22%. The results are represented in the table below Value of yeast Alcohol Type if yeast Temperature(oven) Period 1 0 0.1% Nature/no yeast 40℃ 3 days 2 0.05g 2.2% Top yeast 40℃ 3 days 3 0.05g 1.22% Bottom yeast 40℃ 3 days 4 0 fermenting Nature/no yeast Room temperature 3 days In the second experiment, the flask with the brew or S.cerevisiae yeast had an alcohol content of 9.89% while the turbo and Largen yeasts had 3.2% and 0.9% respectively while the control flask recorded zero alcohol content. The results are represented in the table below Value of yeast Alcohol Type if yeast Temperature(oven) Period 1 0.05g 9.89% Brewing yeast 400C 4.5 hours 2 0.05g 3.2% Turbo yeast 400C 4.5 hours 3 0.05g 0.9% Largen yeast 400C 4.5 hours 4 0 0% No yeast 400C 4.5 hours Discussion Fuel ethanol is currently produced through large scale yeast fermentation of sugars. S.cerevisiae has been used for a long time in fermentation of sugarcane juice especially in the major fuel ethanol producing countries, Brazil and North America.(Wheals et.al 1999) The sugarcane in itself contains a lot of nutrients that provide a culture medium for growth of the yeast. Hence in the natural environment, a test of the sugarcane products will reveal presence of the yeast S.cerevisiae. A thermo resistant type of the yeast known as the mesophilic strain was preferred due to its heat resistant quality in use of high temperatures. In the first experiment, the thermoresitant type of S.cerevisiae and S.carlsbergenesis were used. There was a difference in the ethanol production between the two types of the Saccharomyces strain. The difference between the two strains is the surface phosphate concentration. Research has shown that the top-fermenting strain was found to be more hydrophobic and negatively charged than the bottom fermenting strain (Amory and Rouxhet 1988). The higher the temperature the lower the carbon dioxide solubility and thus an increase in carbon dioxide leads to an increase in the amount of ethanol produced (Jones and Greenfield 1982). According to Dengis et.al (1995) the bottom-fermenting strain was found to contain a hydrocarbon-like carbon and more oxygen hence the production of ethanol is limited as it does not need to break down the sugars to get energy unlike the top-fermenting strain that has less oxygen hence breaks down the sugars and in the event produces ethanol (http://microbewiki.kenyon.edu/index.php/Saccharomyces_cerevisiae). Thus this explains the difference in the quantity of ethanol produced.An example of the top and bottom fermenting strains are illustrated below; B= bottom-fermenting strain T= top-fermenting yeast strain The S. cerevisiae yeast occurs naturally and thus can explain why the cane juice that did not have yeast added into it, started fermenting in room temperature, this can be seen even in baking yeasts left in room temperature begin to ferment. In experiment 2, the S.cerevisiae produced more alcohol than the turbo and Lager yeasts. This was the top fermenting strain so the high production was expected. The lager yeast is a bottom fermenting yeast and thus the low quantity of ethanol produced. The Turbo yeast is a combination of heat tolerant yeast strain and additional nutrients that ferment sugars in alcohol. (http://turbo-yeast.com/introduction/) Though a temperature of 400C can result in killing of the yeast, the more the alcohol produced the more the killing temperature reduced.( http://turbo-yeast.com/all-about-temperature/) The control had no yeast added to it and as such did not have any alcohol production, any natural occurring yeast was destroyed in the high temperature. Conclusion For successful ethanol production, it is paramount that the amount of oxygen be reduced to nil to enable fermentation take place in a faster rate. The high temperature can cause damage or kill the yeast but research has shown the more the yeast produces alcohol the lower the temperature gets hence ensuring the survival of the yeast. After the experiment, the top fermenting strain of S.cerevisiae has emerged as the more effective yeast to produce large amounts of fuel ethanol. Positive and Negative Impacts of Ethanol production Sugarcane fuel has been recommended due to its positive impacts including its environment friendly due to its use in gasoline that lead to the complete elimination of lead compounds and no noxious emissions.(Goldemberg,Coelho and Guardabassi 2008) It is also a renewable fuel as it only requires a small amount of fossil fuel for its processes, hence reducing the carbon dioxide emissions. It has also the negative impacts on the environment including decarbonization of the soil, deforestation due to large scale production of the sugarcane, competition between food and fuel production leading to food insecurity (ESMAP, 2005) .Unlike Jacobson (2007) who saw the use of fuel ethanol as a potential risk to diseases like cancer, Saldiva (2007) indicated that the ethanol fuel enabled elimination of more potent dangerous chemicals emitted by the other forms of fuels. Due to this negative impacts it is important that the environment is preserved even as we venture into clean fuel many legislative laws were introduced to enable the sustainability of the production as well as preservation of the environment (Goldemberg, Coelho and Guardabassi 2008). References 1. Amory, D. E. and Rouxhet, P. G. “Surface properties of Saccharomyces cerevisiae and Saccharomyces carlsbergensis: chemical composition, electrostatic charge and hydrophobicity”. Biochim. Biophys.Acta 938 (1988), 61–70 2. Anonymous: About turbo yeast, available [online] http://turbo-yeast.com/all-about-temperature/Dengis, Pascale B., and Paul G. Rouxhet. "Surface Properties of Top‐and Bottom‐Fermenting Yeast." Yeast 13.10 (1997): 931-943. 3. Dhaliwal .Singh S et.al “Enhanced ethanol production from sugarcane juice by galactose adaptation of a newly isolated thermotolerant strain ofPichiakudriavzevii” Bioresource Technology 102 (10) 2011, Pages 5968–5975 4. Energy Information Administration (EIA—Official Energy Statistics from the US Government), 2008. Oxygenate production. Accessed on January 2008. 5. ESMAP, Potential for Biofuels for Transport in Developing Countries Energy and Water Department, World Bank, Washington, DC, USA (2005) p. 182 6. Goldemberg, José, Suani Teixeira Coelho, and Patricia Guardabassi. "The sustainability of ethanol production from sugarcane." Energy Policy 36.6 (2008): 2086-2097. 7. Introduction into turbo yeast; available [online] http://turbo-yeast.com/introduction/ 8. Jacobson M.Z “Effects of ethanol (E85) versus gasoline vehicles on cancer and mortality in the United States” Environmental Science and Technology (2007) 9. Jones, Rodney P., and Paul F. Greenfield. "Effect of carbon dioxide on yeast growth and fermentation." Enzyme and Microbial Technology 4.4 (1982): 210-223. 10. Moreira JR. “Sugar cane for energy recent results and progress in Brazil” Energy for Sustainable Development, 17 (2000), pp. 43–54 11. Student edited microbiology resource, available [online] (http://microbewiki.kenyon.edu/index.php/Saccharomyces_cerevisiae) 12. Saldiva, P. Personal communication, 2007 April. 13. Wheals, Alan E., et al. "Fuel ethanol after 25 years." Trends in biotechnology17.12 (1999): 482-487. 14. Zafar, M. Owais Ethanol production from crude whey byKluyveromyces marxianus Biochemistry Engineering Journal, 27 (2006), pp. 295–298. Read More