Respiration In Yeast

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3.1,4.2 Metabolism-fermentation and respiration in yeast In this practical, we have to examine the growth of three different yeast strains which are Saccharomyces cerevisiae (S41), αpet1 and Yarrowia lipolytica (M240) in three different growth medium. Those medium are YEPA (yeast extract potassium acetate), YEPD (yeast extract peptone dextrose) and YEPO (yeast extract palm oil). These three different growth medium contain different nutrient content. For YEPA, it consists of potassium acetate, Bacto peptone, yeast extract and distilled water. While in YEPD, it consists of mainly glucose, Bacto peptone, yeast extract and distilled water. Otherwise for YEPO, it consisys of yeast extract as well as palm oil. Different type of nutrients contain…show more content…
Respiration in yeast happens when glucose is broken down to produce ATP, water molecule and release carbon dioxide in the presence of oxygen. This reaction can be summarized by the following equation : C2H12O2 + 6O2 6CO2 + 6H2O + ATP If the concentration of oxygen is depleted, it will commonly controls the switch from respiration to anaerobic fermentation. The net result of this process is ATP and produces 2 by product which are carbon dioxide and ethanol. After a week of incubation, we can observe the positive result of all the three strains in each growth medium. These positive growth are indicated by the cloudy appearance in the three…show more content…
During this experiment, Aspergillus niger and Yarrowia lipolytica are inoculated into YEPalm Olein broth medium and citric acid production medium. From the results, we can observe that there are many citric acid production in the citric acid production medium than in the YEPalm Olein broth medium. This is due to the lower pH in the citric acid production medium. Generally, a pH lower than 2 is required for optimum production of citric acid. Therefore, we can said that citric acid production medium is more ideal medium for the production of citric

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