Yeast Grows In Different Temperatures Biology Essay


The graph shows that the yeast grew best at 40 degrees than at 50 0r 30 degrees; around 500 (cells/ml -1000) were produced at 0 minutes when under the conditions: 40 degrees and 30 degrees, whereas only 222(cells/ml -1000) were produced when put under 50 degrees. However, when put under 50 degrees after 30 minutes, it is clear that the cells increased by 111 to give 333(cells/ml -1000) and under 30 degrees at 60 minutes, the amount of cells growing decreased for all levels excluding the conditions at 40 degrees (250 cells were produced).

Based on the results from the investigation; I would recommend that when looking at the best leaving and growing conditions for yeast, it is important to consider everything so that you ensure that the yeast gets balanced growing conditions.

Looking at the results from the investigation, it is clear to say that yeast needs an optimum temperature as well as the right amount of oxygen to maximise growth. When the temperature is too low, the yeast will struggle to grow and when it is too high the enzymes of the yeast will begin to denature which slows down their growth levels.

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My results indicate that although some of the yeast grew quite well at 30 degrees; 40 still seems like the most adequate optimum temperature for the yeast growth. At 0 minutes about 500 (cells/ml-1000) grew when under 30 and 40 degrees Celsius, but then slowly dropped down to 286 (cells/ml-1000) at 30 minutes whilst the 50 degrees moved from 222 (cells/ml-1000) and pushed to 333(cells/ml-1000). The yeast cells under 40 degrees maintained their growth levels and continued to grow producing 250 (cells ml-1000) at 60minutes above 50 degrees with about 200(cells/ml-1000).

From what is indicated, it is fair to say that the yeast struggled to grow at both 30 and 50 degrees than it did at 40. However, based on the evaluation of the results, it is still not clear as to whether 40 degrees is the final and definite temperature that yeast needs to grow properly. Further tests may need to be done to clarify this result.

Likewise, the results have clarified that yeast grows better under oxygen than it does without oxygen. However, the results also show that the rate and the amount of time that yeast is exposed to air has an effect on its growth; it needs not too little (exposed to air for short periods) and not too much oxygen (exposed to air for long periods).

Looking at the graph, we can see that from 0 to 30minutes, 500 (cells/ml-1000) were produced when under oxygen and only 286(cells/ml-1000) were produced without oxygen. Despite this, at 45 and 60 minutes the rate of growth begins to drop rapidly when under oxygen than it does without oxygen, so there is an increase in growth of cells without oxygen because the yeast has had more exposer than needed and therefore has slowed down its growth level with oxygen than without oxygen which makes it clear that although yeast needs oxygen, it does not have to have too much.

The main reason why companies which make products from micro-organisms maintain optimised growth conditions is to make money and increase their profit; the companies have to make sure that the conditions have an optimum temperature, the same amount of oxygen, pH levels and nutrients. When these things are kept the same at an optimum level, the micro-organisms being cultured will thrive and grow faster allowing the companies to sell more products that are of good quality and make a profit.

The main equipment used for the large scale growth of yeast in the biotechnology industry, are fermenters (small, pilot and commercial).After the yeast production process were the yeast is matured, the now matured yeast will then be taken and stored in small fermenters that look like tanks to allow it to continue to multiply in number. As it continues to multiply, It will be moved to pilot fermenters and then onto the largest fermenters which can take up to 50/ 60,000 gallons.

Although the process of fermentation involves only anerobic energy to culture micro-organisms, when oxygen (aerobic) is present the yeast oxidises into carbon dioxide and water which can then be made into alcohol.

During the process of fermentation, there are several variables that need to be controlled in order to produce the maximum yield of yeast, these include:

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The Oxygen which is basically sterile air in the atmosphere comes through at the bottom of the fermenter in a form of bubbles (sparger); when the yeast culture has received the required amount of oxygen, it will oxidise to form carbon dioxide which comes out of the fermenter as steam. As a control, if the oxygen becomes too much or too little than needed, the sterile seal will seal the area were oxygen is being produced to enhance culture growth.

The optimum temperature is maintained using the motor which spins around with the yeast culture; where there is cold air from the oxygen, the motor will change direction so that the yeast will receive the same level of temperature causing it to produce steam.

To control the pH, the fermenter will use the acid base reservoir pump to pump out the right amount of pH that is required for the culture.

Nutrients such as: starch, sugar, acid, minerals and nitrogen will also be produced under optimum conditions with oxygen.

After the fermentation process has worked, the yeast is separated from all the other products and used for different manufacturing processes in the industry.