Bio Mini Project The Effects of Different Type of Food source on the Growth rate of Saccharomyces Cerevisiae - Vilasini a/p Karthikesan (16UHF04796) - Joey Tay Ruo Yi (16UHF04659) - Suarnamughy d/o Maran (16UHF01984 )

1.0 Introduction What is yeast ? Yeast is unicellular cells which is a type of bacterial with species name of Saccharomyces Cerevisiae.The yeasts are eukaryotic, single-celled microorganisms classified as the members of fungi kingdom.The reasons for this classification are because it has chitin cell wall and the lipids are made up of ester linkage

1.Yeast with orange juice The orange juice has higher percentage of sugar, low pH value from 3.3 to 4.19 (Journal of Dentistry,2006) and 139 percent of the DV for vitamin C which is an acid.This conditions is more suitable for the growth rate of Saccharomyces Cerevisiae.Thus, it has the higher growth rate of bacteria.

2.Yeast with milk Milk contain 90 percent of water by weight which produce the moisture they need for bacteria growth, high sugar content called lactose which will metabolize the bacteria to provide the energy for bacteria reproduction and also rich in protein which increase the rate of bacteria.

3.Yeast with honey Honey is found in natural form which has very low moisture where only a few amount of bacteria can survive in this conditions,high percentage of fructose sugar which are hygroscopic where they don' t contain water in their natural form and low pH value from 3.26 to 4.48 that kills any bacteria growth (Amina Harris, n.d).

2.0 Materials and Methods

15 ml of orange juice is measured out in measuring cylinder. Poured the solution into universal bottle with the portion of dry yeast close it and leave 30 mins at 37.c. 4 portion of 0.5 g dry yeast is weighed. ↓ ↓

Placed the solution on the solidified nutrient agar contained by petri dish. Hockey stick is used to spread the solution on the nutrient agar and the lid of petri dish is placed back. 2ml of solution is taken out using inoculating loop from the universal bottle. ↓ ↓

Petri dish will be left to incubate for 1-3 days. The experiment is observed and recorded- number of bacteria growth. Above steps are repeated with milk and honey. The experiment was conducted with 3 set of nutrient agar for each food sources. ↓ ↓

3.0 Expected Results Manipulated variable : Different type of food sources Responding variable : Growth rate of yeast Constant variable : The temperature of food sources, Amount of Saccharomyces Cerevisiae, Volume of food sources

Table 1: Average number of bacteria produced with different types of food source. Experimental Set ContentsAverage Number of Bacteria found in 1 cm 3 Final Number of Bacteria produced in Petri Dish Yeast with nutrient agar Yeast with orange juice Yeast with milk Yeast with honey