Payal PatelLab Communication 3Section 16Group 4Yeast Biofilm and It’s Growth MediumIntroductionBiofilms are groups of an organism or many organisms that stick to organic and non-organic sources. It has been shown that although these cells are not of the same organism or species, they communicate with one another, as a multi-celled organism would do. They grow, share resources, and often have set functions for the better of the biofilm. Yeast is used for the production of alcohol such as wine. This is because the yeast ferments with a carbon source to produce an alcohol byproduct (Hall-Stoodley, Costerton, Stoodley).From the background information that was collected, it was hypothesized that lactose would be a better growth medium for the yeast than glycerol because it goes through the carbohydrate metabolism rather than an alternate pathway such as lipid biosynthesis. So the prediction was that lactose would have more overall growth of the yeast than glycerol.MethodsIn the experiment, the control was the dextrose plate. The variables manipulated were thecarbon source, which was the independent variable, and the amount of growth in each of the four strands of yeast used, the dependent variable. There were 2 replicate plates of lactose and 2 replicate plates of glycerol with only one control dextrose plate. All were inoculated in the same fashion with the same strains.From the initial observations, there was the observation that 0.3% agar plates had more growth of yeast than the 0.2% agar plates and the sacc wild type had the most growth overall. 5 measurements were taken of each strain on the 0.3% agar plates: pH of agar on the edge of the plate, pH on the edge of the biofilm, pH in the center of the biofilm, diameter of the biofilm in millimeters, and the adhesion overlay test. The plates were inoculated and incubated at 37 degrees Celsius for seven days then measured. To make sure there were no discrepancies, the diameter of the biofilm was taken in two perpendicular directions and averaged because some of the biofilms were not perfectly symmetrical circles. The adhesion overlay test was used to show the hold of the biofilm onto the substrate. To test with this method, plastic wrap was used. It was gently laid overthe biofilms in the plate, and when gently pulled off, some of the biofilms clung to the plastic and came off, whereas, others stayed completely or partially intact on the plate.ResultsThe lactose plates were found to have the more growth than glycerol. A correlation between the pH and growth was not found because a byproduct of the metabolism of yeast is alcohol and that is not related to acidity of basicness of the biofilms. The sacc wild-type yeast had the most overall growth and adhered well to the agar when the overlay adhesion test was performed. The range of the pH on the lactose plates was 6-6.5, dextrose: 4.5-6, and glycerol 5-5.5.5.75.85.966.16.26.36.46.56.66 26.25Wild Type pHGlycerolLactoseDextrosepH01234567TRY 138 WT pHGlycerolLactoseDextrosepH5.75.85.966.16.26.36.46.56.66.56 6TRY 143 - hyper flo pHGlycerolLactoseDextrose55.25.45.65.866.26.4TRY 140 - hypo flo pHGlycerolLactoseDextrose05101520253035Wild Type growthGlycerolLactoseDextrosediameter (mm)051015202530TRY 138 WT growth GlycerolLactoseDextrosediameter (mm)02468101214161820TRY 140 - hypo flo growthGlycerolLactoseDextrosediameter (mm)024681012141618TRY 143 - hyper flo growthGlycerolLactoseDextrosediameter (mm)DiscussionBased on the results, the hypothesis was supported because lactose had more growth thanour non-fermenting carbon source, glycerol. To test this same hypothesis in the future, it would be ideal to use more replicates of each carbon source and a more variable number of carbon sources. Lactose was decided to be more ideal for fermenting because glycerolis a non-fermenting source. This is because it is an alcohol that is a byproduct of fermentation rather than a starting product.References CitedSchussler, Elisabeth, Jan Hudson, Erica Rowe, Monique Lemieux, and Sudhir Naswa. Biology 140 Lab Manual. Knoxville, TN: University of Tennessee-Knoxville, 2012. 17-22. Print.Hall-Stoodley, Luanne, J W. Costerton, and Paul Stoodley. Bacterial Biofilms: From the Natural Environment to Infectious Diseases. 95-106.