1. Growth Of Yeast Bio- films By Raykia Koroma

2. Background Information There is a species of yeast cell called Saccharomyces cerevisiae that is commonly known as Baker’s Yeast. In the lab I am working with Saccharomyces cerevisiae has been genetically engineered to express the ALS5 gene from another yeast called Candida albicans. Candida albicans is a fungus that causes yeast infections that infect 10 out 1000 people a year. It also kills hundreds of AIDS victims and cancer victims a year. It only attacks people with suppressed immune systems which means it is an opportunistic pathogen. Candida albicans expresses 6,000 genes one of them is ALS5. ALS genes encode an adhesion glycoprotein. There are 8 different ALS genes: ALS1-ALS7 and ALS9.

3. Purpose I want to know if I express this ALS5 protein would I get a different or better type of biofilm. If yes what does it mean? Is ALS5 important for the growth of the biofilm?

4. Materials Plates Flask Incubator Autoclave YPA agar media Csm-URA agar media Csm-Complete agar media W3031B ALS5 ALS1 Strains ALS3 PADH Shaker Pipette Gloves Csm-URA liquid Csm- complete liquid Spectrophotometer

5. Methodology I made 500ml of YPA, Csm- URA and Csm- Complete agar media’s. Split each media into 4 different flasks that contain 125ml in each with - 2% agar w/galactose -.3% agar w/galactose - 2% agar w/glucose -.3% agar w/glucose Autoclaved them for 25 minutes. Poured them on plates and left them overnight in a 30 degrees C incubator. Streak -ALS5 on Csm-trp -W3031B on YPED -ALS1 on Csm-URA -ALS3 on Csm –URA -PADH on Csm-URA Inoculated the strains into flasks and put them in a 30 degree C shaker Measure their Optical Density(OD) If they all reach.5 great but if not then I would have to spin them down for about 10 minutes. Dilute so that it’s 3.3 x10 6 cells/ml 2 using the Dimensional Analysis technique. Then inoculate on plates that are divided into either 3 or 2 sections: -ALS1, ALS3 & PADH same plate with glucose only -W3031B & ALS5 same plate with glucose or galactose Leave them to grow at room temperature to grow for about a week Analysis will be based on the appearance of the biofilm

6. Results No results as of yet. I’m expecting for W3031B and PADH to look like ALS1 and ALS3 should be a moderate size and be constitutively on. ALS5 should grow better on galactose and should look like

7. Acknowledgements Dr. Peter Lipke Janice Lee Marlyn Gonzales Raymond Fung Dr. Sat Bhattacharya Harlem Children Society Staff Brooklyn College