The Effects of Antibiotics on Yeast Survivorship Chawrley Curr Grade 10 Pittsburgh Central Catholic High School

Candidiasis Commonly known as yeast infections Caused by uncontrolled multiplication of yeast cell Candida albicans in body Candida albicans can live in human mouths and in the gastrointestinal tract without causing harm Antibiotics and steroids use are most common reason for yeast infections Oral Yeast Infection

Nystatin Antifungal drug Used for treatment of yeast infections of the stomach, mouth, intestine and mucus membranes Attaches to ergosterol which is a major component of cell membrane Ergosterol is unique to fungi so nystatin does not have a catastrophic impact on animals

Saccharomyces cerevisiae Eukaryotic Reproduces by budding Most commonly studied eukaryotic model organism Top-fermented yeast

Ampicillin Penicillin antibiotic Used in treatment of bacterial and fungal infections Acts as competitive inhibitor of an enzyme and inhibits the final stage of cell wall synthesis and causes cell lysis

Materials: 60 YEPD agar plates ( Klett spectrophotometer Sterile pipette tubes Micropipettes 4 one liter beakers Vortex Incubator Sidearm flask Spreading platform Spreader bar Ethanol 20 mL Sterile capped test tubes with sterile dilution fluid (SDF) Ampicillin Nystatin Suspension

Procedure: Yeast was grown overnight in sterile YEPD agar media A sample of the overnight culture was added to fresh media in a sterile sidearm flask. The culture was placed in a shaking water bath (30°C) until a density of 50 Klett spectrophotometer units was reached. This represents a cell density of approximately 107 cells/ml The culture was diluted in sterile dilution fluid to a concentration of approximately 107 cells/ml The selected experimental variables were diluted with sterile dilution fluid to the chosen concentrations to a total of 9.9mL 0.1 mL of cell culture was then added to the test tubes, yielding a final volume of 10 mL. and a cell density of approximately 103 cells/mL The solution was mixed by vortexing and allowed to sit at room temperature for 15 minutes After vortexing to evenly suspend cells, 0.1 mL aliquots were removed from the tubes and spread on 60 plates The plates were incubated at 30°C for 12 hours. The resulting colonies were counted. Each colony is assumed to have arisen from one cell.

Purpose: Hypothesis: Null Hypothesis: To determine how various concentrations of antibiotics and antifungals affect yeast survivorship Hypothesis: Increasing concentrations of antibiotics and antifungals will result in the decrease of yeast survivorship Null Hypothesis: There will be no significant variation in yeast survivorship at all concentrations