Potato Dextrose Agar Lab Report

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INTRODUCTION Fungi have been studied widely due to the increase in the incident of serious fungi infections such as systemic mycoses, subcutaneous mycoses, dermatophytes and superficial mycoses. The purpose of mycology is to determine the proper ways to treat and prevent the disease from further spreading. Basically, fungi are eukaryotic cells, chemoheterotrophs, aerobic or facultatively anaerobic, and the spore formation could be sexual or asexual. The kingdom fungi consist of the multicellular molds and unicellular yeast. Various yeast and molds are found to be the major factor that causes most of the food spoilage rather than foodborne illness. In fact, yeast and molds are less fastidious compared to bacteria especially pathogenic bacteria (James M. Jay, Martin J. Loessner, David A. Golden, 2005). Molds could grow on a variety…show more content…
Selective medium and low incubation temperature at 25°C is used. The selective medium that uses in this experiment includes the acidified potato dextrose agar (PDA), Dichloran Rose Bengal Chloramphenicol (DRBC) agar, and yeast and mold agar (YMA). Acidification of the PDA agar by using tartaric acid, decrease the pH values to 3.5 that inhibit most of the growth food spoilage and food poisoning bacteria. PDA agar contained rich potato infusion that promotes the growth of yeast and molds. DRBC agar is a selective media that commonly used for enumeration of yeasts and molds. Inhibition of bacteria and yeasts can be achieved by adding dichloran into the RBC agar which lowered the pH to 5.6. It also controls the rapid spreading of mucoraceous fungi and limits the colony sizes of other genera. YMA agar was the media that aids to isolate and maintain the yeasts and molds in the food sample. By acidified the agar, the pH will drop to 4 lead to inhibition of
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