BIO250 Lab 4 Selective Media & Agar SPRING 2024

Lab Report Format Expectations Utilize college level grammar and professional formatting when completing this worksheet. Submissions without proper formatting, all required photos or sufficient responses will be rejected. Pre-lab Questions 1. In this lab, you will conduct three different experiments that each cover the topic of selective media and agar. How are these experiments different from one another? Explain how the different media in each experiment are utilized in the context of selective vs differential media. The experiments vary in their objectives and media utilization. In Experiment 1, starch agar is employed to select starch-digesting bacteria. Experiment 2 involves the isolation of Staphylococcus aureus using mannitol salt agar. Experiment 3 entails screening for coliforms in water, utilizing MacConkey agar. 2. What is the difference between chemically defined and chemically complex media? Give an example (a clinical or environmental research application) of when you would use each type of medium to culture different microorganisms. The distinction between chemically defined and chemically complex media lies in their compositions. Chemically defined media consist of precisely known compositions, such as glucose broth. On the other hand, chemically complex media have unknown compositions that can vary from batch to batch, like nutrient broth. 3. Why do we grow microorganisms on general growth media first, before inoculating differential media? Cultivating microorganisms on general growth media facilitates the initial isolation and selection of particular species. Subsequently, these isolated cultures can be transferred to differential media to observe specific metabolic characteristics or reactions. This process aids in the identification and differentiation of microbial species based on their distinctive traits. 4. What changes might you see on a differential plate that helps identify the bacteria? Changes in colony color, size, or other visible traits on a differential plate can serve as indicators