Lab 2: Aseptic Technique, Media Preparation & Microbial Growth Curve Determination
Description
This interactive virtual lab places students in the role of a lab technician isolating and culturing an environmental bacterial isolate from start to finish, from donning proper PPE and sterilizing an inoculating loop, through preparing and autoclaving agar media, pouring and streak-plating cultures, performing serial dilutions with a virtual micropipette, and finally reading optical density on a spectrophotometer to construct a live bacterial growth curve. A final station contrasts aerobic and anaerobic incubation side by side, letting students see firsthand how oxygen availability shapes microbial growth. Every station requires completing a hands-on drag-and-drop or simulated activity before advancing, with each step automatically logged to a lab notebook so students build a complete record of the procedure as they go.
Learning Outcomes
By completing this lab, students will be able to correctly sequence and justify the steps of aseptic technique, including PPE use and loop sterilization, to prevent culture contamination. They will be able to describe proper media preparation and autoclave sterilization conditions (121°C, 15 psi) and explain why sterility is essential before inoculation. Students will be able to perform and interpret the purpose of streak-plating for colony isolation and serial dilution for obtaining countable, measurable cell densities. They will be able to explain what OD₆₀₀ measures and use spectrophotometric readings to construct and interpret a bacterial growth curve, correctly identifying the lag, exponential, stationary, and death phases in relation to Monod growth kinetics. Finally, students will be able to distinguish aerobic respiration, anaerobic respiration, and fermentation by their electron acceptors and relative ATP yields, and explain how oxygen availability determines which environmental microorganisms thrive under a given set of incubation conditions.