Hydrodistillation and antimicrobial properties of lemongrass oil (Cymbopogon citratus, Stapf): An undergraduate laboratory exercise bridging chemistry and microbiology

A traditional classroom usually focuses on concepts from a specific discipline. However, solving complex real-world problems requires integration and application of knowledge from various fields. Here, we describe a 4-hr undergraduate-level laboratory exercise that utilizes concepts of extraction and biological property, bridging between chemistry and microbiology courses. In the first half of this exercise, students performed hydrodistillation to extract essential oil from a locally available herb, lemongrass (Cymbopogon citratus, Stapf). In the second half, students investigated the potential antimicrobial activity of the extracted oil against various microorganisms using the Kirby–Bauer disk diffusion method. Students also developed their own experimental questions based on the extracted oil and the antimicrobial testing technique. Self-assessment questionnaire shows students’ appreciation of the experiments and substantial learning gains in the extraction process, properties of the extracts, and antimicrobial activity testing. This laboratory exercise prompts students to formulate their own experimental questions and engages students in interdisciplinary experimentation.