MicroID Lab Guide: an open-source, customizable web application to guide students through unknown bacterial identification in undergraduate microbiology labs.

Identifying an unknown bacterial isolate is a core exercise in many undergraduate microbiology courses, but students often struggle to organize observations, select appropriate follow-up tests, and interpret results in a logical sequence. To support this process, I developed the MicroID Lab Guide, a free, open-source progressive web application that guides students through a four-phase bacterial identification workflow. The application supports initial observations, automated routing through an identification flowchart, biochemical test selection and interpretation, and final organism identification with an automated confidence check. As students enter results, a rule-based decision engine updates the list of candidate organisms and flags inconsistencies between observed and expected results. The tool also includes a searchable reference library of 67 laboratory techniques, media, and biochemical tests to provide students with on-demand procedural and interpretive support. MicroID Lab Guide runs entirely in the browser; requires no server, user accounts, or data collection; and can be used as a static web application. Importantly, the application was designed for instructor customization: organism profiles, biochemical test definitions, flowchart logic, and export templates are stored in editable source files. This article describes the design, classroom use, customization, and AI-assisted development of MicroID Lab Guide as a flexible, zero-cost model for building course-specific digital tools in undergraduate microbiology laboratories.