Simple Bacterial Stain Lab

Greetings! Microbiology is my favorite unit to teach in biology. It’s no surprise that microbiology was my favorite science college course. I wrote this user-friendly and safe version of this simple stain lab for bacteria, because my middle school students needed it. They love hands-on lab experiences, and I love to offer them those learning opportunities. I want them to have a successful lab experience and to grow confidence in their safe application of their laboratory skills.

I have also facilitated this lab in high school biology. This lab is a prepares students for the Gram stain structural stain lab, which usually follows this lab in the series, because the first six procedural steps are the same.

Bacterial cells are colorless as are human cells. Scientists typically heat fix and stain bacteria to view them through a compound light microscope.

The student lab manual sheet is a full page in length. It includes the following sections – background, lab safety, purpose, and the directions (procedure). I do not offer analysis questions with this activity. It is the students’ mission to safely perform the lab, and to call the instructor over to verify their view of the stained bacteria under a 40x objective lens. Once the instructor writes his or her initials on the designated line, students are ready to sketch their view of the bacteria in the appropriate box.

Materials needed, but not included with this listing, are the following – an incubated bacterial culture(s) (either from a swab collection lab activity the prior day or from a culture ordered from a supply company), metal or disposable inoculating transfer loops, Bunsen burners, strikers, methylene blue stain, lab safety goggles, lab aprons, stain-holding containers, transfer pipettes or medicine droppers, wash bottles for water transfer, Kimwipes, compound light microscopes with a light source, and cases of glass slides.

This document is in a PDF file. It will become editable upon conversion to Microsoft Word using an Adobe Acrobat Reader DC app. My directions cover both major ways of bacterial source and transfer. The directions stress lab safety with precautions working with bacteria, Bunsen burner flames, and with a stain that is permanent once it sets on clothes.

I also provided a one-page teacher’s lab manual. It offers tips I have learned from facilitating this lab for over twenty years. It includes a listing of common errors students make when using a compound light microscope.

There is no answer key with this activity.

This resource complements the following lessons in my store.

Bacteria Homework Quiz

Bacteria Classification by Mode of Nutrition and Gas Exchange Worksheet

Classification of Bacteria Concept Map/Graphic Organizer

Microbiology Unit Review Packet

Protist, Fungi, Bacteria and Virus Tournament Bracket Challenge

Bacteria Shape and Colony Naming and Drawing Worksheet

Microbiology Gram Stain Lab

I appreciate your interest. I have successfully published games, books, and lab kits through a myriad of international science supply corporations dating back to 2002. Order with confidence!