Investigation: Bacteria


This investigation asks students to take samples from the school and grow bacteria on agar plates.  Students learn to use sterile technique to transfer and stain the bacteria and view under a microscope.  

Lab guide includes instructions for how to analyze and compare colonies and identify the three shapes of bacteria:  bacillus, cocci, and spiral.  

Samples of known bacteria, such as E. coli and Bacillus subtilis can also be ordered to include an optional gram stain.  Prepared slides can also be viewed instead of cultured bacteria to compare bacteria shapes.

The investigation does require basic laboratory supplies to complete, such as microscopes, innoculating loops, and alcohol burners (or bunsen burners) and is intended for an AP biology class.  

The investigation is open-ended and asks students to eventually create a report or info-graphic that provides evidence that the lab goals have been achieved.  Students are encouraged to take photos of the processes as they complete the lab.

Grade Level:  11-12
Time Required:  2-3 lab periods,  2-3 days for incubation*

If you do not have an incubator, you can improvise by using a reptile heat lamp placed over an aquarium.  Samples will grow over a weekend if the heat is kept between 80-90 degrees.