For this exercise, we use the GasPak anaerobic system by Becton Dickinson. This system consists of a polycarbonate jar, a lid with a gasket to prevent air flow, a strip infused with methylene blue, and a pouch containing sodium borohydride, sodium bicarbonate, citric acid, and a palladium catalyst.
When water is added to the pouch, the sodium borohydride, sodium bicarbonate, and citric acid react to form hydrogen and carbon dioxide. The palladium catalyzes a reaction between the hydrogen and the oxygen within the jar; this reaction creates water, which forms as condensation on the inside of the jar. Methylene blue is blue in the presence of oxygen but is colorless in an anaerobic environment. When the oxygen is converted to water and condensation forms on the side of the jar, the indicator strip will turn from blue to white.
You will spot streak nutrient agar or Brewer's anaerobic agar plates with several organisms, and then you will place your plates in the anaerobic jar. You instructor will start the reaction and seal the jar. The entire jar will then be incubated at 37°C. Anaerobes should grow while obligate aerobes should not. Will microaerophiles grow?