C. Interpretation of results
1. Fermentative results
Bacteria that can ferment glucose give a fermentative result as indicated by acid production in both the open (aerobic) and oil covered (anaerobic) tube. The acid produced (pH 6.0) changes the pH indicator, bromthymol blue, from green to yellow. The semisolid consistency of the medium also allows for detection of motility. Note hazy growth away from the stab line (Fig. 1) (8).