|Description:||This image depicts two test tubes. The tube at left contained triple sugar iron (TSI) growth medium on a slant, and the tube at right contained O/F glucose medium. Each tube had been inoculated with a microorganism that was classified as being non-oxidative, and non-fermentative, which is evidenced through the lack of any color change in the O/F glucose medium (Rt), nor the TSI medium tube (Lt).|
The lack of color change in the O/F glucose medium (Lt), identified the organism as one that neither oxidizes nor ferments glucose, for in each case the medium would have been turned acidic, thereby, changing the medium to a yellow coloration. Had oxidation or fermentation occurred in the TSI tube (Lt), a color change to yellow, either in the butt alone, or throughout the tube, i.e., depending upon which sugars were metabolized, would have occurred.