Explain Alkaline Butt -carbohydrate utilization pattern test?

Alkaline slant (red) and alkaline butt (red) or no change (orange-red) butt- Instead of carbohydrates, peptone in the medium produces ammonia on fermentation, resulting in alkaline pH. Fermentation occurs either aerobically (alkaline reaction is produced only in slant) or anaerobically (alkaline reaction is present on the slant and the butt).

Along with carbohydrate fermentation, tubes should also be examined for the presence or absence of black colouration along with the line of stab inoculation. Growth of some common bacteria on TSI medium is given in the Table. We shall use this information for identification of bacteria.