Some bacteria ferment certain carbohydrates, while producing acidic or gaseous products; this information can be utilized in order to identify bacteria (Morello and Granato, 2003). In order to test for carbohydrate fermentation, tubed broths, containing a Durham tube for trapping any gas formed when the broth is incubated, are utilized (Morello and Granato, 2003). After incubation, a color change indicates that an acid product was formed, and a bubble in the Durham tube indicates that a gas was formed. In this study, carbohydrate fermentation tests for the presence of glucose, maltose, lactose, and sucrose in Proteus Vulgaris were performed. The results were then compared to the results of prior experiments.
Materials and Methods:
Four tubed broths (Glucose, Maltose, Lactose, and Sucrose) are obtained. The tubes were inoculated with Proteus Vulgaris, and were incubated for 24 hours at 35°C. After incubation, tubes were examined for change of color to yellow and the formation of a bubble in the Durham tubes.
A = Acid Production
G = Gas Formation
NA = Neutral (no change in color)
| Glucose| Maltose| Lactose| Sucrose|
Proteus Vulgaris| A/G| NA| NA| A/G|
Results of prior carbohydrate fermentation tests
In our results, an acid and a gas were both produced in the glucose and sucrose tubes; however, no gas or acid was produced in the maltose and lactose tubes. According to the chart above, our results are identical to the results of prior carbohydrate fermentation tests on Proteus Vulgaris. Thus, we can conclude that Proteus Vulgaris ferments both glucose and sucrose, in which both an acid and a gas are produce, but does not ferment maltose or lactose.
Morello, J, Mizer, H. and Granato, P. (2003) Lab Manual and Workbook in Microbiology (7th Ed) New York:McGraw-Hill.