Question

1. Which plate(s) showed an unexpected result in the above experiment?

2. Provide the most likely explanation for the unexpected results.

Table 2: Hypothetical results from transformation experiments performed in a pGLO plasmid added to cells? No No Type of agar plate Total # colonies # Green colonies under UV light LB LB + ampicillin LB + ampicillin LB + ampicillin+ arabinose 100 es

Answer 1

According to me, the first row result should be an unexpected result.

Trepeta and Edberg modified MacConkey Agar by the incorporation of 4-methylumbelliferyl-beta-D-glucuronide (MUG); the resulting medium allowed the authors to presumptively identify Escherichia coli from the primary plating medium within five minutes. The above reaction is possible because most strains of E. coli (96-97%) produce glucuronidase, an enzyme that hydrolyzes MUG to 4-methylumbelliferone. This compound fluoresces under long-wave ultraviolet light (366nm). The addition of MUG to the formulation allows beta-glucuronidase positive strains ofE. coli to fluoresce blue-green when examined under this wavelength of UV light.