Living cells of E. coli can be reliably detected with media that contain a chromogenic or fluorogenic substrate for beta-glucuronidase (also termed β-D-glucuronidase), an enzyme that occurs almost exclusively in E. coli.
The novel patented substrate RUG® (Resorufin-beta-D-glucuronicacid methyl ester, Cat. No. R-2155_P00) is transfered by E. coli into the very robust and bright dye Resorufin. Resorufin is one of the most intensely fluorescent materials known today. Hence Resorufin-beta-D-glucuronide represents the perfect agent to detect E. coli bacteria at very low concentrations. Until recently, the application of this reagent was limited by low availability and high costs.
At Biosynth’s microbiology lab we discovered that the methyl ester analog Resorufin-beta-D-glucuronidemethyl ester (RUG®) performs exactly the same as the free acid reagent Resorufin-beta-D-glucuronide.
Assay: Escherichia coli ATTC 25922 was inoculated at low density (20 CFU / mL) in an E. coli detection broth containing RUG® (Cat.No. 2155_P00). The tubes were incubated at 37°C and 150rpm.
Today, 4-Methylumbelliferyl beta-D-glucuronide (MUG) (Cat. No. M-5700) is commonly used as a substrate for detecting beta-glucuronidase activity in food, drinking water, clinical samples and for rapid bacterial identification in blood cultures.
In contrast to MUG, RUG® does not require fluorescent detection, as the released dye Resorufin is itself of intense pink color. But of course, fluorescent detection is an option:The strong fluorescence of Resorufin is excited at 565 nm in the range of red light and does not require UV illumination, instead it's already visible at daylight.
Another exciting fact about RUG® for users is that the product is chemically stable and can resist even prolonged storage at temperatures above RT (more than 4 months at 37°C). As a consequence, prepared media containing RUG® as a substrate may be stored at ambient temperatures at warm climate conditions.
RUG® is economic
Using RUG® instead of MUG is an economic decision even though there are higher costsof purchase for the top-notch substrate RUG®:
+ Low concentration of substrate
+ Short incubation times
+ No UV light required for detection
+ High storage stability
+ No additional antibiotic is required in the growth media
For more information and to order online please visit the RUG® product page