ANYL 156 |
| A fluorescence-based assay was developed to detect viable Escherichia coli in water. The assay uses following principle: biotin-labeled capture antibodies (Ab) was immobilized on paramagnetic microbeads (2.8 mm diameter) that have been functionalized with streptavidin (bead-Ab). The bead-Ab conjugate captured E.coli from water solution. The captured E.coli was incubated in tryptic soy broth (TSB) with the added isopropyl b-galactopyranosidase (IPTG) to induce production of b-galactosidase in the bacteria. The bacteria lysis was done to release enzyme, which was used to convert substrate 4-methylumbelliferyl-b-D-galactoside (MUG) into fluorescent product. The advantage of method is detection of only live bacteria, because many immunoassay-based methods don't distinguish between live and dead bacteria. Bacteria viability after capture with the paramagnetic beads was investigated with the epifluorescence microscope. Bacteria was exposed to two dyes simultaneously SYTO 9 (green-fluorescent nucleic acid stain; Invitrogen) and propidium iodide (red-fluorescent nucleic acid stain), bacteria with intact cell membranes stain fluorescent green, whereas bacteria with damaged membranes stain fluorescent red. |
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General Papers
7:00 PM-9:00 PM, Sunday, 10 September 2006 Moscone Center -- Hall D, Poster
Sci-Mix
Division of Analytical Chemistry |