DEVELOPMENT OF A SENSITIVE AND QUANTITATIVE ENZYME-LINKED IMMUNOFILTER ASSAY (ELIFA) FOR WHOLE BACTERIAL-CELLS

The application of enzyme-linked immunofilter assay (ELIFA) techniques to the detection of whole bacterial cells in aqueous samples is descr ibed. In a qualitative assay, Escherichia coli cells were collected on 25 mm diameter cellulose ester membranes in filter holders and treate d in situ with rabbit anti-E. coli IgG, phosphatase-conjugated anti-ra bbit IgG and chromogenic enzyme substrate. The presence of 10(4) bacte ria per membrane was detected by colour development (assessed visually ) in a total time of 2 h 15 min. In,a modification of the procedure, m embrane-bottomed plates containing 96 x 6 mm diameter wells were used and after application of the enzyme substrate the membrane from each p late was peeled off and scanned at 626 nm. This procedure enabled the quantitative detection of 10(3) to 10(7) bacteria per membrane in a ti me of 1 h 45 min.