Modified spot hybridization test using biotinylated DNA probe.

A modification that simplifies the spot hybridization technique is described for using biotinylated DNA probes. Plasmid EWD299 having LT gene insert, labelled with biotin either by nick translation or using photobiotin was used as DNA probe for the specific detection of enterotoxigenic Escherichia coli. A simple protocol has been described for easy lysis of test samples by boiling in distilled water followed by detergent treatment and was found to be as efficient as the lysis using lysozyme and protease. Three different solid supports namely DEAE-cellulose paper, nitrocellulose paper and nylon membrane were also compared for their suitability in this spot hybridization test. Nitrocellulose paper was found to give better colour signal with the photobiotinylated DNA probe.