Rapid Detection of Listeria monocytogenes in Milk by Surface Plasmon Resonance Using Wheat Germ Agglutinin

Abstract

The current study made an attempt to develop a novel surface plasmon resonance (SPR) sensor using wheat germ agglutinin as a biomolecule for the rapid detection of Listeria monocytogenes. A selective biomolecular interaction of wheat germ agglutinin (WGA) lectin with surface carbohydrate components of L. monocytogenes was used as a biorecognition principle. From the previous studies based on agglutination and sugar inhibition principle, we have selected WGA as a highly selective ligand for L. monocytogenes-WGA biomolecular interaction study using a SPR (Biacore 3000) sensor. Under optimized assay conditions, L. monocytogenes strains have generated maximum response of 479 ± 49 resonance unit (RU) at 7.4 log cfu/100 μl with a least cross-reactivity in presence of both G+ve and G−ve Bacterial contaminants. The limit of detection of 3.25 log CFU/100 μl was obtained for the detection of L. monocytogenes by lectin immobilized WGA CM5 chip surface using SPR. Further, the WGA-immobilized chip was evaluated with milk samples enriched in Listeria selective enrichment medium and the response (RU) was again found to be significant up to 3.0 log CFU/100 μl.