Electrochemical biosensor array for the identification of microorganisms based on lectin-lipopolysaccharide recognition

Rapid identification of bacterial strains remains a well-known problem in a pplied medicine and, for viable pathogens, is an important diagnostic goal. We have investigated an electrochemical biosensor array, in which transduc tion is based on respiratory cycle activity measurements, where the microor ganism's native respiratory chain is interrupted with non-native external o xidants. The selective biochemical recognition agents employed in this stud y are lectins that, once immobilized, recognize and bind to cell surface li popolysaccharides. Porous membranes with different surface properties were examined as potential immobilization supports for these lectins. Optimizati ons performed using concanavalin A and E. coli JM105 show that immobilizati on methods involving preactivated membranes significantly reduce the time r equired to create a functional lectin layer on the membrane surface. Overal l, we found general agreement between agglutination test results and the el ectrochemical assessment of lectin-cell binding. Chronocoulometric measurem ents were made for cells captured on lectin-modified Immunodyne ABC membran es physically affixed to Pt working electrodes. This lectin-based sensor ar ray was exposed to viable cells of Grain-negative and Grain-positive bacter ia as well as yeast, and chronocoulometric. measurements were used to gener ate a pattern of responses for each organism toward each lectin. Principal component analysis was used to classify the chronocoulometric results for t he different microbial strains. With this new method, six microbial species (Baccilus cereus, Staphylococcus aureus, Proteus vulgaris, Escherichia col i, Enterobacter aerogenes, Saccharomyces cerevisiae) were readily distingui shed.