SIMPLE, SENSITIVE ASSAY FOR MICROBIAL AMINOPEPTIDASE

A fluorimetric assay has been developed using several aminoacyl-7-amid o-4-methyl coumarin (AMC) substrates (L-leucine-, L-alanine-, L-argini ne-, L-tyrosine-, L-phenylalanine-, L-serine- and L-valine-AMC) in bla ck multi-well plates to measure microbial aminopeptidase activity in l actobacilli intact cell suspensions (10(9)-10(10) CFU/mL). The fluores cence emission was visually evaluated by panelists and showed that sub strate concentrations of 0.01 mM were optimal for visual detection and thus useful for rapid screening of many strains. The different ratios of activities quantitated in a multiscan fluorimeter showed a potenti al for differentiation among strains.