The invention comprises a substrate for detection of micro-organisms, wherein said substrate comprises a set of molecular markers linked, optionally with
linker molecules or moeieties, to a di-, or
tripeptide consisting of amino acids X1 and X2, or X1, X2 and X3, in which one of them, for example X1, is a D-
amino acid and the others, for example X2 and X3, may be any D- or L-
amino acid. Said substrate preferably is used for the detection of
Bacillus anthracis. Alternatively, the invention is directed to a substrate for detection of micro-organisms, more specifically P. aeruginosa, wherein said substrate comprises a set of molecular markers linked, optionally with
linker molecules or moeities to a tri-
tetra or pentapeptide consisting of
glycine amino acids. The invention further comprises methods for detection of micro-organisms, specifically
Bacillus anthracis and
Pseudomonas aeruginosa, with the substrates of the invention and use of the substrate(s) in such a method.