Rapid FRET based anthrax diagnosis

The invention comprises a substrate for detection of micro-organisms, wherein said substrate comprises a set of molecular markers linked to a di, tri- or tetrapeptide consisting of amino acids X1 and X2, X1, X2 and X3 or X1, X2, X3 and X4, respectively, in which one of them, for example X1 is a D-amino acid and the others, for example X2, X3 and X4 may be any D- or L-amino acid. Said substrate preferably is used for the detection of Bacillus anthracis and preferably a set of molecular markers linked to a dipeptide or tripeptide consisting of two amino acids X1 and X2 or three amino acids X1, X2 and X3. respectively, in which either - one of X1, X2 and X3 is DLeu and one of the others is any L- or D-amino acid, preferably Leu, or - one of X1, X2 and X3 is a D-amino acid and one of the others is preferably Leu. The invention further comprises methods for detection of micro-organisms, specifically Bacillus anthracis , with the substrates of the invention. The preferred substrates are, for example, Ac-NH-Cys(S-Ac)-Leu-(D)Leu-Cys(S-Ac)-OH and FITC-Ahx-(D)Leu-Leu-Lys-DABCYL