primers to amplify the anthrax specific dna fragments in sludge samples spiked with anthrax dna spiked samples were prepared using 0 001 0 01 0 1 or 1 ng of anthrax dna with 50 ng sludge dna these amplification assays were set up in an attempt to determine the detection limit of anthrax dna in the presence of an overwhelming amount of non specific background dna typically in rapd assays low stringency annealing conditions are used to allow priming event even if the primers are not fully complementary to the priming sites i e a certain level of mis match is allowed in an effort to determine which primers are more specific to the priming sites an annealing temperature of 52 u00b0 c was used to preclude priming events from mismatched sites as shown in fig5 primer nos 173 and 280 were able to amplify at high stringency temperature even in the presence of 0 001 ng 1 pg control anthrax dna this result indicates that the pcr assay is highly sensitive for detection of anthrax dna even in the presence of 5 000 fold excess of non specific dna assuming 0 28 pg dry wt bacterial cell and 3 of the dry wt to be dna cited in neidhardt fc ed in escherichia coli and salmonella cellular and molecular biology asm press 1996 the ability of a pcr based technology to detect the presence of 1 pg dna suggests that this technology would detect dna from as many or as few as 120 150 b anthracis cells while it is a most desirable objective of the invention to be able to detect the presence of even fewer preferably 1 10 anthrax cells no other.