A DNA microarray facilitates the diagnosis of Bacillus anthracis in environmental samples

Aims: In order to improve the diagnosis of Bacillus anthracis in environmental samples, we established a DNA microarray based on the ArrayTube technology of Clondiag. Methods and Results: Total DNA of a bacterial colony is randomly biotinylated and hybridized to the array. The probes on the array target the virulence genes, the genomic marker gene rpoB, as well as the selective 16S rDNA sequence regions of B. anthracis, of the Bacillus cereus group and of Bacillus subtilis. Eight B. anthracis reference strains were tested and correctly identified. Among the analysed environmental Bacillus isolates, no virulent B. anthracis strain was detected. Conclusions: This array clearly differentiates B. anthracis from members of the B. cereus group and other Bacillus species in environmental samples by chromosomal (rpoB) and plasmid markers. Additionally, recognition of B. cereus strains harbouring the toxin genes or atypical B. anthracis strains that have lost the virulence plasmids is feasible. Significance and Impact of the Study: The array is applicable to the complex diagnostics for B. anthracis detection in environmental samples. Because of low costs, high security and easy handling, the microarray is applicable to routine diagnostics.