Detection of Bacillus anthracis DNA in complex soil and air samples using next-generation sequencing [NimbleGen Array data]

One of the cornerstones of an effective biodefense strategy is the ability to detect infectious agents with a high degree of sensitivity and specificity in the context of a complex sample background. The nature of the B. anthracis genome, however, renders specific detection difficult, due to close homology with B. cereus and B. thuringiensis. We therefore elected to determine the efficacy of next-generation sequencing analysis and microarrays for detection of B. anthracis in an environmental background. We applied next-generation sequencing to titrated genome copy numbers of B. anthracis in the presence of background nucleic acid extracted from aerosol and soil samples. We found next-generation sequencing to be capable of detecting as few as 10 genomic equivalents of B. anthracis DNA per nanogram of background nucleic acid. Detection was accomplished by mapping reads to either a defined subset of reference genomes or to the full GenBank database. Moreover, sequence data obtained from B. anthracis could be reliably distinguished from sequence data mapping to either B. cereus or B. thuringiensis. We also demonstrated the efficacy of a microbial census microarray in detecting B. anthracis in the same samples, representing a cost-effective and high-throughput approach, complementary to next-generation sequencing. This Series contains the NimbleGen array data only (no next-generation sequencing data). The next-gen sequencing data from this study are accessible in the BioProject database under accession PRJNA206989. B. anthracis DNA was spiked at 6 different concentrations (1, 10, 100, 1000, 10000 and 100000 genome copies) into 1 ng of background nucleic acids extracted either from a soil sample or from an aerosol (air filter) sample. Two replicates of each combination of B. anthracis copy number and background sample were analyzed.