Rapid, Sensitive, and Selective Quantification of Bacillus cereus Spores Using xMAP Technology

Bacillus cereus is a spore-forming ubiquitous bacterium notable as a food poisoning agent. Detection of B. cereus spores using selective media is laborious and non-specific. Herein, the quantitative detection of B. cereus spores was investigated with commercial antibodies and published aptamer sequences. Several detection reagents were screened for affinity to Bacillus collagen-like protein A (BclA), an abundant exosporium glycoprotein. Sensitivity and selectivity toward B. cereus spores were tested using immunoassays and multi-analyte profiling (xMAP). A recombinant antibody developed in llama against BclA protein showed B. cereus spore selectivity and sensitivity between 102 and 105 spores/mL using xMAP. DNA aptamer sequences demonstrated sensitivity from 103 to 107 spores/mL and no cross-reaction to B. megaterium and B. subtilis. Selectivity for B. cereus spores was also demonstrated in a mixture of several diverse microorganisms and within a food sample with no compromise of sensitivity. As proof of concept for multiplexed measurement of human pathogens, B. cereus and three other microorganisms, E. coli, P. aeruginosa, and S. cerevisiae, were simultaneously detected using xMAP. These data support the development of a rapid, sensitive, and selective system for quantitation of B. cereus spores and multiplexed monitoring of human pathogens in complex matrices.