Table 1.

Methods for detection of Bacillus spores.

Method	Sensitivity	Organisms	Comments	References
NUCLEIC ACID BASED METHODS
Real-time PCR	1 spore per 100 L of air	B. anthracis		Lee et al., 1999; Makino and Cheun, 2003; Irenge et al., 2010; Wielinga et al., 2011
Culture-based PCR	1–10 spores per analysis	B. anthracis	High-throughput	Kane et al., 2009
NASBAa coupled with biosensor	1–10 spores per analysis	B. anthracis	Analysis after 30 min of germination	Baeumner et al., 2004
FISHb	103 spores per m3 of air	B. anthracis		Weerasekara et al., 2013
ICANc DNA detection	104 spores per analysis	B. subtilis	Does not contain a germination step	Inami et al., 2009
Autonomous pathogen detection system with multiplexed PCR		B. anthracis and others		Regan et al., 2008
RAZOR® EX Anthrax Air Detection System	200 spores per analysis	B. anthracis	DNA extraction and real-time PCR	Spaulding et al., 2012; Hadfield et al., 2013
IMMUNOASSAYS
Colorimetric and electrochemilumine-scence immunoassay	30–100 spores per analysis	B. anthracis		Morel et al., 2012
ELISAd		B. subtilis		Zhou et al., 2002
On-chip ELISA	105 spores per analysis	B. subtilis	Chemiluminescence method combined with a biochip. Antibodies against surface spore antigen were used	Stratis-Cullum et al., 2003
Luminex assay	103–104 spores per ml	B. anthracis	Monoclonal antibodies recog-nize anthrose-containing oligosaccharides on the surface of B. anthracis endospores	Tamborrini et al., 2010
Peptide-Function cantilever arrays	105 spores per ml for analysis	B. subtilis	1 from 2400 spores was captured	Dhayal et al., 2006; Campbell and Mutharasan, 2007
Chip gel electrophoresis protein profiling (CGE-PP)	16 particles per liter 100 cells per analysis	Any (adapted for E. coli and B. subtilis)	Autonomous microfluidic system	Pizarro et al., 2007; Stachowiak et al., 2007
Multiplexed Immunoassay with PCR Confirmation	49 spores per liter of air	B. subtilis	Autonomous Detection of Aerosolized Biological Agents	McBride et al., 2003; Hindson et al., 2004
OTHERS
Pyrolysis micromachined differential mobility spectrometry	103 spores per analysis	B. anthracis	A microfabricated ion mobility spectrometer in combination with a pattern recognition and classification algorithm	Krebs et al., 2006
Microcalorimetric spectroscopy	100–1000 spores	B. subtilis, B. cereus		Arakawa et al., 2003
Laser induced breakdown spectroscopy	single particles	B. subtilis	In combination with other detection methods	Hybl et al., 2003, 2006
Mass-spectrometry	104–105 spores	B. anthracis	In combination with other detection methods	Lasch et al., 2009; Chenau et al., 2011; Li et al., 2012
Raman scattering	104 spores	Not specific	Based on detection of dipicolinic acid	Cheng et al., 2011, 2012; Cowcher et al., 2013
Optical microchip array biosensor	5 × 107 spores per ml	B. anthracis and others		Bhatta et al., 2011

^aNASBA, Nucleic acid sequence based amplification.

^bFISH, Fluorescence in situ hybridization.

^cICAN, Isothermal and chimeric primer-initiated amplification of nucleic acids.

^dELISA, Enzyme linked immunosorbent assay.