Enrichment and rapid detection of Bacillus anthracis spores by direct im-munofluorescence assay

A direct immunofluorescence assay for detection of Bacillus anthracis spores was developed. B. anthracis spores were spiked in water, sand and talcum powder and recovered by aqueous polymer bi-phasic buffer system. Maximum spores could be recovered from tap water followed by sand and talcum powder. Subsequently, a direct immunofluorescence assay for detection of recovered spores was developed using polyclonal antibodies raised against formalin-inactivated spores. The fluorescein-conjugate was absorbed with spores of other bacteria to remove cross reactivity. The assay could detect 3.6 x 10³ spores mL⁻¹ from tap water and 3.6 x 10⁴ spores g⁻¹ from sand and talcum powder. The proposed method can be employed in environmental surveillance of B. anthracis.