Bacterial Endospore Detection Using Terbium Dipicolinate Photoluminescence in the Presence of Chemical and Biological Materials

Abstract

A determination of the viability of an endospore detection technique using terbium dipicolinate photoluminescence in the presence of other chemical and biological materials was performed. The compounds and organisms examined, possible environmental constituents, covered three broad categories: organic compounds, inorganic compounds, and biological materials. Each substance was tested for a false positive, which occurs if the intrinsic terbium photoluminescence is enhanced in the absence of a bacterial endospore. The detection technique was also investigated for false negatives, which occur if a known positive endospore signal is inhibited significantly. Although several materials may give rise to false negative signals, none caused a false positive signal to be observed.

Interaction of dipicolinic acid with water-soluble and immobilized porphyrins

“…Recent threats of contamination in the United States and the continuing danger to military personnel and civilians alike indicate the need for a detector of biological agents that operates in real time and that can function in a variety of environments. Several methods for detection of bacterial spores have been developed including PCR [2,3], immunofiltration assay [4,5], polymorphism analysis [6], direct detection of DNA sequences [7], liquid chromatography [8], FT-IR [9] and those which indicate bacterial spore presence by detection of DPA [10][11][12][13][14][15][16][17][18][19][20].…”

“…One method currently employed for detection of DPA is to measure the increase in terbium fluorescence when it binds DPA [15,17,18,20]. In this method, solutions of DPA or bacterial spores are mixed with terbium solutions followed by separation of insoluble materials.…”

“…Emission and excitation spectra are recorded from 450 to 640 and 270 to 280 nm, respectively. The Tb fluorescence intensity increases without a wavelength shift in the emission spectrum [14,15,17,18,20]. However, phosphate-containing compounds quench the fluorescence of the Tb-DPA complex [18]; this problem can be solved by adding AlCl 3 to the solution prior to separation of insoluble particles [20] to remove phosphate from solution.…”

Amyloid Histology Stain for Rapid Bacterial Endospore Imaging

“…For the last decade, dipicolinic acid (DPA) has gained considerable popularity as a marker for the detection of bacterial endospores (16,22,25,59,67,83,92,97). Emission enhance-ment assays for DPA and bacterial endospores, utilizing lanthanide ions, were developed at the U.S. Army Research Laboratory at the end of the 20th century (59,67) and were recently improved by a research team at the Jet Propulsion Laboratory (9,10).…”

“…Emission enhance-ment assays for DPA and bacterial endospores, utilizing lanthanide ions, were developed at the U.S. Army Research Laboratory at the end of the 20th century (59,67) and were recently improved by a research team at the Jet Propulsion Laboratory (9,10). Up to about 20% of the weight of bacterial endospores can be attributed to calcium dipicolinate: i.e., DPA is a natural product observed solely in sporulated bacterial species (75,76).…”