Changes in the luminescence between dried and wet bacillus spores

Abstract

Fluorescence has been suggested as a method with which to detect and identify bacterial spores. To better understand the nature of the fluorescence signal, we observed the intrinsic steady-state fluorescence and phosphorescence spectra of Bacillus globigii (BG) in both dried and aqueous forms. In vitro, dried, and suspension forms of BG were measured at room temperature in 300-600-nm excitation wavelengths. Also, the phosphorescence of dry BG spores was measured at room temperature at 300-600-nm excitation wavelengths. The wet BG spores exhibited a strong maximum in their fluorescence spectrum, with the peak excitation wavelength near 300 nm and emission wavelength near 400 nm. When the BG was dried, this peak shifted to an approximately 450-nm excitation maximum and an 500-nm emission maximum. The difference between the wet and the dry spore fluorescence spectra cannot be explained by the phosphorescence of the dry spores. Other changes must take place when the spores are wet to account for the large changes observed in the spectrum.

Combined use of Mie–Raman and fluorescence lidar observations for improving aerosol characterization: feasibility experiment

“…It should just be mentioned that, in principle, the water environment may affect the fluorescence efficiency. For example, the fluorescence cross section of wet bacterial spores is higher than that of dry ones (Kunnil et al, 2004). For insoluble particles, the presence of a water shell can also lead to an additional increase of the fluorescence due to the lens effect produced by the droplet.…”

Combined use of Mie-Raman and fluorescence lidar observations for improving aerosol characterization: feasibility experiment

“…The fluorescence cross section of particles may be subject to hygroscopic effect so impacted by the amount of available water vapor (RH). For example, it is known, that fluorescence cross section of wet bacterial spores is higher than that of dry ones (Kunnil et al, 2004). For insoluble particles, the presence of a water shell can lead also to additional increase of the fluorescence, due to the lens effect produced by the droplet.…”

One-step conversion of dipicolinic acid to its dimethyl ester using monomethyl sulfate salts for GC-MS detection of bacterial endospores

“…Reagent-less autofluorescence of spores 15 N/A a Direct UV absorbance of spores [16][17][18][19] 5 Â 10 6 spores mL À1…”

“…14 Reagent-less autofluorescence of spore samples has been investigated since CaDPA exhibits some fluorescence. 15 Direct UV absorbance, although less sensitive than fluorescence, requires no DPA-complexing reagent to function. [16][17][18] The lowest detection limit reported for this method is approximately 5 Â 10 6 spores mL À1 .…”