<title>Fluorescence of dipicolinic acid as a possible component of the observed UV emission spectra of bacterial spores</title>

Abstract

Dipicolinic acid (DPA) and the Ca2+ complex of DPA (CaDPA) are well-known and are major chemical components of bacterial spores. DPA's native fluorescence is very weak and is thought to be completely masked by the fluorescence of tryptophan when this compound is presented. Thus fluorescence related to DPA in spores is assumed by many authors to be completely absent. AWe show that the fluorescence of CaDPA is substantial for excitation between about 290 nm and 310 nm with emission peaking near 400 nm. This emission is at the long wavelength tail for emission form tryptophan. We examine whether the emission of CaDPA could contribute to the total emission spectrum when bacterial spores are present in an aerosol, for excitation wavelength in the neighborhood of 310 nm. In this report we present measurements of fluorescence excitation and emission for CaDPA and compare them with that of DPA and tryptophan.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.