Perturbation by UV Light for Rapid Classification of Biological Particles by Fluorescence

摘要

Some time ago investigations were initiated into the fluorescence of calcium dipicolinic acid (CaDPA) to improve detection of bacterial endospores. Although the native chemical, CaDPA, fluoresced very weakly, the application of UV irradiation to CaDPA or DPA caused substantial blue-violet emission when excitation is applied later. Further investigation demonstrated a similar phenomenon for dry and wet endospores. The luminescence excitation-emission (Ex- Em or EEM) pattern of vegetative bacteria of various Bacilli as well as vegetative cells of other unrelated bacteria also changes markedly after UV irradiation. We found that the Ex-Em patterns for unirradiated bacteria taken together with the patterns after UV exposure provide a way to rapidly and inexpensively distinguish several different classes of biological particles and distinguish each of these from common background interferrants. In this report, the two dimensional experimental Ex-Em patterns using Parallel Factor Analysis and other modem pattern recognition techniques are analyzed. This analysis showed that gram positive bacteria and spores can be distinguished from gram negative bacteria, that vegetative bacteria can be distinguished from spores, and that all of these are distinguishable from certain common backgrounds using this potentially automatable technique.