Optical determination of bacterial exosporium sugars using immobilized porphyrins

Abstract

Three porphyrins were tested as possible candidates for identification and quantification of the presence of sugars known to be contained in the exosporium of the bacterial endospores of some Clostridium and Bacillus species. The effect of the sugars on both absorbance and fluorescence characteristics of the immobilized porphyrins was investigated for possible application as a wipe test to indicate the presence of these sugars. Changes in porphyrin absorbance spectra were unique for each sugar with limits of detection as low as 2 ppb using immobilized porphyrins and 0.2 ppb using porphyrins in solution. Meso-tetra(4-boronic acid) porphyrin (TPPB) is likely the most useful porphyrin of those tested for detection of the sugars. Detection of methyl a-L-rhamnopyranoside between 13 and 1450 parts per billion (ppb), L-rhamnose between 15 and 150 ppb, L(-)-fucose between 80 and 1300 ppb, and D(+)-galactosamine between 18 and 1700 ppb is demonstrated using TPPB.