Fluorescence detection of proteins released by Bacillus subtilis spores during heat shock germination

Fluorescence and absorption spectroscopy were performed on Bacillus subtilis spores which were heat treated at temperatures ranging from 20 degrees C to 90 degrees C. The tryptophan (trp) emission from the spore suspensions treated at temperatures greater than 60 degrees C was shifted towards longer wavelength as compared to the spores which were heat treated at lower temperatures. These spectral changes were the result of proteins released by the spores into the suspension. Tip residues in the emitted proteins are in a more polar environment and therefore exhibit a larger Stokes shift. Fluorescence and absorption measurements show that the concentration of proteins in the supernatant was greater for spores treated at higher temperatures. Electrophoresis gel analysis showed the presence of a 47 KDa protein in the supernatant.