Principal component analysis of fluorescence changes upon growth conditions and washing of Pseudomonas aeruginosa

Abstract

We have measured the autofluorescence from suspensions of Pseudomonas aeruginosa in the growth medium and after one, two, and three washes. The bacterium was grown in two different media, nutrient broth and King's B broth. The bacterium was harvested after 12, 24, and 48 h of growth. The fluorescence was measured with excitation every 10 nm from 200 nm to 600 nm. The fluorescence profiles were analyzed using principal component analysis. We found that most of the information is in the first three principal components. Stark differences in the value of the first principal component were noted between the samples in broth and those with one, two, or three washings. The second and third principal components noted differences between the samples washed once and those washed two or three times. There was no significant difference between samples washed two and three times. There are small differences noted between the samples grown in the two different broths, and no differences were noted among the samples harvested at different times.

Separation and Analysis of Dynamic Stokes Shift with Multiple Fluorescence Environments: Coumarin 153 in Bovine β-Lactoglobulin A

“…Principle component analysis (PCA) is often used to decompose contributions to spectra in systematic studies of spectral evolution. – For the set of 39 temperature-dependent spectra in Figure , PCA produced unacceptably nonphysical results (not shown) by including unreasonably broad spectra with some components contributing negative intensities in the reconstruction. Because the concentration of C153 was ∼5 μ M, we expected reabsorption of fluorescence photons to be negligible and all spectral contributions to be positive.…”