Absolute emission spectra from Bacillus subtilis and Escherichia coli vegetative cells in solution

Abstract

Spectrally resolved emission (270-560 nm) from dilute suspensions of washed Bacillus subtilis and Escherichia coli were measured by use of tunable laser excitation between 270 and 300 nm. Integrated absolute emission cross sections increase with decreasing excitation wavelength and range from 1.8 x 10(-12) to 6.0 x 10(-11) cm(2)/(particle sr). An emission band near 340 nm dominates all observed spectra. At each excitation wavelength spectrally resolved emissions from the E. coli and B. subtilis suspensions are indistinguishable.

Aerosol Characteristics in a Subway Environment

“…Due to the fact that certain amino acids (principally tryptophan and tyrosine) fluoresce when excited near their absorption peaks in the ultraviolet (UV) region of the spectrum, a strong particle fluorescence signal indicates the presence of biological material since these amino acids occur in nearly all proteins. Therefore this spectroscopic characteristic was used to indicate the presence of biological aerosols (Seaver et al 1998;Faris et al 1997;Nachman et al 1996), and the SPFA provides both a total aerosol particle count rate and a biological particle count rate. For sizing, both the SPFA and the Met One instruments utilize the particles' optical scattering cross section to indicate size.…”

Background Aerosols and BW Detection: Problems and Suggested Solutions

“…Therefore, this spectroscopic characteristic was used to indicate the presence of aerosols of biological origin. 12 …”

Site U1382

“…AF43) indicated that microorganisms were heterogeneously distributed across the surface. Based on published fluorescence cross sections for bacteria (Seaver et al, 1998), the bacterial biomass for this sample is estimated to be ~10 4 cells/cm 2 . Signal intensities indicative of bacteria were generally associated with patches of iron oxides.…”