Spectral absorption of prodigiosin in intact cells.

a simple acetone extraction process which they used in studying the spectral absorption of prodigiosin and 4 fractions separated by paper chromatography. It is possible, however, to study the spectral absorption of the pigment while it is still in the cells. The absorption spectra of the extract and the whole cells should agree if the extraction process does not affect the pigment; the native pigment is not shielded or altered by its association with other cellular components; and the method used with whole cells truly eliminates the effect of scattering. Bateman and Monk (1955) described a new method of measuring the true absorption of turbid suspensions using diffuse light and referred to several earlier methods reported in the literature. The method used in this work also employs the principles of diffuse light spectrophotometry. It consists of adding the absorbing system to a heavy suspension of a scattering substance in a wide cell and measuring the transmission of the diffuse slab in a double beam spectrophotometer. The added scattering due to the sample is insignificant and its absorption alone determines the transmission of the slab relative to a similar slab without absorber in the reference beam.