Reproducibility and sensitivity of polarized light scattering for identifying bacterial suspensions

Reproducibility and sensitivity of polarized light scattering measurements are explored for a particular rodlike bacterial species in different growth conditions. The angle dependence of certain Mueller scattering matrix elements (primarily S(34)/S(11)) is used to measure these features. The angular S(34)/S(11) scattering pattern was found to be strongly correlated with bacterial cell size. In view of the large changes found for different growth conditions, it is concluded that much improvement in the technique of recognizing scattering patterns would be needed before the angle dependence of a given Mueller matrix element can be unequivocally associated with a given bacterial strain. The sensitivity of S(34)/S(11) patterns (at a wavelength of 633 nm) to changes in internal structure of the bacteria was tested by following the pattern after virus particles were produced inside the individual bacteria by an induction procedure. No appreciable changes occurred up until the time the bacteria were lysed (destroyed) by the process.