The described application reveals that laser nephelo-metry is a reliable technique for monitoring microbial growth besides the classical applications like compound solubility testing and immunoprecipitation. Studies show that the nephelometric assay, compared to the turbidimetric assay, is not only comparable, but clearly superior regarding sensitivity. The key advantage of nephelometry is the ability to detect scattered light, even if the concentration of scattering particles is very low, which is the case during the lag phase and beginning of the log phase. Using the NEPHELOstar Plus, instead of a traditional transmission reader, this early part of the growth curve can be monitored much more accurately.
Nephelometry is a direct method of measuring light scattered by particles suspended in solution at right angles to the beam, or preferably, at a forward angle. In dilute solutions, where absorption and reflection are minimal, the intensity of the scattered light is a function of the concentration of scattering particles such as microbes.
In this application note, the only laser-based microplate nephelometer was used to monitor growth of the Corynebacterium glutamicum. Relative nephelometric units detected by the NEPHELOstar® Plus were compared to OD600 absorbance measurements and revealed that both density measurements correlated well, with nephelometry being the more sensitive method.