The present invention is directed to a method for separating, characterizing and/or identifying microorganisms in a test sample. The method of the invention comprises an optional lysis step for lysing non-microorganism cells that may be present in a test sample, followed by a subsequent separation step. The method may be useful for the separation, characterization and/or identification of microorganisms from complex samples such as blood-containing culture media. The method may also be useful for the physical separation and/or enrichment of two or more different or individual microorganism species contained in a mixed test sample. The invention further provides for spectroscopic interrogation of the separated microorganism sample(s) to produce measurements of the microorganism and characterizing and/or identifying the microorganism(s) in the sample using said spectroscopic measurements.