The population observations discuss

The population observations discussed above are typically specific to a fraction of the microbial population due to sample collection (e.g.,filter size).Further fractionation can be achieved using additional methods (e.g., fluorescence-activated cell sorting). For example, Lesur & Campbell (2004) used elutriation to fractionate yeast populations based on their replicative age and then performed transcriptomic analysis on the fractions, and Martín-Figueroa et al. (2000) observed differential gene expression of vegetative and heterocyst cells in the nitrogen-fixing cyanobacteria Anabaena.