Selective isolation of bacteria for metagenomic analysis: Impact of membrane characteristics on bacterial filterability.

For indirect DNA extraction for metagenomics studies, bacterial cells can be effectively separated from sample debris by using a simple size exclusion technique, such as filtration, and thereafter lysed. The requirement for the optimal recovery of cells in filtrates is critical to achieve sufficient DNA yield and a representative population. Particles smaller than the filter pore size are expected to be found in the filtrate, whereas particles larger than the filter pore sizes are excluded. However, this is not always the case. It is established that the membrane pore size influences filtration efficiency to some degree. In addition the physicochemical characteristics of the filter suspension and characteristics of the microbial cells being filtered influence the exclusion property of a membrane. This review provides an overview of membrane filtration techniques and the factors that affect filterability of bacteria cells through a filter membrane.