Improved protocol for recovery of bacterial DNA from water filters: Sonication and backflushing of commercial syringe filters.

Extraction of bacterial DNA from water filters is frequently used in aquatic microbial ecology, e.g., for sequencing-based diversity studies. Here, we describe an improved size-class filtration and bacterial DNA extraction protocol using commercial "syringe filters", involving sonication- and backflushing-steps and DNA-binding magnetic beads. Importantly, the sonication-step improved DNA recovery up to 10-fold. The DNA extraction-turnaround time is 4h, with a hands-on time of about 2h.