Established in the mid 1970's, New England Biolabs, Inc. (NEB) is the industry leader in the discovery and production of enzymes for molecular biology applications and now offers the largest selection of recombinant and native enzymes for genomic research. NEB continues to expand its product offerings into areas related to PCR, gene expression, sample preparation for next generation sequencing, synthetic biology, glycobiology, epigenetics and RNA analysis. Additionally, NEB is focused on strengthening alliances that enable new technologies to reach key market sectors, including molecular diagnostics development. New England Biolabs is a privately held company, headquartered in Ipswich, MA, and has extensive worldwide distribution through a network of exclusive distributors, agents and seven subsidiaries located in Canada, China, France, Germany, Japan, Singapore and the UK. For more information about New England Biolabs visit neb.
I was becoming a bit bored with the tedium of column-based kits, so when I had to isolate genomic DNA from a range of micro-organisms for a recent project I decided to try something new.
Invitrogen’s ChargeSwitch genomic DNA isolation kit, which uses magnetic beads to separate the gDNA from the cell debris, seemed interesting so I thought I’d give it a go.
The initial outlay for the kit is higher than most since a specialized rack with integrated magnets is required. The racks cost upwards of 100 GBP depending on the size. Since I only needed the mini-prep rack, my boss wasn’t too upset at the price.
The kit uses a unique magnetic bead material that is positively charged, so forms an ionic bond with the negatively charged DNA backbone, at low pH but loses this charge and DNA binding ability at higher pH (see diagram above). After a standard lysis procedure, the genomic DNA can be isolated in a 15 minute procedure that involves binding the genomic DNA to the magnetic beads in a low pH buffer, immobilizing the beads with a magnet, washing and finally eluting in a higher pH buffer (click the thumbnail image on the left for a visual description).
Although the protocol advises that centrifugation is not required after the initial pelleting of the cells, I found that centrifugation after the lysis step (e.g. 14,000 rpm, 10 min) was required to prevent contamination of the final eluate with cell debris.
That said, I was delighted that yields and purities of the genomic DNA samples I obtained from this kit were easily better than I normally obtain with column-based kits, so I would definitely recommend giving this kit a go.
Invitrogen have kits for plasmid DNA and RNA isolation that use the same ChargeSwitch technology, so I think I will be giving these a go and getting rid of at least some of my column-based kits!