Easy Automated Genomic DNA Isolation for GMO Testing: From Vision to Reality

29980616-July25-PureFood---Kelly-600x300The European Union (EU) has a zero tolerance policy for products containing any material from non-authorized genetically modified (GM) crops. Seed entering EU markets may not contain even trace amounts of non-authorized genetically modified material. In 2012, as the global use of GM crops increased, seed testing loads in the EU continued to build. Isolating genomic DNA (gDNA) using traditional manual methods was becoming impractical in the face of increasing amounts of material that required testing. There was a growing need for an automated method to isolate gDNA from seed samples. Working to address this need, a group of scientists from the Bavarian Health and Food Safety Authority collaborated with scientists from Promega Corporation to evaluate the Maxwell® 16 Instrument and the associated chemistry as possible a solution for the testing labs.

The group’s criteria for an automated method was straight forward: an easy and fast protocol that produced high yields of DNA of sufficient purity for acceptable performance in downstream PCR assays. They began by evaluating two existing kits that were available for the Maxwell® 16 Instrument, one designed for DNA isolation from blood (Promega Cat.# AS1290) and one for RNA isolation from tissues (Promega Cat.# AS1220).  Neither kit produced acceptable results out of the box, so the group began to modify the protocol and chemistry using the Blood kit as the base. They added an incubation step with CTAB buffer and proteinase K. This created a new challenge, as some of the buffers in the kit were not compatible with CTAB. They then found that the negative effects of the CTAB buffer could be counteracted somewhat by adding the lysis buffer that came with the kit. However, the DNA was still not of sufficient purity, so they turned their attention next to the binding buffer. The existing binding buffer was switched out for a newly developed buffer (FFS buffer). The final result of the collaboration was a protocol and chemistries that worked with the Maxwell® 16 Instrument to isolate gDNA from corn, soya bean and rapeseed. In tests for GM presence, the DNA isolated with the new method performed as well or better than DNA isolated using the traditional manual methods, detecting GM content down to 0.033%. The group published their results in January of 2013 in the journal European Food Research Technology (1).

For others wanting to use the same method, Promega made it available on a custom order basis (Maxwell® 16 FFS Nucleic Acid Extraction System, Custom). This custom kit has now been reborn as the Maxwell® RSC PureFood GMO and Authentication Kit for the newest generation Maxwell® Instrument, the Maxwell® RSC.

This story highlights the power of collaboration in science. Product development can’t, and shouldn’t, happen in a vacuum. When manufacturers of science reagents work side-by-side with scientists in their labs, the ‘real world’ and the theoretical combine to develop something that is better than either might produce on their own.

Reference

  1. Guerlter, P. et al. (2013) Development of a CTAB buffer-based automated gDNA extraction method for the surveillance of GMO in Seed. Food Res. Technol. 236, 1–8.
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Kelly Grooms

Scientific Communications Specialist at Promega Corporation
Kelly earned her B.S. in Genetics from Iowa State University in Ames, IA. Prior to coming to Promega, she worked for biotech companies in San Diego and Madison. Kelly lives just outside Madison with her husband, son and daughter. Kelly collects hobbies including jewelry artistry, reading, writing, photography and knitting. She would like to be an avid runner, as evidenced by her growing collection of running gear and her single half-marathon finishers t-shirt.

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