Detection and Cross Contamination Evaluation of Roundup Ready Soy via Mechanical Shear Homogenization using the GLH-850

Genetically Modified (GM) crops are food products that have had their DNA modified to introduce new traits such as resistance to pests, diseases or environmental conditions. One popular GM crop is Roundup Ready® soy by Monsanto. Roundup Ready® soy is genetically engineered soybeans designed to be tolerant of the herbicide Roundup®. The Roundup® herbicide is a glyphosate that inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) (1). EPSPS catalyzes an essential step in the biosynthesis of the amino acids phenylalanine, tyrosine and tryptophan in plants (2). When sprayed Roundup® quickly inhibits the growth of plants by interfering with the synthesis of these essential amino acids. Roundup® is typically used to inhibit the growth of weeds but usually at the cost of reduced crop yields. Roundup Ready® soybeans have been genetically engineered to express a version of the EPSPS gene that confers resistance to glyphosates therefore allowing it to survive the doses required to kill weeds that infect farmers fields (1).

In order to determine the detection of Roundup Ready® soy, the soy products are homogenized and the DNA is extracted using a variety of techniques. Following extraction, the genetically modified EPSPS gene is detected via Polymerase Chain Reaction (PCR). Rotor stator homogenizers are one of the preferred methods for processing a variety of samples from soybeans to soy powder. The Omni GLH 850 is a programmable rotor stator homogenizer that can quickly process samples at speeds of up to 25,000 RPM and sample volumes up to 10 liters.Particularly, the Omni GLH 850 can process samples using a variety of stainless steel and Omni TipTM plastic homogenizing probes. Omni Tip plastic homogenizing probes can process a range of sample matrices and can significanty reduce cross-contamination, samples loss and carryover concerns when dealing with PCR assays.

Herein, we evaluate the Omni GLH 850’s capability of processing a variety of soy sample matrices for the detection of Roundup Ready® soy. In conjunction, the potential for sample cross contamination from the use of a standard stainless steel generator probes was evaluated.

Table 3. Soybean and soy powder DNA concentrations