Examination of DNA extract from kernels and processed foods using silica-base resin

Abstract

A rapid and simple DNA extraction method is needed to detect genetically modified recombinant DNA in soybean kernels and processed foods. However, since various kernels and processed foods differ greatly in form, a uniform DNA extraction method has proved elusive. The silica-base resin DNA extraction method does not use any organic solvent, and the operation is simple and the cost per extraction is low, although the frequency of its use is very low and few domestic reports exist. We therefore studied suitable conditions for a silica-base resin method. We also developed the method to get more pure DNA from soybean kernels. The silica-base resin method was found to be adequate for extracting DNA from various processed foods for PCR amplification with endogenous gene primers. In the case of DNA extraction from soybean kernels, pure DNA could be efficiently extracted after pre-heating the soybean suspension in TNE buffer. The extracted DNA showed higher ratios of absorption at 260 nm/280 nm and 260 nm/230 nm than those for samples obtained with previous methods. Moreover, our observations suggested that the extraction time could be reduced to within 30 min for processed foods such as tofu.