Effect of Soybean Protein Concentrate Preparation on Copy Numbers and Structural Characteristics of DNA from Genetically Modified Soybean

To regulate the degradation of transgenic DNA and lay theoretical foundations for the rational utilization of genetically modified (GM) products, variations in copy numbers and structural characteristics of DNA from GM soybean event GTS 40-3-2 during soybean protein concentrate (SPC) preparation were evaluated. Results showed that defatting and the first ethanol extraction were key procedures inducing DNA degradation. After these two procedures, copy numbers of the lectin and cp4 epsps targets decreased by more than 4 x 10(8), occupying 36.88-49.30% of the total copy numbers from raw soybean. Atomic force microscopy images visually revealed the degradation of DNA that thinned and shortened during SPC preparation. Circular dichroism spectra suggested a lower helicity of DNA from defatted soybean kernel flour and a conformation transition of DNA from B-type to A-type after ethanol extraction. The fluorescence intensity of DNA decreased during SPC preparation, verifying the DNA damage along this preparation chain.

Automated summary

This study evaluated the degradation of transgenic DNA during the preparation of soybean protein concentrate (SPC) from GM soybean event GTS 40-3-2. The results showed that defatting and the first ethanol extraction were key procedures leading to DNA degradation. The copy numbers of specific DNA targets decreased significantly after these procedures, and the atomic force microscopy images confirmed the thinning and shortening of DNA during SPC preparation. Circular dichroism spectra revealed changes in DNA helicity and conformation transition, and the fluorescence intensity of DNA decreased, indicating DNA damage during the SPC preparation.