NUCLEIC-ACID AND PROTEIN ELIMINATION DURING THE SUGAR MANUFACTURING PROCESS OF CONVENTIONAL AND TRANSGENIC SUGAR-BEETS

The fate of cellular DNA during the standard purification steps of the sugar manufacturing process from conventional and transgenic sugar be ets was determined. Indigenous nucleases of sugar beet cells were foun d to be active during the first extraction step (raw juice production) which was carried out at 70 degrees C. This and the consecutive steps of the manufacturing process were validated in terms of DNA degradati on by competitive PCR of added external DNA. Each step of the process proved to be very efficient in the removal of nucleic acids. Taken tog ether, the purification steps have the potential to reduce the amount of DNA by a factor of > 10(14), exceeding by far the total amount of D NA present in sugar beets. Furthermore, the gene products of the trans genes neomycin phosphotransferase and BNYVV (rhizomania virus) coat pr otein CP21 were shown to be removed during the purification steps, so that they could not be detected in the resulting white sugar. Thus, su gar obtained from conventional and transgenic beets is indistinguishab le or substantially equivalent with respect to purity. (C) 1998 Elsevi er Science B.V. All rights reserved.