Kellogg Co., the maker of Frosted Flakes and Special K cereals and other products, has shut down a Michigan plant because it could not guarantee corn used in production would be free of a genetically modified grain approved only for animal consumption, The Washington Post reported Saturday. The location of the plant was not specified and Kellogg officials would not confirm the shutdown. Big grain suppliers are unable to certify that their corn is not mixed with the gene-altered corn, called StarLink, linked to a nationwide recall in the U.S. of taco shells. Aventis CropScience, which makes the corn, is trying to recover 9 million bushels that may be heading to food companies, the paper continued.