The regulation of carbohydrate metabolism in animal cells: isolation of starch- and maltose-utilizing variants.

Chinese-hamster ovary (CHO-K1) cells can grow in medium in which glucose is replaced by either maltose, trehalose, or starch. This growth is due to the presence in the medium of serum enzymes which degrade these substrates to glucose. When the enzymes are inactivated by heat treatment, the cells no longer grow on these substrates but still grow on glucose. Medium containing heat-inactivated serum and the appropriate substrate in place of glucose has been successfully used to isolate starch- and maltose-utilizing variants of CHO-K1 cells.