METABOLISM OF LACTOSE BY LEMNA-MINOR-L (DUCKWEED) CALLUS

The callus of Lemna minor L. (duckweed) is capable of heterotrophic as similation of galactose and beta-lactose, whereas the intact plant is not. Sucrose-grown callus adapted rapidly, uniformly, and reversibly t o utilization of galactose or lactose in heterotrophic growth. Single- nutrient deficiencies of callus growth medium were corrected fully by milk whey; the lactose of milk whey was utilized Lemna callus grows we ll at pH 4.0-6.5 and tolerates 0.05% (5.5 mM) lactic acid at pH 5.0 wi th slowed growth. Preliminary data using elude extracts of callus reve aled higher specific activities of enzymes of lactose and galactose me tabolism: beta-galactosidase, galactokinase, UDP gal pyrophosphorylase , and inorganic pyrophosphorylase. Lemna minor callus should be able t o consume sweet-cheese whey.