Effects of Dimethylsulfoxide on the Lactose Operon in Escherichia coli

AUTOR(ES)

Fowler, Audree V.

RESUMO

Fowler, Audree V. (University of California, Los Angeles), and Irving Zabin. Effects of dimethylsulfoxide on the lactose operon in Escherichia coli. J. Bacteriol. 92:353–357. 1966.—Dimethylsulfoxide (DMSO) at a concentration of 5% (v/v) in the culture medium inhibits the growth of Escherichia coli to only a slight extent, and does not affect the differential rate of synthesis of β-galactosidase. Resting cells remain viable after shaking in the presence of 20% DMSO for 3 hr at 37 C. Both β-galactosidase and thiogalactoside transacetylase retain almost all activity after incubation in even higher concentrations of the solvent for many hours. DMSO decreases the permeability barrier. The rate of hydrolysis of o-nitrophenyl-β-d-galactoside (ONPG) in whole cells containing β-galactosidase but lacking permease is increased in cells treated with 5% DMSO. Several permeaseless strains preinduced for β-galactosidase will grow on lactose in the presence, but not in the absence, of 5% DMSO. When permeaseless strains are grown on tetrazolium-lactose-agar, the presence of 5% DMSO causes a definite but not marked shift toward the lactose-positive character.

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