Penetration of Mannitol into the Intracellular Space of Chlorella sorokiniana.

It was found that in the alga, Chlorella sorokiniana, mannitol penetrated the plasmalemma (normally thought to be impermeable to mannitol) into the intracellular space. The rate of penetration is exponential and relatively slow, having a half-time of 6 to 12 minutes and requiring over 60 minutes for complete penetration. This penetration was demonstrated both by the Millipore filtration of cells incubated with (14)C-mannitol and by centrifugation of the cells through a silicon oil layer after incubation with tritiated water and (14)C-mannitol. Further, mannitol caused an inhibition of both autotrophic (on CO(2)) and heterotrophic (on glucose) growth. A low rate of mannitol metabolism was demonstrated, although this rate could not support heterotrophic growth.