Change in Permeability to L-Glutamic Acid in the Glycerol Auxotroph GL-21

Abstract

In this study, the mechanism of the extracellular accumulation of l-glutamic acid by the glycerol auxotroph was partially clarified. Whenever Corynebacterium alkanolyticum GL–21 (glycerol auxotroph) accumulated a large amount of l-glutamic acid in the fermentation broth, the content of its cellular phospholipids was not more than 50% of that of C. alkanolyticum No. 314 (prototroph).Moreover, biotin, oleic acid or thiamine had no influence on the cellular phospholipid content of the auxotroph.Under limited supply of glycerol, the efflux of l-glutamic acid in the auxotroph was extremely enhanced, but its enzyme activities participating in l-glutamic acid biosynthesis remained at the same level as those of the prototroph.From the results, it is considered that the regulation of phospholipid content gave rise to the destruction of the permeability barrier to l-glutamic acid in the cell membrane.