COMPARATIVE STUDIES ON THE MECHANISM OF MICROBIAL GLUTAMATE FORMATION

II. EFFECT OF BIOTIN

Abstract

1. When Brevibacterium flavum No. 2247 (ATCC No. 14067) or Micrococcus glutamicus No. 534 (ATCC No. 13032) was cultured in biotin-rich medium, L-glutamate was not formed from glucose by either resting or growing cells, the resting cells of both strains oxidized glucose completely to carbon dioxide.
2. Enzyme activities which seem most closely related to glutamate formation did not change significantly with biotin concentration in the culture medium. An exception was isocitrate lyase activity in M. glutamicus. This enzyme was highly active in cell-free extracts prepared from biotin-rich cells, but hardly observed in cell-free extracts prepared from biotin-poor cells.
3. Marked differences of cellular permeability to glutamate between biotin-rich and biotin-poor cells of both strains were demonstrated with L-aspartate-α-ketoglutarate transaminase activity and with release of intracellular free glutamate on washing.
4. These results suggest that the "permeability hypothesis" proposed
previously with regard to the effect of biotin on the extracellular formation of glutamate would be also applicable in the case of M. glutamicus.