Enzyme activities of 2-oxoglutarate dehydrogenase complex and glutamate dehydrogenase of wild type Brevibacterium lactofermentum, one of the typical glutamate-producing coryneform bacteria, were investigated by using cells cultured under glutamate-productive and glutamate-non-productive conditions. Significant reduction of the former enzyme activity was observed in the cells under the several glutamate-productive conditions, namely, in the cells cultured in media containing a) limited concentrations of biotin, b) sub-lethal amounts of penicillin, and c) sub-optimal amounts of a surface-active agent, as compared with those under the non-productive conditions. The activity of the latter enzyme was essentially unchanged in every condition. The relationship between glutamate production and the enzyme activities as well as permeability of glutamate through cell membrane was discussed from the results obtained.