A DTSR GENE-DISRUPTED MUTANT OF BREVIBACTERIUM-LACTOFERMENTUM REQUIRES FATTY-ACIDS FOR GROWTH AND EFFICIENTLY PRODUCES L-GLUTAMATE IN THE PRESENCE OF AN EXCESS OF BIOTIN

A dtsR gene encoding a homolog of the beta subunit of some biotin-cont aining enzymes suppresses a detergent-sensitive mutation of Brevibacte rium lactofermentum (E. Kimura et al., 1996, Biosci. Biotech. Biochem. 60, 1565-1570), which has been used for the fermentative production o f L-glutamate. When the dtsR gene was disrupted, the organism exhibite d strict fatty acid auxotrophy; oleate or oleate ester, but not palmit ate ester or stearate ester, supported the growth of the Delta dtsR mu tant. Immunoblotting with an anti-DtsR antibody revealed that no intac t DtsR was present in the cytosol of the Delta dtsR mutant. In the pre sence of an excess of biotin, the wild type strain did not produce L-g lutamate whereas the Delta dtsR mutant efficiently produced it. The me chanism underlying the efficient production of L-glutamate by the Delt a dtsR mutant is discussed as to the possible role of dtsR in fatty ac id metabolism. (C) 1997 Academic Press.