Optimising Carbon and Nitrogen Sources for L-Glutamic acid Production by Brevibacterium strain NIAB SS-67

Glutamic acid has attracted attention for its pharmaceutical and food applications. There is a 13.3% annual market growth and needs extensive research work on its over-production using new organisms or innovative technology. To increase glutamate yield and productivity, we used Brevibacterium strain NIAB SS-67 and got 38 g glutamic acid/L of glucose-trypticase (L-6) medium (pH 7.0) at 30 degrees C. Further enhancement in glutamate production was sought by optimising C and N sources using research techniques. Out of nine C sources (glucose, galactose, dextrin, lactose, maltose, sorbose, xylose, fructose, sucrose) and six N sources (urea, ammonium chloride, ammonium sulphate, ammonium nitrate, ammonium phosphate, potassium nitrate and sodium nitrate) tested, 12% dextrin and 2% ammonium sulphate revealed the best results, yielding up to 60.8 g glutamic acid/L (50% enhancement) after 48 h fermentation. Product yield (0.23 g/g on glucose medium) increased to 0.61 g/g with glutamic acid volumetric productivity of 2.1 g/L h, which is 1.75-fold higher than that reported on other Brevibacterium strains, grown under identical growth conditions