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OPTIMIZING THE CONCENTRATION OF BIOTIN FOR L-GLUTAMIC ACID PRODUCTION BY A LOCALLY ISOLATED CORYNEFORM STRAIN

Various concentrations of biotin were tested in order to achieve fluent excretion of glutamic acid (glu) in a fermentation medium composed of a locally isolated Corynebacterium glutamicum strain. The behaviour of the strain was observed to vary with varying concentrations of biotin. Maximum values for specific growth rate (μ, h-1), cell mass yield (Yx/s, g/g), substrate consumption rate (QS, g/l h) and cell mass specific productivity (qX, g/g h) were 0.34, 0.24, 2.92 and 1.43, respectively, given 10 μg biotin/100 ml under working conditions of a shake flask with temperature 30 °C, in 100 g glucose/l medium (pH 7.0). The kinetic parameters calculated for glutamate production under the above conditions were 4.94 g/l h, 4.4 g/g cells, 0.66 g/g, and 1.5 g/g .h for QP, YP/X, YP/S, and qP, respectively, and were comparatively higher than the respective values reported for some C. glutamicum strains growing on glucose in batch culture studies. Conversely, at biotin concentrations of 1.0, 2.5, 5.0, 15 μg/ ml, significantly less improvement in glu production was noticed, but at 10 μg/ml a nearly 2.2-fold increase in QP was observed, though the only statistically significant difference was in the QS value.