[01] Musa B., Department of Microbiology, Faculty of Science, Ahmadu Bello University, Zaria, Nigeria. [02] Ado S. A., Department of Microbiology, Faculty of Science, Ahmadu Bello University, Zaria, Nigeria. [03] Abdullahi I. O., Department of Microbiology, Faculty of Science, Ahmadu Bello University, Zaria, Nigeria.

The present study was an investigation on comparative L-glutamic acid production by wild-type and a mutant strain of Corynebacterium glutamicum using rice bran pretreated with H₂SO₄ and KOH. Owing to the high carbohydrate (Cellulose) content of acid-treated and alkali-treated rice bran as determined (64.25% and 76.37% respectively), attempt was made to utilize the rice bran for the production of glutamic acid by submerged fermentation. The acid-treated and alkali-treated rice bran at concentration of 4% gave the highest glutamic acid yield of 27.84g/L and 15.72g/L respectively with the developed mutant strain (CG^NTA) under predetermined optimum fermentation conditions. In contrast, lower yields of 10.40g/L and 9.08g/L respectively were obtained with the wild-type strain under similar optimum culture conditions. Out of four parameters optimized, substrate concentration and inoculum size were found to significantly (p˂0.05) influence glutamate production by CGNTA, but only pH variation was found to be significant on the performance of the wild-type strain in glutamate production. Acid-treated rice bran hydrolysate was determined to be a better substrate for L-glutamate production by the CG^NTA mutant than the wild-type strain of C. glutamicum. The mutant strain (CG^NTA) developed could therefore be useful in the industrial production of glutamic acid using rice bran as substrate.

Rice Bran, Wild-Type, Mutant (CG^NTA), C. glutamicum, Fermentation, Glutamate

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