L-Glutamic acid production by Bacillus spp. isolated from vegetable proteins

Abstract

22 isolates of Bacillus species were obtained from “Dawadawa”, “Ugba” and “Ogiri” (fermented vegetable proteins) in Nigeria. The isolates were identified as Bacillus subtilis (6), (27.3%), Bacillus pumilus (5), (22.7%), Bacillus licheniformis (5), (27.3%) and Bacillus polymyxa (6), (22.7%). Four species of the Bacillus isolates were selected based on their ability to grow and produce L- glutamic acid in a synthetic medium and their comparison with the reference strain Corynebacterium glutamicum ATCC 13032. The four Bacillus species were B. subtilis (UGI). B. pumilus (DD4), B. licheniformis (0G4) and B. polymyxa (OG7) isolated from “Ugba”. “Dawadawa” and “Ogiri”, respectively. All the 22 Bacillus species isolated produced L- glutamic acid with B. subtilis (UGI) from “Ugba” recording the highest (8.5 mg/ml), while B. licheniformis (OG4) from “Ogiri” had the lowest value (5.0 mg/ml). L-Glutamic acid produced by B. subtilis (UGI) from “Ugba” (8.5 mg/ml) compared favourably with that produced by the reference strain C. glutamicum ATCC 13032, (10.2 mg/ml). All the isolates were able to utilize a range of carbon sources with glucose been the best, giving a yield of 8.4 mg/ml, while galactitol was least utilized. Ammonium nitrate was the best nitrogen source (6.5 mg/ml), while asparagine was least utilized (3.40 mg/ml) by the test isolates.

Key words: L-Glutamic acid, bacteria strains, fermented vegetable proteins, fermentation.