Abstract

An investigation was carried out to produce mutant isolates from Bacillus subtilis UG1 and Bacillus licheniformis OG4 isolated from vegetable proteins using a chemical mutagen N-methyl-N-nitrosoguanidine (NTG) at dosage concentration of 250 µg/ml. The mutant isolates obtained from wild strain of B. subtilis UG1 produced mutants (M₁ to M₉) and was screened for hyper producing effect. Mutant M₁UG₁ was obtained. The mutant isolates obtained from wild strain B. licheniformis OG4, produced 11 mutants (M₁ to M₁₁) and when screened for hyper producing effect mutant M₆OG₄, was obtained. Hyper-producing mutant strains M₁UG₁ and M₆OG₄ produced L-glutamic acid of 23.0 mg/ml respectively. The quantity produced was higher than the glutamate obtained from Corynebacterium glutamicum ATCC 13032 (14 mg/ml). The developed mutant strain was better adapted to a shift in temperature range of 55 to 60°C, pH 9.0 and biotin concentration of 10 µg/ml. As part of the programme to increase glutamate yields and to use materials of agro-industrial wastes, the developed mutants M₁UG₁and M₆OG₄ were found to utilize the tested agro-industrial wastes maximally for growth and glutamic acid production.

Key words: L-glutamic acid, agro-industrial wastes, mutants, N-methyl-N-nitrosoguanidine (NTG), fermented vegetable proteins.