TITLE:
Optimization of Fermentation Conditions of Bacillus thuringiensis EC1 for Enhanced Methionine Production
AUTHORS:
V. N. Anakwenze, C. C. Ezemba, I. A. Ekwealor
KEYWORDS:
Bacillus, Methionine, Optimization, Submerged Medium, Maltose
JOURNAL NAME:
Advances in Microbiology,
Vol.4 No.7,
May
19,
2014
ABSTRACT: Bacillus thuringiensis EC1, isolated from the fermented
oil bean seed, Pentachletra macrophila Benthan, produced a methionine yield of 1.89 mg/ml. The influence of cultural
conditions on methionine accumulation by B.
thuringiensis EC1 showed that a 20% medium/fermenter volume ratio and a 5%
inoculum size increased methionine yield. The carbon of choice was maltose and
at 8% level stimulated methionine production. Among the nitrogen sources
studied, ammonium sulphate was found to be the best and at 1% concentration
produced a methionine yield of 2.56 mg/ml. All growth-promoting substances and
their mixtures enhanced methionine accumulation by B. thuringiensis EC1. The effect of Vitamins on methionine
production showed that riboflavin and thiamine HCl at 1.0 μg/ml yielded 2.49 mg/ml
and 2.80 mg/ml methionine respectively. The influence of bivalent metals on
methionine accumulation indicated that Zn2+ at all concentration
stimulated methionine production. Mg2+ and Ba2+ at 0.1 μg/ml
and 10.0 μg/ml respectively improved methionine yield. Optimizing the cultural
conditions of B. thuringiensis EC1 in
submerged medium gave a methionine yield of 3.18 mg/ml.