Effect of cysteine on methionine production by a regulatory mutant of corynebacterium lilium

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Author: Dharmendra Kumar; Subramanian, Kartik; Bisaria, Virendra S; Sreekrishnan, T R; Gomes, James
Advisor: Advisor
Date: 2005
Publisher:
Citation: Bioresourc
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Item Type: Article
Keywords: Glc6P; glucose-6-phosphate; Fru6P; fructose-6-phosphate; GaP; glyceroldehyde-3-phosphate; G3P; 3 phosphoglycerate; PEP; phosphoenol pyruvate; Pyr; pyruvate; AcCoA; acetyl coenzyme A; OaA; oxaloacetate; Isocit; isocitrate; aKG; alpha keto glutarate; SucCoA; succinyl coenzyme A; Suc; succinate; Mal; malate; Asp; aspartate; O-Shs; orthoacetylhomoserine; Meth; methionine; Lys; lysine; Thr; threonine; Ribu5P; ribulose 5 phosphate; Rib5p; ribose 5 phosphate; Xyl5p; xylulose 5 phosphate; Sed7P; sedoheptulose 7 phosphate; E4P; erythrose 4 phosphate; ADP; adenosine diphosphate; NADH; reduced nicotinamide adenine dinucleotide; FADH; reduced flavin adenine dinucleotide; NAD; nicotinamide adenine dinucleotide; FAD; flavin adenine dinucleotide; ATP; adenosine triphosphate
Abstract: The production of methionine by submerged fermentation using a mutant strain of Corynebacterium lilium was studied to determine suitable conditions for obtaining high productivity. The mutant strain resistant to the methionine analogues ethionine,norleucine, methionine sulfoxide and methionine methylsulfonium chloride produced 2.34 g1 of methionine in minimal medium containing glucose as carbon source. The effect of cysteine on methionine production in a 15 l bioreactor was studied by supplementing cysteine intermittently during the course of fermentation. The addition of cysteine (0.75 g1 h1) every 2 h to the productionm medium increased the production of methionine to 3.39 g1. A metabolic flux analysis showed that during cysteine supplementation the ATP consumption reduced by 20%. It also showed that the increase in flux from phosphoenol pyruvate to oxaloacetate leads to higher methionine production. Results indicate that controlling the respiratory quotient close to 0.75 will produce the highest amount of methionine and that regulatory mutants also resistant to analogues of cysteine would be better methionine over producers.