Effect of oxygen supply on L-lysine, L-threonine and L-isoleucine fermentations.

Abstract

Effect of oxygen tension on L-lysine, L-threonine and L-isoleucine accumulation was investigated.Sufficient supply of oxygen to satisfy the cell's oxygen demand was essential for the maximum production in each fermentation.The dissolved oxygen level must be controlled at greater than 0.01 atm in every fermentation, and the optimum redox potentials of culture media were above -170mV in L-lysine and L-threonine and above -180mV in L-isoleucine fermentations.The maximum concentrations of the products were 45.5mg/ml for L-lysine, 10.3 mg/ml for L-threonine and 15.1 mg/ml for L-isoleucine. The degree of the inhibition due to oxygen limitation was slight in the fermentative production of L-lysine, L-threonine and Lisoleucine, whose biosynthesis is initiated with L-aspartic acid, in contrast to the accumulation of L-proline, L-glutamine and L-arginine, which is biosynthesized by way of L-glutamic acid.

Improvement of the Redox Balance Increasesl-Valine Production by Corynebacterium glutamicum under Oxygen Deprivation Conditions

“…Current production, estimated to be in excess of two million tons per year, is predominantly from fermentation of sugars (14,24). Conventional amino acid fermentation is an aerobic process requiring cell growth and, consequently, sufficient aeration or appropriate control of dissolved oxygen or redox potential of the culture medium in order to achieve high productivity (2). Moreover, under aerobic conditions, the carbon source, besides being the substrate from which the amino acids are directly produced, is also consumed during cell growth.…”

Role of Cytochrome bd Oxidase from Corynebacterium glutamicum in Growth and Lysine Production

“…Several studies have indicated the importance of proper oxygenation conditions under manufacturing operations to attain high amino acid yields (2,29,38). In addition, overexpression of the glbO gene encoding a hemoglobin-like protein was shown to improve lysine synthesis (21).…”

Optimization of L‐phenylalanine production of Corynebacterium glutamicum under product feedback inhibition by elevated oxygen transfer rate

“…These ®ndings indicate that the biosynthetic enzymes of phenylalanine are not deregulated completely in these mutants and recombinants, which becomes the major factor limiting end-product accumulation. This might also explain the results of several investigations, in which the maximum phenylalanine concentrations were less than 17 g/L even though their processes were optimized by oxygen supply rate control (Akashi et al, 1979a), glucose feeding strategy (Hwang et al, 1985), and phosphate limitation control (Choi and Tribe, 1982).…”

“…Along with the progress of strain improvement, various fermentation strategies have been developed to improve phenylalanine concentration and volumetric productivity, including oxygen supply rate control (Akashi et al, 1979a;Konstantinov et al, 1991), glucose feeding rate (Choi and Tribe, 1982;Forberg et al, 1988;Hwang et al, 1985;Takagi et al, 1996), temperature (Sugimoto et al, 1990), and non-growing culture (Weikert et al, 1998). Although end-product removal techniques are common solutions used to enhance product yields whenever product inhibition is present, only rarely have attempts succeeded in phenylalanine fermentation process.…”