ser + homocysteine -cystathionine + H2O

the biosynthesis of L-lysine by using strain-producer of lysine Corynebacterium glutamicum BKM Ac-2577 D (BIGOR 55). The strain obtained by mutagenesis of the parent strain W (PMBC Gosniigenetika) in OOO PKF "BIGORRE". The culture of Corynebacterium glutamicum BKM Ac-2577 D BIGOR 55 has genetic markers: leu and horn auxotroph and aminoacylation resistance, obligate aerobe, gram-positive, does not form spores. Cells in the form of rods of irregular shape, size from 0.3 to 1.0×1.5 to 4.7 µm, motionless. Are single or in pairs, often V-shaped;

cystathionine + H2O -- -ketobutyrate + cysteine + NH3

It is an important intermediate in arginine biosynthesisand in the urea cycle.
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(1) lysine,methionine,threonine

According to Nomura . (1987) QL-5, aspartate kinase was sensitive to feed back inhibition in the simultaneous presence of L-lysine and L-threonine. The simultaneous addition of these two s (1mM each) produced about 60% inhibition. The inhibition was reduced to about 40% by dialysis. Similarly, in L-lysine production by resting cells, the simultaneous addition of these two s (1mM each) produced 35% inhibition and dialysis reduced the inhibition to 12%. In dialysis cultures the lag-phase was shortened and cell mass increased, as compared to non dialysis culture. Moreover, in dialysis cultures, L-lysine was produced earlier and the maximum productivity of L-lysine (1.50 g L-1) was obtained in 6 through 10 hrs cultivation. Yokota and Shiio (1988), studied the effect of reduced citrate synthetase activity and feedback resistant phosphoenol pyruvate carboxylase on L-lysine productivities. Aspartokinase and S-2 aminoethyl cystein (AEC) resistant mutant plus threonine auxotroph of was found to produced more than 40 gL-1 of L-lysine as its HCl salt in the medium containing 10 % glucose. In particular, strain No. 664-7 with normally active and completely feed back resistant. AK produced 45g L-1 of L-lysine, HCl. A homoserine dehydrogenase-defective mutant (HD), H-3-4, with low level citrate synthetase and phosphoenol pyruvate carboxylase character also showed higher L-lysine productivity, 41 g / L, than the HD mutant, H1013, which was derived directly from the wild strain. Thus it was concluded that the low level citrate synthetase and phosphoenol pyruvate carboxylase character were effective for the enhancement of the L-lysine productivities of both aspartokinase resistant and HD type producers. Smekal . (1988) studied the control of L-lysine biosynthesis with chromogene mutants of Species M-27. They found 43 to 49 g L-lysine per liter in 96 hours with conversion of 45 to 49%.

(3) phenylalanine, Tyrosine, Tryptophan

Current availability of many complete genomes gives an opportunity to compare genes encoding one metabolic pathway and their regulation in a variety of bacteria. The comparative analysis is a powerful approach for prediction of the conserved RNA secondary structures and detection of novel regulatory RNA elements upstream of co-regulated genes in bacterial genomes (). In particular, highly conserved RFN, THI and B12 elements were identified in various bacteria upstream of genes involved in the biosynthesis of riboflavin, thiamin and cobalamin, respectively (–). In such studies, analysis of complementary substitutions in aligned sequences is used to construct a single conserved structure of an RNA regulatory element.

The glycolytic intermediate, 3-phosphoglycerate, is converted to serine,cysteine and glycine.
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Chapter 21 : Biosynthesis of Amino Acids, Nucleotides, …

has 3 isozymes of aspartokinase that respond differently toeach of the 3 amino acids, with regard to enzyme inhibition and feedbackinhibition. The biosynthesis of lysine, methionine and threonine are not, then,controlled as a group.

Amino Acid Synthesis and Metabolism

Kikuchi . (1996) claimed a new L-lysine decorboxylase of W 3110 and the DNA sequences, leading to high expression of L-lysine. Sergeichuk . (1995) examined that sp. and Micrococcal strains completely consumed L-lysine in the culture medium. Thus affected the level of L-lysine accumulation in the culture medium. Smirnov . (1994) isolated sp. from culture broth at different stages of fermentation during L-lysine production and found that this bacteria were not fastidious for culture conditions, grew rapidly, consumed a broad range of carbohydrate and actively produced extracellular slim protein-poly saccharide. They actively consumed the surrounding s thus were dangerous contaminants of biotechnological process.

LYSINE от офиц.поставщиков. Разумная цена. Бесплатная доставка

Samanta . (1988) isolated a number of methionine plus threonine double auxotrophs from a glutamate producing by mutagenesis with N-methyl-N-nitro-N-nitroso-guanidine. Sen and Chatterjee (1989) further studied the effect of B-Vitamins and trace element on L-lysine production by 2 Fa, which produced 2.6 g L-1 L-lysine. Addition of B-vitamins and trace elements to the optimal media has been found to stimulate growth and enhance L-lysine yield.