202 results about "Feedback inhibition" patented technology

A method for optimization of a fed batch hydrolysis process wherein the hydrolysis time is minimized by controlling the feed addition volume and / or batch addition frequency of the prehydrolysate and optionally also the enzyme feed. The increase over time in hydrolysate consistency and volume and / or concentration of sugars released in the reactor, so that the enzymatic hydrolysis is controlled, significantly reduces the impact of cellulase feedback inhibition, especially for enzyme contents lower than 0.5%. The overall time to reach conversion of the total prehydrolysate feed is reduced significantly where the batch addition frequency is equal to one batch each time 70% to 90%, preferably 80%, conversion of the previous batch is reached in the reaction mixture. At an enzyme load of 0.3% in the reaction mixture, the optimum frequency each time 80% conversion was reached was found to be one batch every 105 minutes.

O-acetylserine, L-cysteine and sulphurous compounds derived therefrom may be produced using a bacterium belonging to the genus Escherichia which harbors a mutant feedback-resistant serine acetyltransferases in which the amino acid sequence corresponding to positions from 89 to 96 in a wild-type serine acetyltransferase is replaced with any one of the amino acid sequences shown in SEQ ID NOS: 4 to 9, and feedback inhibition by L-cysteine in the bacterium is desensitized.

Production of alcohol from mixed microbial pool degradable and fermented lignocellulose substance is carried out by crushing lignocellulose substance, soaking with H2SO4, bursting by steam, solid-liquid separating, adding nutritive liquid into solid-phase substance, sterilizing, adding distiller's yeast and cellulose degrading microbe into saccharifying fermentative substrate, degradation saccharifying-fermenting synchronously, distilling and rectifying to obtain final product. It is simple, has short saccharifying and fermenting period, higher raw material utilization rate and more alcohol yield and no feedback inhibition function.

An L-amino acid is produced by culturing a Methylophilus bacterium which can grow by using methanol as the main carbon source and has L-amino acid-producing ability, for example, a Methylophilus bacterium in which dihydrodipicolinate synthase activity and aspartokinase activity are enhanced by transformation of cells with a DNA coding for dihydrodipicolinate synthase that is desensitized to feedback inhibition by L-lysine and a DNA coding for aspartokinase that is desensitized to feedback inhibition by L-lysine, or a Methylophilus bacterium which is casamino acid auxotrophic, in a medium containing methanol as a main carbon source, to produce and accumulate an L-amino acid in culture, and collecting the L-amino acid from the culture.

The invention discloses a high-density fermentation method of engineering bacteria containing nitrilase. The method adopts a novel recombinant Escherichia coli fermentation and supplementary material culture medium formula, and uses a method of DO-STAT coupling step-by-step induction and gradual increase of the speed stage by stage. The method not only meets the need for mixing power in the culture process with biomass increase, effectively controls the growth rate of thalli, and prevents disadvantages of produced acid accumulation caused by fast growth of thalli, feedback inhibition and culture medium waste. In addition, the induced mode of batch-by-batch lactose supplement addition avoids the high viscosity of the fermentation broth caused by high concentration of lactose, resulting in resistance of oxygen transfer and mass transfer, but also improves the induction strength. The high-density fermentation technology of the invention increase the biomass of recombinant Escherichia coli from 10.35g DCW / L to 70g DCW / L, volume enzyme activity from 18205U / L to 103530U / L, and the fermentation level by 4.7 times.

The invention discloses a lactic acid production device for fermentation and separation coupling and a lactic acid fermentation process using expanded bed in-situ adsorption to realize online separation. In the invention, an expanded bed and a fermentation tank are coupled, the online separation of lactic acid fermentation is realized by using the expanded bed method, so that the feedback inhibition of lactic acid is relieved, the yield and the conversion rate of the lactic acid fermentation are increased, and meanwhile, the problem of bed blockage by thalli when a fixed bed is used for absorbing the lactic acid in the prior art. Untreated fermentation liquor is permitted to directly enter a chromatographic column. Because the synchronization of fermentation and separation is realized, the cost of downstream extraction and separation in the prior art is greatly reduced.

The invention discloses a method for producing glutathione by fermentation of recombinant Escherichia coli. The method comprises the following stages of: (1) carrying out batch culture or fed-batch culture to obtain a great deal of recombinant Escherichia coli cells expressing exogenous bifunctional glutathione synthetase, wherein the bifunctional glutathione synthetase is protein which simultaneously has activities of gamma-glutamyl cysteine synthetase and glutathione synthetase; (2) carrying out over-expression on the bifunctional glutathione synthetase obtained in the stage (1); and (3) adding L-glutamic acid, L-cysteine and glycine precursor amino acids to realize high-efficiency production of glutathione by fermentation. According to the invention, the recombinant Escherichia coli strain expressing the exogenous bifunctional glutathione synthetase is used for producing glutathione by fermentation, so that the method not only has high GSH (Glutathione) synthesizing capability, but also is free from GSH feedback inhibition, and has the advantages of rapid reaction, high glutathione yield and short production period.

The invention provides a method of producing tetrahydropyrimidine by fermenting recombinant corynebacterium glutamicum. The recombinant corynebacterium glutamicum is obtained by the steps of performing overexpression in corynebacterium glutamicum to relieve an aspartokinase gene lysC of feedback inhibition; then replacing a promoter of a dihydropyrimidine dicarboxylic acid synthetase in the recombinant bacteria to weaken the activity of the dihydropyrimidine dicarboxylic acid synthetase; and then transferring tetrahydropyrimidine synthetic path related gene ectABC into the recombinant bacteria to obtain the recombinant corynebacterium glutamicum. The recombinant corynebacterium glutamicum provided by the invention can use different cheap raw materials to produce tetrahydropyrimidine by fermentation under a low salt condition, and cheap corn slurry can be also used as a nutritional component which replaces expensive yeast powder, so that the cost of the raw materials is further lowered. Meanwhile, the recombinant corynebacterium glutamicum provided by the invention solves the problem of biosafety, simplifies the post-extraction process and has a good market application prospect.