Glutamic Acid Fermentation Research Articles

Time-dependent kinetic models for glutamic acid fermentation

A group of time-dependent kinetic models for glutamic acid fermentation are presented. These can divide cell growth into three stages: the positive acceleration stage, negative acceleration stage, and equilibrium stage. The substrate consumption is also divided into three stages: the negative acceleration state, positive acceleration stage, and exhaustion stage. Product formation is also separated into three stages: the lag stage, positive acceleration stage, and negative acceleration stage. By comparing data from the laboratory and factory, good agreement between experimental values and predicted values is found and in comparisons to reported models in the documents about glutamic acid fermentation, the present models are most satisfactory.

Fermentation and recovery of glutamic acid from palm waste hydrolysate by Ion‐exchange resin column

Glutamic acid produced from palm waste hydrolysate by fermentation with Brevibacterium lactofermentum ATCC 13869 is produced with a remarkably high yield compared with that produced from pure glucose as a carbon source. The produce yield is 70 g/L with glucose, wherease, when palm waste hydrolysate is the fermentation medium in the same bioreactor under same conditions, it is 88 g/L. The higher yield may be attributed to the fact that this organism has the ability to convert sugars other than only glucose present in the hydrolysate. Bioreactor conditions most conducive for maximum production are pH 7.5, temperature of 30 degrees rmentation period of 48 h, inoculum size 6%, substrate concentration of 10 g per 100 mL, yeast extract 0.5 g per 100 mL as a suitable N source, and biotin at a concentration of 10 pg/L. Palm waste hydrolysate used in this study was prepared by enzymic saccharification of treated palm press fiber under conditions that yielded a maximum of 30 g/L total reducing sugars. Glutamic acid from fermentation broth was recovered by using a chromatographic column (5cm x 60 cm) packed with a strong ion-exchange resin. The filtered broth containing glutamic acid and other inorganic ions was fed to the fully charged column. The broth was continuously recycled at a flow rate of 50 mL/min (retention time of 55 min) until glutamic acid was fully adsorbed on the column leaving other ions in the effluent. Recovery was done by eluting with urea and sodium hydroxide for total displacement of glutamic acid from the resin. The eluent containing 88 g/L of glutamic acid was concentrated by evaporation to obtain solid crystals of the product. (c) 1995 John Wiley & Sons, Inc.

Simulation of the effect of mixing, scale-up and pH-value regulation during glutamic acid fermentation

A mixing model is coupled with fermentation kinetics in order to simulate a fermentation as a function of mixing conditions and scale-up. The mixing model for a batch stirred tank with three stirrers consists of three regions, each of them characterized by an ideally mixed compartment around the stirrer and two macromixers, i.e. cascades of tank-in-series, describing the recirculation flow. The model contains four parameters — radial and axial circulation time, volume of the ideally mixed stirrer compartment and the number of tanks in each cascade. These values, determined by Mayr et al. in function of the operational conditions and scale-up, were choosen to simulate the fermentation of glutamic acid to show the pH-fluctuation at different control and scale conditions. By choosing optimal regulation properties, such as input flow rate and/or concentration of the base, regulation span, position of the pH-electrode and base input location, etc., fluctuations of the pH-value in the bio-reactor can be minimized. However, the negative effect of insufficient mixing conditions can be reduced only by an increasing number of the base input places. In large scale fermentors, the axial circulation time is rather high, about 5–10 times larger than the radial one. This might result in a large amplitude of the pH-fluctuation. As it is shown, using an input place for base in each stirrer region, the negative impact of the insufficient axial mixing on the fermentation can be diminished perfectly. In this case ammonia should be fed into the reactor as an aqueous solution.

Effect of different carbon sources on growth and glutamic acid fermentation by Brevibacterium sp.

AbstractExperiments were carried out to find the efficiency of Brevibacterium sp. to utilize different carbon sources (glucose, fructose, sucrose, maltose, lactose, xylose and starch) for its growth and for the production of glutamic acid. Except starch, all the carbon sources supported the growth of the culture, which showed a preferential choice of growth and activity when grown on glucose as sole carbon source. Mixed substrate fermentation did not improve the yield of amino acid. Maximum glutamic acid yields (6.86 mg/ml) were obtained when 2% glucose medium was fermented under optimized conditions for 48 h.

Simulation of the effect of mixing, scale-up and pH-value regulation during glutamic acid fermentation

Simulation of the effect of mixing, scale-up and pH-value regulation during glutamic acid fermentation

Fuzzy supervisory control of glutamic acid production

In glutamic acid fermentation, the molasses feeding policy and time of penicillin addition significantly affected glutamic acid production, and a fuzzy supervisory control system was developed for their quasi-optimal regulation.From the trend of the experimental data, production rules and membership functions of fuzzy inference were devised to determine the quasi-optimum molasses feeding policy and penicillin addition time. A computer with multitasking operating system was used for the construction of the control system with fuzzy inferencing, which decided the control policy every minute, and the feed rate was controlled automatically. The pattern of residual sugar concentration was almost the same as that of maximum glutamic acid production under manual operation. Using the computer control system, stable production was maintained at the highest level of 71 to 75 g/L.

Membrane fluidity in glutamic acid-producing bacteria Brevibacterium sp. ATCC 13869

The bacterial secretion of glutamate was studied through plasma membrane fluidity, measured by anisotropy using the fluorophore TMA-DPH incorporated in the lipid part of the cell membrane. Cells of Brevibacterium sp. ATCC 13869 (wild type) were switched from the biotin-limited, producing state to the biotin-supplemented, non-producing state, and back. The following conclusions could be drawn: 1. It was not possible to detect any change in anisotropy by switching the cells from biotin-limited biotin-supplemented, as well as from biotin-supplemented, to biotin-limited, media. 2. The anisotropy value in the glutamic acid fermentation remains constant during the lag, exponential, growth, production and stationary phases. 3. The treatment of cells with a neutral synthetic polyester of ethylene-and propyleneoxide with soya oil-fatty acids increased the anisotropy values, indicating incorporation of the surfactant. 4. Glutamate secretion is not coupled with membrane fluidity, so a leak providing a general fluidization of the membrane could not be detected.

13C nuclear magnetic resonance studies of glucose metabolism in L-glutamic acid and L-lysine fermentation by Corynebacterium glutamicum.

Glucose metabolism in Corynebacterium glutamicum was investigated using 13C nuclear magnetic resonance (13C NMR) spectroscopy. L-Glutamic acid and L-lysine producers were cultivated in medium containing [1-13C]- or [6-13C] glucose, and the 13C NMR spectrum of the culture filtrate was measured. In each fermentation, the ratio of the contributions of the Embden-Meyerhof pathway (EMP) and the hexosemonophosphate pathway (HMP) (EMP/HMP) was calculated on the basis of the 13C population at each carbon in the products. The EMP/HMP was estimated as 80/20 in glutamic acid fermentation; in contrast, it was 30-40/60-70 in lysine fermentation. These results indicate that HMP contributes much more in lysine fermentation, probably because of the greater requirement of NADPH in lysine formation from glucose.

Amino acid-dependent transport of sugars by Fusobacterium nucleatum ATCC 10953.

Resting cells of Fusobacterium nucleatum 10953 (grown previously in a medium containing glucose) failed to accumulate glucose under aerobic or anaerobic conditions. However, the addition of glutamic acid, lysine, or histidine to anaerobic suspensions of cells caused the immediate and rapid accumulation of glucose. Except for the amino acid-dependent transport of galactose and fructose (the latter being transported at approximately one-third the rate of glucose), no other sugars tested were accumulated by the resting cells. Amino acid-dependent uptake of sugar(s) by F. nucleatum was abolished by exposure of cells to air, and under aerobic conditions the rates of fermentation of glutamic acid and lysine were less than 15% of the rates determined anaerobically. The energy necessary for active transport of the sugars (acetyl phosphate and ATP) is derived from the anaerobic fermentation of glutamic acid, lysine, or histidine. Competition studies revealed that glucose and galactose were mutual and exclusive inhibitors of transport, and it is suggested that the two sugars (Km = 14 microM) are translocated via a common carrier. The products of amino acid-dependent sugar transport were recovered from resting cells as ethanol-precipitable, high-molecular-weight polymers. Polymer formation by F. nucleatum, during growth in medium containing glucose or galactose, was confirmed by electron microscopy.

Fuzzy Control Application to Glutamic Acid Fermentation

Consumption rate of ammonia in glutamic acid fermentation was found to be correlated with consumption rate of sugar. This gives a good control strategy for sugar feed rate to keep sugar concentration in a suitable range in fed-batch culture of glutamic acid fermentation.Slight changes of culture conditions, however, make some troubles in this control scheme. Fuzzy theory application could be found to be effective in such cases.

In vivo 15N NMR studies of regulation of nitrogen assimilation and amino acid production by Brevibacterium lactofermentum.

Glutamic acid producer Brevibacterium lactofermentum intact cells were used to demonstrate the feasibility of in vivo 15N NMR to follow nitrogen assimilation and amino acid production throughout the growth cycle. The induction of glutamic acid production by different growth conditions was studied. Intracellular and extracellular levels of free metabolites were estimated as function of oxygen supply and biotin concentration. 15N NMR enabled us to distinguish two phases during the fermentation. At the early stage of fermentation, glutamic acid was accumulated intracellularly independent of oxygen supply and no product was excreted. In the late growth phase, the permeability of the cells developed and L-glutamic acid was excreted. The effect of aeration and biotin concentration on cellular contents and excretion was also studied by 15N NMR. Glutamate, N-acetylglutamine, and glutamine were the main nitrogenous pools independent of cell culture conditions. Free ammonia was not accumulated intracellularly although glutamic acid fermentation can be characterized as the process of nitrogen assimilation and the uptake of ammonia is the key step. In conclusion, the application of in vivo 15N NMR spectroscopy unraveled various problems of nitrogen metabolism, in a rapid and nondestructive manner.

On-line estimation of cell growth for glutamic acid fermentation system

For glutamic acid fermentation system using molasses, on-line estimation of cell growth during the exponential growth phase was investigated based on the measurement of carbon dioxide evolution rate (CER). The CER was continuously calculated using microcomputer together with O2 and CO2 analyzers. It was found that a linear relationship existed between CER and cell concentration. Therefore it was possible to determine specific growth rate and specific CER accurately by measuring CER with time.

Immobilization of Brevibacterium flavum cells on collagen for the production of glutamic acid in a recycle reactor

AbstractIn this study, live cells of Brevibacterium flavum were immobilized for the production of glutamic acid. The reason for such a choice was that glutamic acid fermentation is an extensively studied fermentation and one which requires the viability of entire cellular faculties for the acid production. Brevibacterium flavum was chosen because it is an industrially used bacterium, and is very potent via a vis glutamic acid production. Studies were performed to find aeration and agitation conditions for optimal growth and glutamic acid productivity. Experiments were also done to find the optimum harvesting time. The cell activity peaks during the run of fermentation, and the time at which the peak occurs, was found. Conventional methods for immobilizing the cells on collagen were found to be lacking. The pH and drying were the two main reasons for loss of viability of the cells; the latter being more important. A modified immobilization procedure has been devised, which can immobilize live cells at any given pH and ionic strength, in contrast to the conventional method which requires the pH to be above 11 or below 3. This new method involves dialysis of collagen in suitable dialysis bags against water at pH7 (or buffer at any desired pH). The dialysed collagen blended at 20,000 rpm, resulted in a very smooth dispersion, unnoticeably different from collagen dispersion prepared at pH 11. The dispersed collagen was then cast and dried at an elevated temperature, and high air flow rate over the cast membrane, decreasing the time of drying from 6–8 hr ( in the conventional method) to 1.5–2 hr. The membrane has been tested for glutamic acid producing capabilities in a column reactor with the membrane spirally wound. The reactor has been operated under continuous conditions for 5–10 days with stable activities.

Amperometric determination of acetic acid with immobilized Trichosporon brassicae

A microbial sensor consisting of immobilized Trichosporon brassicae, a gas-permeable Teflon membrane and an oxygen electrode is suitable for the continuous determination of acetic acid in fermentation broths. When an acetic acid solution is pumped through the flow system, the current decreases to a steady state with a response time of 8 min; shorter pumping times give peaks which can also be measured. The relationship between the current decrease and the acetic acid concentration is linear up to 54 mg l -1, with a relative standard deviation of about 6% at the higher concentrations. Selectivity is satisfactory. Results obtained with this sensor and by gas chromatography for a glutamic acid fermentation broth were in good agreement (regression coefficient 1.04). The sensor was stable for more than 3 weeks and 1500 assays.

The Mechanism of the Formation of γ-Glutamylpeptides duringl-Glutamic Acid Fermentation Contributed Solely by γ-Glutamyltranspeptidase

The enzyme of Corynebacterium glutamicum that catalyzes the formation of various γ-L(D)-glutamylpeptides by the reversal of hydrolysis was found to be γ-glutamyltranspeptidase. The enzyme catalyzed γ-l(d)-glutamyl transfer reaction from various γ-L(D)-glutamyl- peptides including glutathione. The susceptibility of D-isomers was 17% of that of l-isomers. Many kinds of α-l-amino acids and peptides such as γ-l-GIu-l-GIu could be γ-glutamyl acceptors. These findings offered full explanation on the formation of γ-l-glutamylpeptides in the l-glutamic acid fermentation. In the supposed mechanism, γ-l-GIu-l-GIu is formed mainly by the reversal of hydrolysis from l-glutamic acid being richly produced by the bacteria. The other four minor peptides are formed by the γ-glutamyltranspeptidatkm from γ-l-GIu-l-Glu to some α-l-amino acids and to γ-l-GIu-l-GIu itself in the broths. The enzyme was found to be widely distributed among bacteria, especially in some strains of Corynebacterium, Bacillus, Erwinea, Serratia, Pseu...

The Isolation and Identification of γ-Glutamylpeptides froml-Glutamic Acid Fermentation Broths and Their Actions to the Crystallization of the Amino Acid

The Isolation and Identification of γ-Glutamylpeptides from<scp>l</scp>-Glutamic Acid Fermentation Broths and Their Actions to the Crystallization of the Amino Acid

Transient Accumulation of Fatty Alcohols by n-Paraffin-grown Microorganism

In the course of the study on glutamic acid fermentation by Arthrobacter paraffineus, in which n-paraffin was used as the sole source of carbon, it was observed that fatty alcohollike lipid was accumulated in the paraffin layer of culture medium. This was isolated and identified as the primary fatty alcohol having the corresponding carbon skeleton to that of n-paraffin used as the carbon source. The accumulation of fatty alcohol occurred rapidly in the early-log phase. The maximum amount of the accumulation was approximately 0.5 mg/ml after 6 hr incubation. In contrast with the production of glutamic acid and trehalose, the addition of penicillin gave no effect on the accumulation of fattv alcohol. Acetone-treated cells of the n-paraffin-grown bacterium still had the oxidative activity of n-paraffin, and the formation of fatty alcohol from n-paraffin was observed only by the reaction in alkaline pH.

The effect of sodium on the fermentation of glutamic acid by [formula omitted

The anaerobe Peptococcus aerogenes degrades glutamic acid to carbon dioxide, acetic and butyric acids and ammonia (Whiteley 1957). Horler, Westlake and McConnell (1966a) have shown using specifically labelled glutamic acid-14C that carbon five is converted to carbon dioxide and that butyric acid can be formed from the first four carbons of glutamic acid without passing through two carbon units. Washed cells of P. aerogenes , when suspended in a potassium phosphate buffer system at pH 7, readily fermented sodium glutamate; when glutamate was added as the free acid such preparations metabolized only about 10% of the added substrate. The addition of sodium ions, e.g. sodium sulphate, resulted in rapid and complete utilization of the glutamic acid. This paper describes the affect of sodium ions on the metabolism of glutamic and other amino acids by P. aerogenes .

Studies on Oxygen Transfer in Submerged Fermentations

In conventional shaken culture system, control of oxygen supply is performed by changing liquid volume in flasks and it necessarily introduces variation in the effectiveness of agitation and in the partial pressure of carbon dioxide. In jar or tank culture system, also, the changes in mechanical agitation and in the flow rate of air for control of aeration induce similar problems. It is impossible, therefore, to isolate the effects of oxygen on microbial metabolism from these accompanying ones. Hence, there is a basic requirement of making clear distinction among them, and in this paper the effects of agitation and carbon dioxide on product formation are presented in glutamic acid fermentation using the apparatus of controlling the level of dissolved oxygen throughout the fermentation.To obtain fundamental knowledge required for attaining adequate aeration, the rate of oxygen demand in glutamic acid fermentation was discussed in connection with its fermentation rates. On the basis of specific rates, rates...

Glutaconic acid, a product of the fermentation of glutamic acid by Peptococcus aerogenes.

Radioactive glutaconic acid was isolated from reaction mixtures in which Peptococcus aerogenes fermented glutamic acid-2-14C. The infrared spectrum, X-ray diffraction pattern, and melting point of the biologicai product is identical with that of chemically synthesized glutaconic acid. Cells of P. aerogenes fermented glutaconic acid, although at low rate, producing acetic and butyric acid. A possible role for glutaconic acid in the fermentation of glutamic acid is presented.