Glutamic acid fermentation

In the 1950s, a group of coryneform bacteria which accumulate a large amount of L-glutamic acid in the culture medium were isolated (21). The use of mutant derivatives of these bacteria offered a new fermentation process for the production of many other kinds of amino acids (22). The amino acids which are produced by this method are mostiy of the T.-form, and the desired amino acid is singly accumulated. Therefore, it is very easy to isolate it from the culture broth. Rapid development of fermentative production and en2ymatic production have contributed to the lower costs of many protein amino acids and to their availabiUty in many fields as economical raw materials. 

Microorganisms requite several minerals such as ferrous and potassium ions which play important roles in glutamic acid fermentation. Other important culture conditions include regulating aeration stirring. The biosynthesis of L-glutamic acid is performed under regulated aerobic conditions. 

Progress in fermentation technology has made it possible to raise the accumulation and the yield of L-glutamic acid above 100 g/L and 60% based on the total amount of sugar. AppHcation of genetic engineering techniques for further improvement is also in progress. 

An industrial fermentor of capacity up to several hundred kiloliters equipped with aeration and stirring devices, as well as other automatic control systems, is used. The cultures must be sterilized and aseptic air must be used owing to the high sensitivity to bacterial contamination of L-glutamic acid fermentation. 

MSG is the sodium salt of the amino acid glutamic acid. It is made commercially by the fermentation of molasses, but exists in many products made from fermented proteins, such as soy sauce and hydrolyzed vegetable protein. 

Classical examples of industrial biotechnology include the manufacture of ethanol, lactic acid, citric acid, and glutamic acid. The share of renewables in the feedstock of the chemical industry is expected to increase substantially in the years to come [2-4], A newcomer here is propane-1,3-diol (DuPont/Tate Lyle), with the start-up of industrial fermentation foreseen within one year. 

The complicated technology used makes this approach economically uncompetitive with fermentation processes for the production of natmally occurring amino acid, such as L-phenylalaitine, L-glutamic acid or L-lysine, for which large markets exist, and for which significant economies of scale in production costs can thus be gained. 

A new method for the preparation of soy sauce has been developed. The new scaled-up method divides the moromi process into two processes autolysis and fermentation. Because of the utilization of high temperatures, the new process permits the production of a NaCl free autolyzate from koji. Division of the fermentation process into two separated processes permit better control of lactic acid fermentation and alcohol fermentation processed which used to require great skill. The new scale-up procedure for soy sauce production yields a product in half the time required by the traditional (conventional) method and still produces a soy sauce with high levels of the desirable Bavor component, glutamic acid. Utilization of this protocol by the soy sauce producing industry should have significant economic impact to bo producers and consumers. 

The measurement of pH is also used to control NH3 feeding in glutamic acid fermentation [2]. 

When an NHg solution is used as a nitrogen source of fermentation, the consumption of NHg decreases the pH of the culture broth. A pH stat control utilizes the pH change as a process variable where the NHg addition is manipulated so as to keep the pH value constant during fermentation. The pH stat is often employed in a fed-batch cultivation of industrial glutamic acid production (high NHg consuming fermentation) using molasses as a feedstock. 

Nakamura, T., Kuratani, T., and Morita, Y. (1985) Fuzzy control application to glutamic acid fermentation. Proceedings of IFAC Modelling and Control of Biotechnology Processes, pp. 211215. 

L-Glutamic acid 105 NONESSENTIAL AMINO ACIDS Fermentation (WS) Synthesis from acrylonitrile and resolution MSG. taste enhancer... 

The impact of glutamic acid bacteria on monosodnim glutamate cost was dramatic. In 1950, MSG was obtained from natural products (i.e., soybean) and cost 4/kg. When the first fermentation process started up in 1961, the pnee dropped to 2/kg. By 1970 the price settled to about l/kg. and in 1983 approximately 220,000 tons of MSG/year were being produced by fermentation, worldwide, with a sales value of about 550 x 106. 

Deamination 17 Examples of deamination and decarboxylation include conversion of amino acids to fusel oil (leucine to isoamyl alcohol, isoleucine to amyl alcohol, and phenylalanine to phenyl ethanol). Fusel oil formation is a normal function of all yeast fermentations (in alcoholic beverages, levels range from trace to 2200 parts per million). Deamination Glutamic acid to gamma-OH-butyric acid (S. cerevisiae). 

The microbial sensor for acetic acid was applied to a fermentation broth of glutamic acid. The concentration of acetic acid was determined by the microbial sensor and by a gas chromatographic method. Good agreement was obtained the regression coefficient was 1.04 for 26 experiments. 

Glutamic Acid Sensor. A rapid automatic measurement of glutamic acid in fermentation media is required in fermentation industries. 

The concentrations of glutamic acid in some fermentation broths were determined by the microbial sensor and by the Auto-analyzer method. The results were in good agreement. The response of the sensor was constant for more than 3 weeks and 1500 assays. Thus the microbial sensor appears to be very attractive for the determination of glutamic acid. 

Chen and Su [102] L-Glutamate L-Glutamic acid fermentation L-Glutamate oxidase/ onto a cellulose triacetate membrane Oxygen electrode ... 

The procedure towards an environmentally benign process starts with the selection of raw materials in addition to conventional raw materials from the petrochemical industry based on low- to medium-boiling aliphatic and aromatic hydrocarbons, replenishable raw materials from nature are increasingly available nowadays. In the simplest cases, these can be carbon sources, such as glucose and sucrose for fermentation, but also more complex molecules, frequently obtained from the chiral pool or through inexpensive fermentation from carbon sources, such as glutamic acid or citric acid. Table 20.2 lists a selection of raw materials from the chiral pool, with their estimated costs per kilogram. 

---