Fermentation industry lysine

The fermentation wastes Corynebacterium glutamicum biomass) were obtained in a dried powder form from a lysine fermentation industry (BASF-Korea, Kunsan, Korea). The protonated biomass was prepared by treating the raw biomass with a 1 N HNO3 solution for 24 h, thereby replacing the natural mix of ionic species with protons. The resulting C glutamicum biomass was dried and stored in a desiccator and used as a biosorbent for the sorption experiments. 

Cadaverine (diaminopentane, DAP), a carbon-5 aliphatic metabolite, is a minor member of the biogenic polyamine family. It owes its trivial name to its first discovery in 1885 during systematic investigation of the putrefaction process of human cadavers [52]. In contrast to DAB, there is no efficient petrochemical production route available, which for a long time hampered its industrial application in the polymer industry. However, several bio-based production processes have meanwhile been developed for DAP production from renewable resources [6, 12, 15-17, 53]. Only recently, Cathay introduced the fully biobased polyamide PA5.10 Terryl , which entered the market in 2015. While the proprietary production process relies on biocatalytic conversion of the rather high-priced fine-chemical lysine, other attempts aim at a fully novo biosynthesis with streamlined cell factories for the direct fermentative production of DAP from cheap conventional fermentation feedstock. For establishing a one-step fermentation process for DAP, the industrial lysine producers E. coli and C. glutamicum were therefore the ideal metabolic chassis. 

The Corynebacterium glutamicum mutant generally is used industrially in direct fermentation of lysine. Molasses is the most common carbon source. Sufficient amounts (over 30 micrograms/liter) of biotin must be included in the medium to prevent the excretion of glutamic acid. This biotin requirement usually is met by using molasses as the carbon source. The fermentation runs at temperature about 28 to 33°C, and pH 6 to 8. High aeration is desirable. The final product concentration is around 60g/liter, and the fermentation cycle is 48 to 72 hours. The yield of lysine on carbohydrate is about 40 percent. The formation of lysine from molasses can be represented as follows ... 

Fermentation is also the basis for the manufacture of biomass foodstuffs (primarily protein for animal and human consumption), amino acids (especially monosodium glutamate and L-lysine), and the major industrial feedstock and gasoline additive, ethanol. 

The major producers of this amino acid are presently Chinese companies. The usual production process is the extraction of the dimer form cystine from keratin hydrolysates, mainly human hair, and the electrochemical reduction to cysteine. As the raw material human hair is not well accepted by the end consumer, especially not by vegetarian people, there is a big demand for alternative production processes. One company succeeded in a synthetic route to produce cysteine, but this route is quite expensive. In addition to that synthetic starting materials are not really the favorites in the food industry. Attempts to establish a fermentation process as common for other amino acids, like glutamate or lysine, have failed so far. 

Adsorbing lysine on ion exchange resin is probably the most vddely used industrial method of purifying lysine. The fermented broth is adjusted to pH 2.0 with hydrochloric acid and then passed through a column of strong acid cation resin in the NH/ form. Dilute aqueous ammonia may be used to elute the lysine from the resin. 

Amino acids, citric acid, lactic acid, propanediol, penicillin G, synthetic drug intermediates, and therapeutic proteins are among the industrially relevant products of fermentation and cell culture that have been targets for metabolic engineering. Some ofthis work has been adopted by industry (see [72], section 16.4.1). The major aim was to optimize the yields of industrial products, which was efficiently realized with Corynebacterium glutamicum for lysine and tryptophan, and at the Dupont company for 1,3-propane diol production [107-109]. 

L-glutamic acid. Today 1.5 Mio mto a of this amino acid are produced worldwide and predominantly used in food as a flavour-enhancing additive. The essential amino acids L-lysine, L-threonine and L-tryptophan are produced by fermentation for the feed additive market. In 2004 worldwide 770,000 mtoa L-lysin and 65,000 mto a L-threonine were produced by bacterial fermentation. According to Ajinomoto sales of feed additive amino acids grow up to 9% per year. Today Evonik Industries produces feed grade L-lysine, L-threonine and L-tryptophan by large-scale fermentation and produces pharma-grade L-alanine, L-aspartic acid, L-isoleucine, L-proline, L-valine and L-tryptophan for applications in the pharma markets. More products from fermentation are shown in Table 12.2. 

Corynebacterium actively excretes amino acids through its cell wall membrane and does not degrade L-lysine due to the lack of lysine-decarboxylase. For 60 years all these characteristics have made this microbe the species of choice in L-lysine production. In addition it demonstrates the potential of natural biosynthesis pathways for commercial purposes. In contrast Escherichia coli entered the field of industrial amino acid fermentation not because of comparable advantages provided by nature but because of the availability of effective tools for genetic engineering. In the early 1980s such methods were state of the art for Escherichia coli but were only on an infant level for Corynebacterium. Developing industrial strains based on Escherichia coli, which at that time was not broadly covered by intellectual property (IP), provided room to build new IP in the field of amino acid fermentation. 

Wheat bran, starch, powdered skim milk, casein, peat, com flour, and the like are reported to be good fillers for drying liquid bioproducts in fodder, fermentation, pharmaceutical, and similar industries [18,19]. As applied to drying of lysine, for example, the use of wheat bran as an active filler gives the following advantages ... 

For better control of fermentation and to reduce production costs, complex media components are avoided and mostly refined carbon sources are used for the industrial production of L-lysine. Sucrose can be obtained from cane or beet molasses, and glucose is provided in hydrolysates of corn, cassava, or wheat starch [30, 83]. Ammonia, as nitrogen source, can be added pure or as salts [32]. Further media components are vitamins, in particular biotin, as well as salts and trace elements. Amino acids for auxotrophic production strains can be provided by peptones, corn steep liquors, or soybean meal hydrolysates [30]. Preferably, media are sterilized continuously, whereas carbon sources and nitrogen sources are typically sterilized separately to avoid Maillard-type reactions [32]. Sterility is important for processes with the mesophilic and neutrophilic C. glutamicum with bacilli as main contamination risk [84], while phage infection is hardly a problem. 

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