Amino acids, production from biomass

Major biotechnological uses of the biomass carbohydrate moiety have attracted worldwide attention. Controlled cellulose degradation by cellulases may produce materials for important multifarious applications carbohydrates that can be used in the food and beverage industries, cellulose microfibril fragments for non-caloric food additives, hyperabsorbent cellulose fibers from fragmented cellulose microfibrils which can be used in biomedical, commercial and house-hold absorbent materials. Biomass-derived glucose syrups can also be used as carbon source in industrial fermentations for the production of antibiotics, industrial enzymes, amino-acids, and bulk chemicals. 

It is evident that natural proteins are not a primary source of large amounts of amino acids, despite the fact that many of the acids are commercially significant chemicals and a few are commodity chemicals. The technical difficulties just alluded to include undesirable distributions of the amino acids in natural proteins, the sensitivity of proteins and amino acids to chemical hydrolysis conditions, racemization, the multiplicity of the product acids and the often low concentration of the desired acid or acids in the hydrolysate, and the consequent separation problems. Microbial synthesis of specific amino acids from biomass substrates or biomass-derived intermediates often has substantial advantages over thermochemical processing methods and is used for the commercial production of several of the amino acids. This is discussed in more detail in the next section. 

The heteroaromatic ring system in chlorophyll is a prominent tetrapyrrole and is of particular interest since related products are often preserved in sediments as porphyrins. As shown in Figure 25, its immediate precursor is aminolevulinic acid (C5) which is in turn synthesized from glycine and succinyl-CoA with loss of CO2 (C2 + C4 -> C5 + Ci) or from glutamate (C5). The carbon flowing to tetrapyrroles is thus closely related to that in amino acids and in intermediates from the TCA cycle and is expected to have an isotopic composition close to that of biomass. In specific analyses of chlorophyllides (i.e. the non-... 

A large number of products In the pharmaceutical and food Industry Is obtained from fermentation processes. Examples are amino acids, stereoregular organic acids, antibiotics, ethanol, etc. In a classical fermentation process the product formation Is strictly coupled to cell growth resulting In a possibly unfavorable byproduction of biomass. Furthermore these processes are typically performed as batch operations. 

---