24 Introduction to Renewable Biomaterials
1.3.9.5 Nutrition
Another commercially important biotechnological product based on sugar is l-lysine.
It is one of the essential amino acids not synthesized by humans and animals but by
plants. Therefore, humans and animals depend on l-lysine-containing food and feed.
However, as the amino acid profile of plant biomass does not meet the demand of
livestock like poultry and hogs, it is beneficial to add the limiting amino acids. However,
livestock animals eat as long as the demand of the most limiting feed amino acid is
satisfied and overflow amino acids are excreted. As amino acids contain nitrogen, con-
sequently there is a significant burden of nitrogen-loaded manure. By adding l-lysine
feed transformation efficiency into animal biomass improves and nitrogen excretion
is significantly reduced. Mostly the bacteriumC. glutamicumis cultivated in amino
acid fermentation, which uses sugar as carbon source. Production strains are especially
optimized to focus the metabolism on l-lysine synthesis and excretion. Another amino
acid produced by fermentation from sugar is l-glutamic acid, commercialized as a food
condiment especially in Asia. Global production volume is in the range of 1.2 million
tons (l-glutamic acid), 0.5 million tons (l-lysine), and only a few hundred tons of special
amino acids for medical applications such as l-histidine. The market price parallels
the production volume, thus demonstrating the strong impact ofeconomy of scaleon
production cost. Whereas l-glutamic acid, the largest by volume, is commercialized at a
price of about $1 kg−^1 , l-histidine is marketed at about $90 kg−^1 (Lothar Eggeling, 2006).
1.3.9.6 Polymers
Biopolymers reached a share of 1.6 million tons (0.7% of total polymer market) but
are expected to grow to more than 6 million tons in 2017 (European Bioplastics, 2014;
Statista, 2013). There are two groups of bioplastics: (i) bio-based or partially bio-based
nonbiodegradable plastics such as bio-based polyethylene (PE) and polyethylentereph-
thalate (PET) and (ii) bio-based and biodegradable plastics such as polylactide (PLA)
(Table 1.26).
As bio-PE and bio-PET are identical to their fossil-based counterparts, it is easy to use
it in established processes without any modification. Therefore, such compounds are
calleddrop-inchemicals. Though on the one hand a perfectdrssop-inPE demonstrates
Table 1.26Global bioplastics capacities by material
type (1000 tons per year; 2013) (European
Bioplastics, 2014).
Nonbiodegradable bioplastics
Bio-PA PTT Bio-PEE Bio-PET30
80 110 200 600
Biodegradable bioplastics
PLA
Starch
blends Polyesters PHA
Cellulose
(regenerated)
185 183 175 34 27
PA, polyamide; PTT, polytrimethylene terephthalate;
PEE, polyethylethylene; PHA, polyhydroxyalkanoate.
