Biopolymer products

Now, most metal ion/organic molecule chemical reactions inside cells also come to equilibrium rapidly. The organic products, made irreversibly available by synthesis under feedback control, contain a broad set of possible binding sites for selected metal ions mainly in soluble proteins (enzymes) and in the pumps for uptake or rejection managed at the cell membrane, as well as in the factors, transcription factors, necessary for controlled production of those organic products under the direction of the coded system. These ion-selective binding sites are common to all cells so that while all cells are based on similar major organic reactions and similar but specific biopolymer products, they also have in common a set of... 

Stafford N (2007) Large-scale biopolymer production, http //www.rsc.org/chemistryworld/ News/2007/May/14050701.asp, Accessed Dec 12 2008... 

Polylactic acid and 3 GT (3 carbon glycol terephthalate) are two biopolymers that are already being successfully produced in pilot plants. Their manufacturers (Dow for PLA and DuPont/Genencor for 3GT) expect to reduce the production cost to USD 1 per kilo or even lower by 2003. These biopolymers will then become competitive with polyester and nylon chips. Dow and DuPont have both begun the constraction of large-scale biopolymer production plants. 

After biosynthesis of the polyester and separation of the bacterial biomass from the supernatant, the required recovery process (typically a solid-liquid extractiOTi procedure) can constitute another not negligible cost factor, especially in large-scale production. Here extraction solvents that can easily be recycled will be of interest [53]. In order not to leave the patterns of sustainability in biopolymer production, it will be indispensable to concentrate the development of new extraction processes on such recyclable solvents that are also of environmentally sound nature [54], Typical harmful chlorinated solvents like chloroform must be avoided. A PHB production process embedded in an ethanol production plant has the advantage to utilise the medium chain length alcohol fraction (fusel alcohols) from the distillery step, consisting mainly of iso-pentanol. The application of the fusel alcohols as extracting solvents unites two important points On the one hand, this liquid normally constitutes a surplus product that has little market value. When used as an extraction solvent the costs for alternative solvents are saved. Furthermore, this extraction solvent is less harmful to handle than the classical extraction solvent chloroform [27],... 

The numbers in Figure 19.1 refer to new molecular entities (NMEs). These figures represent a composite of both small molecule therapeutics, or NCEs (for new chemical entities), and large biopolymer products, or NBEs (for new biological entities) that entered the marketplace each year. Eactors responsible for the trends shovm in Eigures 19.2 and 19.3 will be discussed in greater detail as this chapter proceeds. 

Microbial systems have proven to be low-cost, environmentally safe methods for improved biopolymer production. Leuconostoc mesenteroid.es, Pseudomonas pseudomallei, and Bacillus spp., and biopolymers produced by microbes have received much attention due to their easy adaptability to tools of genetic engineering [15]. 

KEN 12] Kendall A., A lifecycle assessment of biopolymer production fi om material recovery faciUty residuals . Resources, Conservation and Recycling, vol. 61, p. 69,2012. 

The use of waste materials as feedstocks for PHA biosynthesis constitutes a viable strategy for cost-efficient biopolymer production and supports various agro-industrial branches to overcome existing waste disposal problems. The subsequent Table 7.2 provides a compilation of selected carbon-rich waste streams that are reported to be potential feedstocks for microbial PHA production. Such carbon substrates that are of importance for human nutrition, like pure starch or edible oils from olives, soya or palm trees, are not included in this compilation. 

In many regions of the world, the industrial realization of value-added conversion of low-cost agricultural feedstocks can provide a certain degree of geopolitical independence for the involved countries. This means that the importing of fossil reserves can be avoided by replacing fossil feedstocks with efficient implementation of renewable resources available in the respective countries. In addition, the creation of different qualified jobs in these regions in the field of biopolymer production from local resources can provide a socio-economic benefit. 

These halogenated solvents, especially chloroform, pose a high risk not only to the environment, but also to the personnel working with them. In order to avoid leaving the patterns of sustainability in biopolymer production, it will be indispensable to concentrate the development of new extraction processes on such recyclable solvents that are also of an environmentally benign nature, such as lactic acid esters [73]. 

It was shown how industrial waste like surplus whey, crude glycerol phase, lignocellu-loses, molasses and residues from the slaughtering and biodiesel industry can be upgraded to substrates for biopolymer production. Applying such waste streams as carbon source can be regarded as the most promising route to make the entire PHA biopolymer production process economically competitive this is valid for bulk plastics made of petrochemical competitors as well as for special polymers currently used for niche products. 

Beside the raw material supply and the fermentation process itself, downstream processing for polymer recovery from the surrounding cells is another cost-determining factor in biopolymer production. Especially for this process step, additional research progress is required in order to decrease the demands for energy and chemicals that severely antagonize the sustainability of PHA production. 

Figure 10.3 Global biopolymer production capacity distribution.

The integration of biopolymer production into an existing sugar cane mill has been realized on a pilot scale by the company PHBISA in Brazil, where the saccharose obtained is converted to bioethanol and partly to PHA. In this scenario, the energy required for bioethanol and biopolymer production is generated by burning surplus biomass, namely bagasse. The fusel oil fraction of the bioethanol distillation is applied as an extraction solvent for PHA isolation from microbial biomass (Nonato et al. 2001). 

Fig. 8 PHBISA, Brazil Integration of biofuel and biopolymer production in the sugar cane industry actual (solid arrows) and potential (dashed arrows) utilization of the waste streams. The scheme provides a mass balance of the annually produced amounts of commercialized sucrose, bioethanol and PHA starting from 2,160,000 tons sugar cane per milting season (values based on...

Salmiati Z, Ujang MR, SaUm MF, Md D, Ahmad MA (2007) IntraceUular biopolymer productions using mixed microbial cultures from fermented POME. Water Sci Technol 56 179-185 Schubert P, Steinbuchel A, Schlegel HG (1988) Cloning of the AlcaUgenes eutrophus poly-fL hydroxybutyrate synthetic pathway and synthesis of PHB in Escherichia coU J. Bacteriol. 170 5837-5647... 

Biopolymers, however, present numerous advantages (i) they are biodegradable, (ii) they are biocompatible (they can be used on the human body as prostheses, implants etc.), (iii) they can be produced by some effluents and industrial by-products, particularly from the food industry, (iv) biopolymer production takes into account environmental issues, (v) they have a wide range of applications and properties, (vi) production costs have been decreasing as a result of the current interest from the environmental area... 

SinhaJ.Tae Bae J, Pil Park J, Hyun Song C.WonYun J. Effect of substrate concentration on broth rheology and fungal morphology during exo-biopolymer production by Paecilomyces japonica in a batch bioreactor. Enzyme Microh Technol 2001 29 392-9. 

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