Biopolymers, degradation and

Figure 8.10 Humic substance formation depicted by the early biopolymer degradation and abiotic condensation models. (Modified from Hedges, 1988.)...

Hasirci V, Lewandrowski K, Grosser JD et al (2001) Versatility of biodegradable biopolymers degradability and an in vivo application. J Biotechnol 86 135-150... 

Degradable polymers have been advocated as an alternative to conventional oil-based plastics, and their production has increased considerably in recent decades. Before concluding our discussion of solutions to the problem of plastics waste and pollution, a brief consideration of the applications and limitations of these novel materials is worthwhile. Biopolymers - degradable and biodegradable polymers with comparable functionality to conventional plastics - can now be produced on an industrial scale however, they are more... 

S8 Paknikar, KM., Nagpal, V., Pethkar, A.V. and Rajwade, J.M. (2005) Degradation of lindane from aqueous solutions using iron sulfide nanoparticles stabilized by biopolymers. Science and Technology of Advanced Materials, 6, 370-374. 

Another major component of the cell membranes are the lipopolysaccharides, which are present as phospholipid bilayers. Following the death of bacteria, the biopolymers that constitute their cell walls and membranes become part of the detrital organic carbon pool. The great abundance of these biopolymers in seawater and the sediments is a reflection of their resistance to chemical degradation and the important role that bacterioplankton play in marine biomass production. 

There are also structural differences between humic substances or UDOM collected from rivers and oceans (Table I). Humic substances and UDOM from rivers are enriched in aromatic components compared with their counterparts from the ocean. Terrestrial vegetation is relatively rich in aromatic components, such as lignins and tannins, and this is reflected in the greater aromatic nature of DOM in rivers. These biopolymers are relatively resistant to microbial degradation and are important components of river DOM. Humic substances and UDOM from the ocean are enriched in carbohydrates compared with their counterparts from rivers. This is consistent with observations of higher C-normalized yields of neutral sugars in bulk DOM from the ocean compared with rivers (Table I). 

The 48 kDa protein was purified for Al-terminal sequencing and shown to have significant homology with porin-P from the gram negative bacterium Pseudomonas aeruginosa. Tanoue s data are the most direct evidence to date that resistant biopolymers selectively survive degradation and accumulate as oceanic DOM. 

Many different compounds can be used as biopolymer additives, most of them are quite similar to those used in traditional polymer formulations. The use of various compounds as plasticizers, lubricants, and antioxidants has been recently reported.Antioxidants are normally used to avoid, or at least minimize, oxidation reactions, which normally lead to degradation and general loss of desirable properties. Phenol derivatives are mostly used in polymers, but vitamin E and a-tocophe-rols are those most commonly found in biopolymer formulation. 

Wellington, S.L., 1980. Biopolymer solution viscosity stabiUzation—polymer degradation and antioxidant use. SPEJ (December), 901-912. 

The sugar and phenol analyses showed that there were chemical degradation and losses. In the alder and oak, respectively, 90 and 98% of the polysaccharides and 15 and 25% of the lignin was lost or degraded. Approximately 75% of the degraded biopolymers had been lost from the two samples. 

Initially, P. putida strains were evaluated as degrader for aromatic xenobi-otics in bioremediation processes [38, 128, 129], as plant-growth promoting microorganism [130], as well as biocontrol agent [131]. Today, P putida is regarded as an efficient producer for biotechnological production of a broad portfolio of biopolymers, chemicals, and pharmaceuticals [11]. However, most... 

Chitin, the precursor of chitosan, is a nitrogen containing polysaccharide and is second most abundant biopolymer after cellulose. It is widely distributed in the shells of crustaceans such as crabs, shrimps, lobsters, prawns, squilla, etc., as well as in the exoskeleton of marine zoo-plankton, including coral, jellyfish, and squid pens. About 20-40% chitin is present the exoskeleton of these animals. It is also present in smaller quantities in insects such as butter flies ladybugs, and the cell walls of yeast, mushrooms, and other fungi [Fig. 19.4]. However, since the crustacean shells [crabs, shrimps, lobsters, etc.] are waste products of food industry, these are commercially employed for the production of chitin and chitosan [1, 4, 18], It is believed that at least 10 gigaton of chitin is synthesized and degraded and it is also estimated that over 150,000 tons of chitin is available for commercial use annually. 

---