Poly bacterial degradation

Low viscosity poly(a-olefins), e.g., 2 and 4 cSt, can be classified as relatively biodegradable in aqueous systems as defined by the CEC L-33-A-93 test however, this does not mean that all poly(a-olefins) are biodegradable. The concept of biodegrability is very difficult to define. The extremely low water solubility of poly(a-olefins) decreases the available surface area for bacterial degradation. If high biodegrabilities are required, linear polyol esters tend to be used. 

In the case of fibrinogen, the slow time course of adsorption onto poly(HEMA)/Silastic and Silastic make attempts at obtaining true equilibrium adsorption isotherms difficult because the fibrinogen solutions will undergo slow fiber formation unless protected from bacterial degradation. Also, storage of such solutions is a problem since fibrinogen... 

Fujimaka, T. el al (1994) Biodegradable polyesters. US Patent 5310782 (to Showa High Polymer). Fukunaga, F. et al (1976) Bacterial Degradation of Poly(vinyl alcohol). / />cch Kokai 76125786. 

Fukimaga, F. et al (1977) Bacterial Degradation of Poly( inyl. Alcohol)./n/>an Kokai 7794471. 

Table 1. Kinetic parameters of some bacterial poly(3HB) synthesizing and degrading enzymes (values in mmol 1 )... 

Extracellular Degradation of Polymers Related to Bacterial Poly(HA) 316... 

A hairpin structure in bacterial mRNAs with a p-independent terminator (Fig. 26-7) confers stability against degradation. Similar hairpin structures can make some parts of a primary transcript more stable, leading to nonuniform degradation of transcripts. In eukaryotic cells, both the 3 poly (A) tail and the 5 cap are important to the stability of many mRNAs. Life Cycle of an mRNA... 

Akiyama, M.,Tsuge,T., and Doi, Y. 2003. Environmental life cycle comparison of poly-hydroxyalkanoates produced from renewable carbon resources by bacterial fermentation. Polym. Degrad. Stab., 80,183-194. 

In the former case, a bacterial or fungal colony on the surface of the material releases an extracellular degrading enzyme which breaks down the polymer chains into smaller units (dimers and ohgomers), which then are absorbed through the microorganisms ceU membrane and metabolised as a source of nutrient (carbon). It has been proposed that this mechanism first hydrolyses the chains of the amorphous phase of poly-(3-hydroxybutyrate) (PHB) and then proceeds to attack the chains in the crystalline state. The enzymatic degradation rate decreases as the crystallinity increases [15, 16]. 

Higher molecular weight PHB and its copolymers with poly(3-hydroxy-valerate) (PHV) can be synthesized from racemic P-butyrolactone and P Valerolactone, using an oligomeric alumoxane catalyst. These polyesters, with only partial stereoregularity, are less susceptible to enzymatic degradation than the bacterial ones. Polyhydroxy-butyrate-valerate (PHBV) is produced by Monsanto as Biopol . 

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