Bacterial biopolyesters

Extensive studies in the molecular biology and physiology of the bacterial biopolyester synthesis has been made in the last decade. Previous research activities were mainly aimed at the biotechnological production of the extracted and semicrystalline thermoplastic polyester materials. Recently, however, it has been recognized that the intracellular polyester inclusions or those derived from in vitro synthesis can be considered as natural bionanoparticles. 

Sequence distribution and chemical structure of mass-selected macromolecules of macroinitiators derived from selected biopolyesters were accomplished recently with the aid of ESI-Mtechnique. The NMR and ESI-MS evaluation of the chemical structure of macroinitiators obtained by partial depolymerization of natural PHB, PHBV and PHO revealed that due to the elimination reaction they contain olefinic and carboxylic end groups. Based on the ESI-MS" studies of PHBV macroinitiator obtained by partial alkaline depolymerization of natural PHBV (containing 5 mole % of hydroxyvalerate units) the microstructure of this bacterial copolyester was assessed, starting from dimer up to the oligomer containing 22 repeat units. ... 

The free radical crosslinking of bacterial polyesters obtained from SOYO has also been reported [36]. Thus, poly(-3-hydroxy octanoate) containing unsaturated side chains (PHA-SOYO) were produced from SOYO in the presence of Pseudomonas oleovorans. Subsequently, PHA-SOYO adducts wctc crossUnked, thermally or under UV irradiation, in the presence of a free radical initiator and ethylene glycol dimethacrylate as the crosslinker. The network yield reached 93 per cent and the Tg of the biopolyester increased from 60°C to 40°C aftCT crosslinking. 

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