Polyester Synthesis by Microorganisms

The chemistry of poly 0 -hydroxybutyrate) (PHB) involving structure, biosynthesis, and degradation has attracted the attention of scientists in connection with the environmental problems. In 1985, Holmes et aL at lO published that a 

Since Klibanov [21] demonstrated the first example rf enzymatic esterification and transesterification in organic solvoits, many enzymatic reactions in anhydrous media have been reported. It is now well known that some hydrolytic enzymes are stable even in organic solvents and can be used for certain types of condensation reactions that are difficult or impossible to achieve in aqueous media [22-28]. Most of these reactions concern lipase-caUdyzed esterifications and transesterifications [29]. 

An enzymatic oligomerization versus lactonization of various hydroxyesters has been reported [31]. When unsubstituted p, S, and e-hydroxyadd methyl esters 3 are subjected to the action of Porcine pancreatic lipase in anhydrous 

Lipase-catalyzed polymerization between an achiral dk rboxylic add and a primary glycol in an aqueousorgank mixture was reported [32J. A polycondensation of achiral 10-hydroxydecanoic acid catalyzed by lipase in benzene has also been claimed, however no convincing evidence was presented [33]. 

Enzymatic polycondensation ttf a dicarboxylic add and a died has been reported using lipase from Candida cyUndracea, Pseudomonas and Porcine pancreas [34]. Competitk n between linear polye r and macrocydic lactone formation was observed depei ing on the reactitm temperature. 

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