Polyhydroxybutyrate commercial production

Some natural polyesters, such as polyhydroxybutyrate, are commercial products of micro-organisms. Outside of the cell the enzymatic synthesis of high-molecular-weight polyesters may be impractical on any sensible scale, but the synthesis of smaller blocks with a molecular weight of several thousand is practical. The ester bond is formed under conditions where water activity is low, and the concentrations of alcohol and carboxylic acids are high. The reaction (Scheme 6.28), which is a transesterification between... 

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