Fractionation and characterization of microbial polyesters containing 3-hydroxybutyrate and 4-hydroxybutyrate repeat units

A detailed investigation of 3HB/4HB product microstructure and heterogeneity was conducted. A. eutrophus was used to form a 3HB/4HB-containing product using 4-hydroxybutyric acid as the sole carbon source. The product formed was found to consist of three components: (1) P3HB, (2) P (3HB-co-82 mol % 4HB), and (3) P(3HB-co-28 mol% 4HB). This result is in contrast to previous work with the same bacterium and culture conditions which claimed that a simple random P(3HB-co-4HB) was obtained. These observations suggest that microbial polyesters may have complex structures that require careful fractionation and subsequent analysis.