Isolation and Characterization of a Methylotroph Producing 3-hydroxybutyrate-3-hydroxyvalerate Copolymer

A bacterial strain C-02 using methanol as a carbon source was isolated from Gumi Industrial Estate and selected based on its rapid growth and capability of poly-$\beta$-hydroxybutyrate accumulation. Characteristics of strain C-02 showed that it belongs to the Methylococcaceae family, Type II subgroup. Strain C-02 could incorporate valerate into the PHB chain to form 3-hydroxybutyrate and 3-hydroxyvalerate (P(3HB-co-3HV)). Among various nutrient limitation tests, the nitrogen limitation test resulted in the highest content of P(3HB-co-3HV) per dry cell weight, 50$%$. Under the nitrogen limited condition, the average molecular weight of P(3HB-co-3HV) obtained was determined to be approximately $2.8\times 10^5$ daltons.