Comonomer composition distribution of P(3HB-co-3HP)s produced byAlcaligenes latus at several pH conditions

A series of poly(3-hydroxybutyric acid-co-3-hydroxypropionic acid) (P(3HB-co-3HP)) samples was biosynthesized by fermentation with Alcaligenes latus using sucrose/3-hydroxypropionic acid as carbon source at different pH conditions from 6.0 to 8.0. The copolymers were compositionally fractionated using the mixed solvent chloroform/heptane. It was found that A. latus produces P(3HB-co-3HP)s with different 3HP content under the same conditions except for the pH value of the medium. The higher the pH value of the fermentation medium is, the less 3HP units are introduced into the copolyester. The comonomer composition distribution for the copolyesters also depends on the pH value of medium. The copolyester sample produced at pH 6.0 has a much broader composition distribution than those produced at pH values between 6.5 and 8.0. The copolyester with the narrowest distribution was obtained at pH 7.0. It was also found that the distribution becomes broader with increasing fermentation time.