Combination of 4-Hydroxybutyrate Carbon Precursors as Substrate for Simultaneous Production of P(3HB-co-4HB) and Yellow Pigment by Cupriavidus sp. USMAHM13

Abstract

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] copolymer is a type of polyhydroxyalkanoate (PHA) that has attracted intensive attention in the medical applications. A novel P(3HB-co-4HB)-producing bacteria strain Cupriavidus sp. USMAHM13 accumulates high levels of PHAs and a yellow pigment that has potential antibacterial property. This present study was conducted to evaluate the effect of various combination of 4-hydroxybutyrate (4HB) carbon precursors on the biosynthesis of P(3HB-co-4HB) and yellow pigment. Combination of 1,4-butanediol with 1,6-hexanediol shows an effective yield on cell dry weight of 1.8–10.8 g/L, PHA content of 28–47 wt% and pigment concentration of 0.05–0.18 g/L. Enhancement of P(3HB-co-4HB) and yellow pigment production were successfully achieved using 1,4-butanediol with 1,6-hexanediol at $$\hbox {C/N}=23$$ which resulted in an outstanding increased of PHA content and pigment concentration of 52 wt% and 0.25 g/L, respectively. Furthermore, the addition of fructose had successfully induced the yellow pigment production by 61%, without affecting the growth and PHA accumulation. This report was proved to show the capability of Cupriavidus sp. USMAHM13 to produce high yield of P(3HB-co-4HB) with various 4HB monomer compositions and yellow pigment from various of 4HB carbon precursors. As this was the first to report on the high yield of yellow pigment production by Cupriavidus sp. USMAHM13, the selection of 4HB carbon precursors’ combination can serve a significant experience and strategy to increase both pigment and P(3HB-co-4HB) production.