Isolation and optimization for polyhydroxyalkanoate production by novel bacterium cupriavidus sp. CB15

Abstract

The newly thermotolerant polyhydroxyalkanoate (PHA) producing bacterium, Cupriavidus sp. strain CB15, was isolated from corncob compost. The ability to synthesize PHA was confirmed by detection of PHA synthase (phaC) gene in the genome. This strain could produce PHA at 0.95 g/L (PHA content 75.3 wt%) using glycerol as a carbon source. To enhance PHA production, optimization based on one-factor-at-a-time (OFAT) experiments and response surface methodology (RSM) were conducted. The optimum conditions for growth and PHA biosynthesis were 10 g/L glycerol, 0.78 g/L NH4Cl, shaking speed at 175 rpm, cultivation temperature at 45 °C, and cultivation time at 72 h. Under these conditions, PHA production were increased to 2.09 g/L (PHA content of 74.4 wt%), which is 2.12-fold compared with non-optimized conditions. From Nuclear magnetic resonance (NMR) analysis, the extracted PHA was short-chain length PHA, poly(3-hydyoxybutyrate) P(3HB). The results of this study present that the newly thermotolerant bacteria Cupriavidus sp. strain CB15 is a candidate for PHA production under high temperatures by utilizing Petro-waste (glycerol).