Optimization of fermentation for phb biopolymer using oil palm trunk SAP as medium component

The uses of petroleum-based plastics are harmful because it cannot be degraded and is not environmental friendly. To overcome these problems, researchers have introduced a naturally occurring biopolymer which is polyhydroxybutyrate (PHB) as a substitute to the existing synthetic plastics. Polyhydroxybutyrate is an intracellular product of bacteria fermentation at physiological stress condition. PHB is being studied because of its unique properties and because it is biodegradable. Production of bioplastic using PHB in large scale involved higher production costs compared to the production cost of existing petroleum-based plastics. Optimization of fermentation for PHB biopolymer was studied in shake flask by using Cupriavidus necator in oil palm trunk sap as the medium component. Three parameters were studied which were the fermentation temperature, agitation speed and percent volume of oil palm trunk sap. The optimum levels of parameters were determined by using mathematical model. Inocula were done in shake flask to cultivate the bacteria in growth medium solution. Fermentations were done in 500 mL shake flasks containing mineral salt, ultrapure water, inoculum and oil palm trunk sap. The flasks were incubated in incubator shaker for 24 hours at different levels of parameter values. The products were analysed for cell dry weight and PHB contents. Based on the experimental results obtained by using the Method of the Path of Steepest Ascent for the determination of the parameter values, the optimum condition of fermentation for PHB biopolymer was at temperature of 31.3°C, 123 rpm for agitation speed and 38.5 % for percent volume of oil palm trunk sap. The concentration of PHB obtained at the optimum condition was 0.825 g/L and the biomass content was 3.55 g/L