Optimization of media composition by using sugarcane molasses as substrate for production of polyhydroxyalkanote in ralstonia eutropha strain

Abstract

A study of polyhydroxyalkanoate (PHA) production was conducted using pretreatment of sugarcane molasses as main substrate to obtain low-cost medium for fermentation process. Ralstonia eutropha strain was used to produce polyhydroxyalkanoate in the nutrient limitation conditions. The study involved determination of significance interaction between different parameter which is sugarcane molasses, ammonium sulfate and urea using Central Composite Design in order to optimize the PHA concentration. Two-stage fermentation techniques were used to obtained high yield of PHA fermentation. First stage fermentation involved bacteria growth phase in a nutrient rich medium and second stage fermentation involved culturing bacteria strain in the limited nutrient medium. The fermentation process was incubated at fixed set point values of agitation speed, pH, fermentation period and temperature. The highest PHA composition recorded was 72.03 % at 2 % sugarcane molasses, 0.21 % ammonium sulfate and 1 % urea concentrations.