Steering of β oxidation intermediates to polyhydroxyalkanoate copolymer biosynthesis by fatty acids and inhibitors using Taguchi design

Polyhydroxyalkanoate (PHA), a biological macromolecule, is a polyester of fatty acids, synthesized in many bacteria. In the present study, Bacillus endophyticus was used to produce PHA copolymer, different fatty acids are incorporated to the medium as a co-substrate (sucrose is primary substrate) to induce PHA pathway, and β oxidation inhibitors are added to generate intermediates. To estimate the impact and significance of seven factors (fatty acid types, fatty acid concentration, time of fatty acid addition, inhibitor types, inhibitor concentration, time of inhibitor addition and sucrose concentration) on the PHA production in shake flask, statistical experimental design of Taguchi orthogonal array was adopted. L16 orthogonal array with seven factors out of which five factors in two levels and two factors in four levels was considered with an experimental matrix of 16 trials. It was observed that there was increase in the PHA copolymer accumulation by 56.5%. Among seven factors, fatty acid types exhibited the highest contribution of 52.11% for copolymer production (PHA), while time for the addition showed 0% contribution. Optimal conditions provided by the model were validated for the production of PHA. Quality of the polymer was confirmed by FTIR analysis.