Poly(3-hydroxy butyrate) synthesis from a mutant strain Azotobacter vinelandii utilizing glucose in a batch reactor

Abstract

The synthesis of the biopolymer poly(3-hydroxy butyrate) P(3HB) was studied in a batch reactor using a mutant strain of Azotobacter vinelandii utilizing glucose. The objective of the present study was to optimize the cost of production by using glucose as substrate. In order to achieve this, a mutant strain was developed using a UV-mutagenic technique which is capable of utilizing glucose as substrate and giving a better yield. The effect of temperature, pH, glucose concentration and inoculum concentration on the production of P(3HB) using the optimized media was studied. The optimum temperature, pH, glucose concentration and inoculum concentration for growth and P(3HB) synthesis were found to be 30 °C, 7.5, 2.4% (w/v), and 0.63 g/l, respectively. The experiments were carried out to establish the kinetics of P(3HB) production by measuring cell mass, P(3HB) and glucose concentrations as a function of time in the batch reactor under optimum conditions. Growth kinetic models such as Monod, logistic and modified logistic models were used to predict the experimental data. The respective growth models incorporated in the Leudeking–Piret model and modified Leudeking–Piret models were used to predict P(3HB) formation rates and glucose consumption rates.