Process optimization and production of Polyhydroxyalkanoates from sugarcane molasses by Pseudomonas sp. PhNs10.

Abstract

Replacing synthetic plastics with eco-friendly alternatives like polyhydroxyalkanoates is a feasible option to reduce the level of plastic pollution. A non-virulent strain isolated from the soil of a local plastic waste disposal site was studied for the production of PHA in glucose as well as sugarcane molasses media. The 16S rRNA identification confirmed that the strain was related to the Pseudomonas genus. The carbohydrate utilization study revealed the ability of the strain to utilize different carbohydrates. The PHAs produced in both media were compared for their chemical and thermal properties using NMR, FTIR, Raman spectroscopy, contact angle measurement, and DSC. The production process in both media was optimized using RSM and the optimized conditions for glucose medium were found to be glucose and yeast extract concentrations of 3.33% and 0.33% respectively, pH of 7.11, and incubation time of 70 h. While the optimized conditions for molasses medium were found to be molasses concentration of 6.18%, pH 7.24, Inoculum percentage of 4.05%, and incubation time of 85 h. The growth, substrate utilization, and production kinetics study of Pseudomonas sp. PhNs10 revealed a specific growth rate of 0.07 and 0.04/h, specific biomass productivity of 0.06 and 0.04 g/L.h, and specific PHA productivity was 0.04 and 0.01g/L.h for glucose and molasses medium respectively. The yields of PHA from biomass were found to be 0.62 and 0.55 g of PHA per g of biomass for glucose and molasses medium respectively. The yield of PHA from glucose and molasses medium were found to be comparable and these findings could aid in the economic production of PHA