Enhanced production of biodiesel by Rhodosporidium toruloides using waste office paper hydrolysate as feedstock: Optimization and characterization

Environmental issues caused by fossil fuel and its rapid depletion demand the need to produce biofuel from renewable energy resources. The disposal of waste paper in landfills causes air pollution and contaminates groundwater. Hence, exploiting paper waste as a renewable resource for microbial lipid production can solve these environmental issues in a greener way. Further, these microbial lipids are a reliable source for biodiesel production. In this study, waste office paper was utilized as a substrate to produce microbial lipids through fermentation by the oleaginous yeast, Rhodosporidium toruloides, using a biorefinery approach. The production conditions were optimized using the Box-Behnken design; a fermentation time of 116.16 h, a C/N ratio of 60, and an inoculum concentration of 9.67% yielded a biomass of 10.55 g/L and a lipid yield of 6.13 g/L with a total lipid content of 58%. The major lipids produced were oleic acid (42%), palmitic acid (36%), stearic acid (9.8%), and myristic acid (8%), which clearly indicates the suitability of the lipids produced by R. toruloides for biodiesel production. The predicted biodiesel properties of the transesterified product met the international standard specifications. Hence, utilizing waste office paper for biodiesel production will be an effective way of mitigating the environmental pollution caused by waste paper and the harvesting of fossil fuels.