Biodiesel Production from Brassica juncea Using Oleaginous Yeast

The present study explores the potential of Brassica juncea as a low-cost substrate for biodiesel production through the growth of oleaginous yeast. Firstly, the selected lignocellulosic biomass, i.e., Brassica juncea, was thermochemically pretreated using dilute sodium hydroxide. Optimization of thermochemical pretreatment resulted in significant removal of lignin and hemicellulose with 8.4% increase in cellulose content. Further, the sugar hydrolysate of pretreated biomass was used as a substrate for the growth of selected oleaginous yeast (Cryptococcus sp. MTCC 5455). Lipid and biomass production was optimized using central composite design (CCD) based on response surface methodology (RSM). Maximum biomass and lipid content of 32.50 g/L and 11.05 g/L, respectively, was obtained at 30 °C temperature, pH 6.0, and after 5 days of incubation. The oleaginous yeast lipid was further transesterified using immobilized lipase. The highest fatty acid methyl ester 15% FAME yield was obtained after 10 h of enzymatic reaction. Next, the results of specific gravity, viscosity, flash points, and cloud point of obtained biodiesels were conformed to the ASTM D975 standard. Overall, the present study put forth the cost-effective approach for lignocellulosic biomass-based oleaginous lipid production toward the green synthesis of biodiesel.