Enzymatic biodiesel synthesis from Trichosporon shinodae yeast through circular economy: A greener approach

In the present study, crude glycerol, a by-product of biodiesel production, was supplemented to Trichosporon shinodae for higher lipid synthesis and further extracted (lipid) using ultrasonic-assisted extraction (UAE). Optimization of enzymatic transesterification (ET) using Response Surface Methodology (RSM) coupled with Central Composite Design (CCD) quadratic model of single-cell oil resulted in 90.03%(v/v) of maximum FAME's yield with methanol to oil ratio of 14.98, solvent to oil ratio of 0.270 in 12.52 h at 25.99 ? with 1.26%(v/v) initial water content. The developed model was significant, with an R-2 value of 95.20% and an adj.R-2 value of 91.97%. The developed RSM model was further utilized for optimization through the Modified Chaotic Invasive Weed Optimization (MC-IWO). The optimization results showed a maximum FAME's yield of 90.03% utilizing the MC-IWO parameters of 5 seeds with a 6% initial standard deviation using an exponent value of 2 with a population size of 15 in 56 generations. FAME's characterization of T. shinodae has revealed 58.8% (v/v) of saturated FAME's and 41.2% (v/v) of FAME's predominantly with oleic acid methyl ester content (38%,v/v). Fuel properties of T. shinodae showed kinematic viscosity of 3.9-4.4 mm(2)/s, iodine value (113-115 g I-2/100 g), cetane index (46-48), saponification value (203-206 mg/KOH), acid value (1.2-1.4 mg KOH/g) and higher heating value (39-40 MJ/kg). Blending experiments of T. shinodae biodiesel with conventional petroleum showed calorific values of B5, B20 and B100 were 48.63 MJ/kg, 43.45 MJ/kg and 38.35 MJ/kg, respectively. This study showed the potential of T. shinodae biodiesel, which can be used either as an additive or as a blend of conventional fuels.

Automated summary

This study investigates the potential of using crude glycerol, a by-product of biodiesel production, to enhance lipid synthesis in Trichosporon shinodae. The results show that enzymatic transesterification coupled with ultrasonic-assisted extraction can achieve a high yield of fatty acid methyl esters (FAME) from single-cell oil. The study also characterizes the fuel properties of T. shinodae biodiesel and explores its potential as a blend with conventional fuels.