Enhanced microbial biodiesel production from lignocellulosic hydrolysates using yeast isolates

An effort in contributing to the reduction of fossil resource dependence along with utilization of lignocellulosic wastes, will be a beneficial approach in biofuel production. These approaches will aid in sustainable waste management and will contribute to economic feasibility. This study probed the exploitation of abundant, non-edible lignocellulosic wastes such as sugarcane bagasse and rice husk as a low-cost carbon source for the cultivation of oleaginous yeast isolates and lipid accumulation, respectively. The hydrolysis of the lignocellulose was explored by steam explosion alone to reduce the inflation of toxic compounds like hydroxy methyl furfural (HMF), furfural, and acetic acid. This optimization study investigated the effects of carbon sources (sugarcane bagasse hydrolysate, rice husk hydrolysate, and commercial glucose), nitrogen sources, and pH on biodiesel production using central composite design (CCD), and achieved a full factorial design. All the three variables were found to have a positive influence on biodiesel production. Greater biomass production was achieved by SY2 (Pichia kudriavzevii) with a value of −8.37 ± 0.067 g/L when sugarcane bagasse hydrolysate was used. Maximum lipid content of 37.99 ± 0.003% was attained by the strain G5 (Meyerozyma guilliermondii) upon using sugarcane bagasse hydrolysate in the production medium and higher lipid accumulation of 2.39 ± 0.003 g/L was attained by SY2 (Pichia kudriavzevii) upon using rice husk hydrolysate. Analysis of the kinematic properties of FAME (Fatty Acid Methyl Esters) was obtained using Biodiesel analyzer V1.1. software, and affirmed the values similar to the biodiesel standard values (EN 14214, ASTM, IS 15607). The kinematic studies used to figure out the quality of the biodiesel, revealed that FAME produced by SY2 (Pichia kudriavzevii) strain showed greater oxidation stability (37.17 h) and better kinematic viscosity (1.3084). These properties ensured that SY2 (Pichia kudriavzevii) strain was appropriate in producing exceptional quality biodiesel. Hence, the present investigation tried to prove the competency of the yeast isolates in sustainable biodiesel production by engaging agronomic wastes.