Whole-Cell Catalyzed Generation of Alkyl Esters from Acid Oils

Abstract

The work carried out on the whole cell catalyzed transesterification of acid oil using selected fungi; the study demonstrates some salient features which hitherto have been either known to a limited extent or not reported till date. The study resulted characterization of five fungi exhibiting potential to grow and utilize acid oil as carbon source to the extent of upto 70% (v/v) supplementation in growth medium. One of the strains, Aspergillus flavus, was observed to catalyze transesterification of acid oils to alkyl esters, to the extent of ≥ 98% at 70% (v/v) acid oil supplementation. The optimized conditions required for maximum lipase activity of the said strain with acid oil have been identified. Stepwise addition of alcohol resulted in better conversion of acid oil to ethyl ester. In addition, the dried biomass could effectively enhanced the transesterification reaction in shorter duration. Scale-up production of biodiesel from acid oil using immobilized whole cells catalyst with the use of bioreactor reached upto 95.4% within 24 h reaction. The resultant alkyl ester was noted to meet the specifications of major international biodiesel standards to a significant extent. The present study is of importance in identifying the potential use of whole-cell fungi as biocatalyst for generation of alkyl esters including biodiesel from acid oil is useful for commercial applications.