DefinePK

Abstract

Catalysis of used cooking oil (UCO) transesterification by whole-cell lipase produced by solid state fermentation (SSF) of agro-industrial wastes makes overall biodiesel synthesis greener, economic and sustainable. In the present study, Aspergillus niger KY401431was isolated from butter and identified based on 18S rRNA gene homology. Optimization of several biodiesel synthesis process stages including SSF conditions for A. nigerKY401431 whole cell lipase production and UCO transesterification reaction conditions was carried out. Optimum SSF conditions, based on A. niger KY401431 biodiesel synthesis ability from UCO, were: a combined substrate of wheat bran (WB) and sesame meal (10/0.3, w/w), initial moisture content of 90%, initial pH of 8, inoculums size of 5x 107 spores/g substrate and incubation at 30oC for 6 days. Whereas, the best conditions for UCO transesterification were: 10% (w/w of UCO) biocatalyst, 3:1 methanol/UCO molar ratio with three-step additions at 0, 24 and 48h, 20% water (w/w of UCO), 30°C reaction temperature and reaction time of72 h. Under optimized process conditions, UCO conversion to fatty acid methyl esters (FAME) was improved by about 5-folds, producing a final biodiesel yield of 75.5%.