Isolation and characterization of triacylglycerol-accumulating microorganisms which can utilize wood polysaccharide

Abstract

Triacylglycerol is an ester which is made of glycerol and three fatty acids. This compound is an important feedstock for biodiesel production. In this study, several strains of oleaginous bacteria were isolated from environmental sample based on their ability to grow in mineral salts medium supplemented with wood-derived sugars such as cellulose, arabinose, xylose, mannose, and galactose. The lipid accumulating bacteria were selected based on fluorescent signal from hydrophobic inclusion in the cytoplasm after incubation in selective medium containing lipophilic dye 0.5 % (w/v) nile red. The lipid content was analyzed using thin layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS). In this study, three bacterial isolates 2HPCS1R4, 1LPCS2R2, and 1LPCS2R14 were selected among several candidates. TLC analysis of hydrophobic substance from 1LPCS2R2 and 1LPCS2R14 showed two overlapped discrete bands corresponded to triacylglycerol reference band. While 2HPCS1R4 displayed a faint band located above the reference band. GC-MS analysis confirmed that the bands consisted of fatty acid methyl esters with alkyl length varied from C12 to C17. Kinetic study showed that the fastest growing strain was 1LPCS2R2 had the highest growth rates and when grown in glucose (μ = 0.29 h-1) and xylose (μ = 0.16 h-1). In conclusion, this study has identified of prospective bacterial isolates for commercial biodiesel production.