Extraction of Eucommia ulmoides gum and microbial lipid from Eucommia ulmoides Oliver leaves by dilute acid hydrolysis.

Abstract

Eucommia ulmoides gum (EUG) is an important natural biomass rubber material, which is usually extracted from Eucommia ulmoides Oliver (EUO). In the extraction process of EUG, pretreatment is the most important step which can efficiently damage EUG-containing cell wall and improve yield of EUG. The FT-IR, XRD, DSC and TG results showed that the thermal properties and structure of the EUG from the dilute acids hydrolysis residue are similar with that of the EUG directly extracted from EUO leaves (EUGD). EUO leaves hydrolysis with AA had the highest EUG yield (16.1%), which was higher than the EUGD yield (9.5%). In the case of the EUO leaves hydrolysis with 0.33 ~ 0.67 wt% of acetic acid (AA), the total sugar was stable in the range of 26.82-27.67g/L. Furthermore, the EUO leaves acid hydrolysate (AA as reagent) was used as carbon sources for lipid-producing fermentation by Rhodosporidium toruloides. After 120h of fermentation, the biomass, lipid content and lipid yield were 12.13g/L, 30.16% and 3.64g/L, respectively. The fermentation results indicated organic acids were no toxic for Rhodosporidium toruloides and the AA also could be used as carbon source for fermentation.