Preparation of gutta-percha through fermentative degradation of Eucommia ulmoides Oliver leaves by recombinant yeast expressing cellulases from Trichoderma reesei

Efficient extraction of gutta-percha from Eucommia ulmoides is important to enable its large-scale utilization in the industry. Enzymatic action of organisms offers a mild, effective and cheap technology for extracting natural products by destroying the outer wall of cells, and releasing the intracellular metabolites. In this study, Saccharomyces cerevisiae was engineered to express the recombinant cellulase genes, Cel5A/Cel6A, from Trichoderma reesei, which was then used to extract gutta-percha from the leaves of E. ulmoides. The leaves were pretreated with NaOH, ultrasound and cellulase. The results showed that when the leaves of E. ulmoides were pretreated with ultrasound (20 kHz, 30 min), with a fermentation temperature of 30 & DEG;C at pH 7, the extraction rate of gutta-percha was the highest (2.35 %). Further determination of the molecular characteristics and the thermal stability of gutta-percha using the thermogravimetric analyzer and size-exclusion chromatography revealed no significant difference in thermogravimetrics between the treatment groups. After analyzing the DCS (Differential scanning calorimetry) and TG (Thermogravimetry) curves, it was found that the gutta-percha was of & alpha;-crystal type and had a good thermal stability at 300 & DEG;C. It had the highest average molecular weight of 29.283 x 104 in the NaOH pretreatment group. This study provides a new strategy for the extraction of gutta-percha from E. ulmoides Oliver leaves.

Automated summary

Efficient extraction of gutta-percha from Eucommia ulmoides leaves using enzymatic treatment with cellulase was achieved. The pretreated leaves showed the highest extraction rate (2.35%) and good thermal stability, with gutta-percha exhibiting an α-crystal type structure.