Green Synthesis of the Flavor Esters with a Marine Candida parapsilosis Esterase Expressed in Saccharomyces cerevisiae.

The green synthesis of the flavor esters, n-propyl acetate, isobutyl acetate and isoamyl acetate had the advantages over the chemical synthesis. The esterase from Candida parapsilosis could transform n-propanol, isobutanol and isoamyl alcohol into n-propyl acetate, isobutyl acetate and isoamyl acetate, respectively. The esterase was expressed in Saccharomyces cerevisiae. At 30 °C for 1 d, the concentration of n-propyl acetate, isobutyl acetate and isoamyl acetate synthesized by the esterase expressed in Saccharomyces cerevisiae was 24.6 mg/100 mL, 8.3 mg/100 mL, 5.6 mg/100 mL, respectively. Expression of the esterase has a practical significance for flavor ester synthesis by green biochemical process.

Tandem integration of aerobic fungal cellulase production, lignocellulose substrate saccharification and anaerobic ethanol fermentation by a modified gas lift bioreactor.

Cellulase production, lignocellulose saccharification and bioethanol fermentation were integrated to efficiently produce bioethanol. A modified gas lift bioreactor was developed for bioethanol production by the integrated process. Cellulase production was achieved using Aspergillus niger mycelia immobilized within the reactor in wire meshes, and Saccharomyces cerevisiae cells were immobilized in resin beads. During four repeated batches fermentation, cellulase activities were more than 6.28 U/mL and bioethanol production was over 45.9 g/L for 48 h. The factual bioethanol conversion efficiency was 86.8%. By the modification of the modified gas lift bioreactor, immobilization of Aspergillus niger mycelia and Saccharomyces cerevisiae cells, aerobic cellulase production, substrate saccharification and anaerobic bioethanol fermentation were successfully integrated in tandem. The integrated processes is of great significance in bioethanol production.