Study On Breeding Of γ-decalactone Producer, Optimization Of Fermentation Conditions And Its Cells Immobilization

γ-decalactone(GDL) is a lactone, used to formulate cream, peach, orange and coconut flavors. Its feasibility, inducement, fermentation condition and immobilized yeast cells were investigated by using Yarrowia lipolytica As2.1405 and castor oil as substrate.Yarrowia lipolytica As2.1405 was taken as the original fungus in this study, producing 143mg/L GDL. After UV and NTG mutagenesis, the GDL production of the mutant Y-1-6 reached to 318mg/L.Optimization of GDL production by the mutant Y-1-6 was carried out through single factor and orthogonal experiment. The optimum fermentation medium was: castor oil 60g/L, peptone 30g/L, yeast extract 25g/L, Na2HPO4·12H2O 1.2g/L, Tween-80 4g/L, KH2PO4 1.5g/L, pH6.5, temperature 25℃, inoculum's size 8%, volume in flask 50mL/500mL. After fermentation for 48 hours, the production of GDL reached to 402mg/L under abovementioned conditions.In order to lower the toxicity of outcome to cells and increase GDL production, Yarrowia lipolytica AS2.1405 was studied to immobilize. The immobilized yeast cells of better mechanical structure and mass transfer could be made by the mixture of PVA and carrageenin to ferment and produce GDL. The optimal conditions were decided through main indexes: bead intensity and GDL yield. The optimal composition of entrapping agents: 80g/L PVA, 5g/L carrageenin, microbial cells 0.1g/mL, immobilization time 24 hours. The product of GDL could reach to 482 mg/L. The output of GDL was 20 percent increase with immobilized yeast than before.