Screening Of 2-phenylethanol Yeast Producing And Its Immobilization Technology

2-Phenylethanol is an aromatic alcohol with a soft rose fragrance.It is naturally found in the leaves,flowers and fruits of plants.As a fragrance,it is widely used in the fields of food,cosmetics and washing products.Its derivatives are also the main components of the rose scent.With the improvement of social development and living standards,the people pay more attention to"natural"and"green"products.The chemically synthesized high-purity edible grade 2-phenylethyl alcohol is limited,and the plant extraction process is cumbersome and expensive,resulting in a shortage of 2-phenylethanol in the market.The use of mild and environmentally friendly microbial conversion to synthesize natural 2-phenylethanol has important research value and market prospects.In this paper,the optimum conditions for the synthesis of 2-phenylethanol from the high-yield 2-phenylethanol strains selected from cheese were studied.The research contents were as follows:(1)Screening of high-yield 2-phenylethanol yeastThe 2-phenylethanol tolerance and yield determination of yeast isolated and purified from Xinjiang traditional cheese were screened to obtain a yeast with the highest yield of2-phenylethanol tolerance,named 1 and capable of 4 g/L2-phenylene ethanol was grown on a solid plate,and the yield of 2-phenylethanol was 2.51 g/L.It was identified by molecular biological method as Pichia kudriavzevii 1.The ethanol yield was 18.86 mL/L,and the inhibition of yeast with 2-phenylethanol was not obvious.(2)Optimization of fermentation conditions for 2-phenylethanol production from yeastThe optimum conditions for the production of 2-phenylethanol by single factor test and response surface analysis were:glucose:70 g/L,yeast extract:1 g/L,L-phenylalanine 6.2 g/L,dihydrogen phosphate Potassium 4 g/L,magnesium sulfate 0.8 g/L,temperature 30°C,loading volume 50 mL/L and inoculum 1.2×10~7 cells/mL,under this condition,the amount of 2-phenylethanol converted to strain was 3.53 g/L,an increase of 40.64%over the original2.51 g/L.(3)Optimization of cell immobilization conditions for 2-phenylethanol yeastThe conditions of embedding yeast cells with sodium alginate as carrier were optimized by single factor experiment and orthogonal experiment.The optimal immobilization conditions were:sodium alginate 3%,calcium chloride 1.2 mol/L,yeast concentration 1.2×.10~8 cells/mL and immobilization time 2 h.Under this condition,the amount of the modified granules converted to 2-phenylethanol was 3.32 g/L.A 250 mL conical flask containing 50mL of the conversion solution was found in a cycle of fermentation for 24 h at a temperature of 150 r/min at 30°C.The amount of 2-phenylethanol in the first three batches of immobilized cells was above 3 g/L,and the batch 9 was able to synthesize 2-phenylethanol above 1.5 g/L,which was significantly better than the free cells.