Selection And Application Of Fatty Acid Hydratase

As one of the main renewable resources in nature,fatty acids have a wide range of sources and huge base,so they have great potential for industrial application.At present,most of the applications of fatty acids are based on their carboxyl terminal esterification properties.However,the research on the activation and application of its alkane chain is relatively less.For the C=C bond in the alkyl chain of unsaturated fatty acids,the main applications are thermally cleavage and epoxidation reaction.There are still many disadvantages in the current industrial application,and the application effect is also limited by the purity,efficiency,positioning and other factors,resulting in the low market value of products,and even part of the process is stopped in the laboratory stage and difficult to scale up.Therefore,directional and efficient derivatization of C=C bond,endowing fatty acid alkyl chain with new physical and chemical properties,and preparing a series of high value-added products based on this is the focus and difficulty in the field of oil chemical industry.Based on the above problems,this paper developed three unsaturated fatty acid application processes based on fatty acid hydratase.In the first part.Using the properties of the hydrase FA-HY2(from Lactobacillus acidophilus NTV001),which can catalyze linoleic acid to produce specific ?-hydroxy olefin structure,combined with the directed pyrolysis reaction of ?-hydroxy olefin structure,A new process of bio-chemical catalysis of linoleic acid for the preparation of biomaterials and biofuel feedstock was designed.In this part,the expression and hydration conditions of FA-HY2 recombinant protein in E.coli were optimized.Under the optimal hydration conditions,the yield of 10-hydroxy-12-octadecenoic acid(HOD)reached 85%.Then,the directional pyrolysis of 10-HOD was studied,The yields of ?-octene and 10-oxodecanoic acid were 35%and 39%,respectively.In this part,an efficient way to utilize carbon atoms in fatty acid molecules is proposed,which provides a new choice and reference for the processing and application of fatty acids.In the second part of the work,the hydrolase BbMCRA2(from Bifidobacterium breve NCIMB 702258)was used to catalyze different unsaturated fatty acids,and the process of preparing high purity linolenic acid by hydrolase kinetic separation was designed.The kinetic resolution of oleic acid,linoleic acid and linolenic acid by hydratase was realized by optimizing the catalytic conditions including temperature,enzyme dosage,pH and buffer dosage.The content of linolenic acid in the mixed fatty acid could be increased from 55%to 68%in a single reaction.After three reaction separation,the content of linolenic acid could be increased to 75%.It can effectively improve the content of linolenic acid in natural oil and provide a new solution for the purification of linolenic acid.In the third part,based on the efficient catalytic reaction of oleic acid by hydratase Em-OAH,a multi enzyme cascade catalytic reaction route for sebacic acid production from oleic acid was explored.The results showed that the combination of hydratase,alcohol dehydrogenase,Baeyer-Villiger monooxygenase and lipase could effectively transform oleic acid to sebacic acid.The limiting step in this process is the oxygenation efficiency of Baeyer-Villiger monooxygenase.This study provides a basic separation for the realization of the green and efficient multi enzyme biocatalysis system.