Studies on Micromolecular Metabolism and Fermentation of Lycopene Produced by Blakeslea Trispora

Author:Liu Yang

Supervisor:yao jian ming


Degree Year:2019





Lycopene is one kind of terpenoid derivatives widely existed in nature.As a functional pigment,it is widely used in food and health products to provide people with anti-cancer and anti-aging effects.Lycopene from natural sources faces problems such as limited plant sources,unstable productivity and low purity.The lycopene synthesized by the chemical method is cheap and easy to obtain,but it contains many by-products,especially the impurities formed in the process of synthesis cause to the unknown risk on the safety of downstream application.Thus,the synthesized product are difficult to meet the requirements of the food and medicine fields.With the maturity of biological fermentation industry,the production of lycopene by fermentation has become the first choice in industry.At present,Blakeslea trispora is the only strain of lycopene in many choices to achieve the industrial production of lycopene.In this paper,CBOM2014378(+)and CBOM2014379(-)were used as the starting strain to screen out the blocker with industrial prospect,and a high yield mutant selection strategy of lycopene fermentation by Blakeslea trispora was established,according to the selected blocker.A kind of fermentation process based on the low risk blocker was established,and the fermentation process was optimized on the basis of high-yield strain,and the pilot-scale test was earied out.The main findings are as follows:1.Selection of blockersBased on the current domestic and foreign food safety regulations,targeted screening allows for substances with residue limits in the food industry,in order to better control the application of risk.Three effective blockers are selected,namely nicotine,imidazole and pyridine,which are characterized by the high blocking efficiency of nicotine and the highest purity of lycopene.Imidazole has been used in industrial production,with a lower cost,and its solid form is easy to operate;pyridine has the worst blocking effect,but it is the cheapest,and it is the only substance listed in domestic food safety regulations.2.Effects of different blockers on micromolecular metabolism of Blakeslea trisporaBy analyzing the micromolecular metabolites in the fermentation process based on different blockers,it was found that the safety risk of using nicotine was relatively low,which was easy to be removed in the post-treatment process,and the harmful derivatives were not metabolized in the fungi.Imidazole metabolized benzene ring derivative in the cells,and pyridine produced N heterocyclic derivative in the cells,and the inhibition efficiency of imidazole and pyridine on lycopene cyclase were much lower than that of nicotine.3.Screening of lycopene-producing strainsThe high-yield strains BT-LYC2017802(+)and BT-LYC2017403(-)were obtained by N+mutation and compound mutagenesis of Pingyangmycin and lithium chloride,using ethephon and nicotine as the sieving agents.The highest fermentation level of lycopene was about 2.33g/L,which was 44.2%higher than that of the original strain.4.Small-scale test of lycopene-producing strain in 50L fermenterThe fermentation process based on the high-yield fungus was established at the level of 50L fermenter.The basic medium,feeding strategy and adding method of nicotine were re-established,and the control model of dissolved oxygen was established.Finally,the highest lycopene yield of 2.02 g/L was obtained,which was 67%higher than the initial fermentation process of 1.21 g/L,and the yield of lycopene was increased by 67%compared with the initial fermentation process of 1.21 g/L.Through ventilation control,energy consumption is saved by I0%.5.Pilot-scale verification of lycopene-producing strain in 1000L fermenterThe lycopene yield of 1.83g/L was obtained by fermentation with dissolved oxygen as the main control parameter based on the 1000L scale-up process.The technological process basically verified the validity of the model for the control of dissolved oxygen.