Research On Interaction And Optimization Conditions Of ?-carotene Production Of Blakeslea Trispora

Natural carotenoids are widely used in health care,food processing and other fields with a broad market prospect because of their excellent antioxidant effect.At present,fermentation through the co-culture of Blakeslea trispora(+)and Blakeslea trispora(-)is an important approach to obtain natural carotenoids.Blakeslea trispora is famous for its fast growth and high output,but it has both sexual life history and asexual life history,which makes the interactions between Blakeslea trispora(+)and Blakeslea trispora(-)in the co-culture system become too complex and difficult to control,it leads to the ?-carotene production became low yield and instability.Therefore,we systematically characterized the morphology changes of Blakeslea trispora(+)and Blakeslea trispora(-)in the co-culture system.In addition,we studied the relationship between the sexual reproductions,trisporic acid and beta carotene in the fermentation through the co-culture of Blakeslea trispora(+)and Blakeslea trispora(-).Then we constructed an artificial neural network to optimize the fermentation process.The main results are as follows:(1)We discovered the key factor which can make Blakeslea trispora(+)and Blakeslea trispora(-)produce a large number of ?-carotene.By studying the different ways of fermentation through the co-culture of Blakeslea trispora(+)and Blakeslea trispora(-),we discovered that Blakeslea trispora(+)and Blakeslea trispora(-)produce only small amounts of ?-carotene when cultured alone but synthesized a large number of ?-carotene in co-culture,so we optimized the inoculation ratio according to this.Through the connected bottle experiment,we identified that the high yield of beta carotene is caused by both direct and indirect contact between Blakeslea trispora(+)and Blakeslea trispora(-),some substance is the key factor makes Blakeslea trispora(+)and Blakeslea trispora(-)produce a large number of ?-carotene.(2)Identified the key substance which can make Blakeslea trispora(+)and Blakeslea trispora(-)produce a large number of ?-carotene.Through the extraction and detection of the fermented liquid in different ways of vaccination,we identified trisporic acid as a distinctive product in the co-culture of Blakeslea trispora(+)and Blakeslea trispora(-).We found that the addition of trisporic acid analogues increased the production of ?-carotene,Blakeslea trispora(-)cultured alone have a 74.6 percent increase,co-culture of Blakeslea trispora(+)and Blakeslea trispora(-)have a 20.4 percent increase,Blakeslea trispora(+)cultured alone do not change significantly,that means trisporic acid play an important role in high production of ?-carotene.And the addition of exogenous ?-carotene improved the yield of ?-carotene in this co-culture system,the yield of ?-carotene has a 69.8 percent increase.This discovery suggested that there is a positive correlation between the metabolic flux of trisporic acid and ?-carotene,and they metabolize in an approximate positive feedback loop.(3)We established a reliable model of ?-carotene and optimized many factors with the introduction of the BP neural network.Then,we adopted a more efficient and accurate algorithm,particle swarm optimization(PSO),to solve the model,and figured out the most optimal fermentation condition: at the beginning of fermentation with 140 ?mol/L ionone;cold stimulation at 4? for 1.75 h at third,fifth,seventh days and with 50 ?mol/L jasmonic acid methyl ester,45 ?mol/L hydrogen peroxide in the third day of fermentation.In this fermentation condition,the yield of beta carotene came out as 212.2±6.3 mg/L,a 74 percent increase compared with the condition before optimization.